Heterozygous Variants Research Articles

Telomere-to-telomere assembly by preserving contained reads.

Automated telomere-to-telomere (T2T) de novo assembly of diploid and polyploid genomes remains a formidable task. A string graph is a commonly used assembly graph representation in the assembly algorithms. The string graph formulation employs graph simplification heuristics, which drastically reduce the count of vertices and edges. One of these heuristics involves removing the reads contained in longer reads. In practice, this heuristic occasionally introduces gaps in the assembly by removing all reads that cover one or more genome intervals. The factors contributing to such gaps remain poorly understood. In this work, we mathematically derived the frequency of observing a gap near a germline and a somatic heterozygous variant locus. Our analysis shows that (1) an assembly gap due to contained read deletion is an order of magnitude more frequent in Oxford Nanopore Technologies (ONT) reads than Pacific Biosciences high-fidelity (PacBio HiFi) reads due to differences in their read-length distributions, and (2) this frequency decreases with an increase in the sequencing depth. Drawing cues from these observations, we addressed the weakness of the string graph formulation by developing the repeat-aware fragmenting tool (RAFT) assembly algorithm. RAFT addresses the issue of contained reads by fragmenting reads and producing a more uniform read-length distribution. The algorithm retains spanned repeats in the reads during the fragmentation. We empirically demonstrate that RAFT significantly reduces the number of gaps using simulated data sets. Using real ONT and PacBio HiFi data sets of the HG002 human genome, we achieved a twofold increase in the contig NG50 and the number of haplotype-resolved T2T contigs compared to hifiasm.

Targeted long-read sequencing identifies missing pathogenic variant in unsolved 11β-hydroxylase deficiency

Background11β-hydroxylase deficiency (11β-OHD), caused by homozygosity or compound heterozygosity CYP11B1 variants, is the second most common cause of congenital adrenal hyperplasia (CAH). Due to the high degree of sequence identity between CYP11B1 and CYP11B2, chimeric genes, and complex structural variants (SVs), the conventional approach to gene testing for 11β-OHD is facing challenges. The study aimed to clarify the underlying genetic causes of two siblings of a Chinese family with 11β-OHD.MethodsPeripheral blood samples and clinical information were collected from subjects and their family members. Sex steroid concentrations were measured using LC-MS/MS. Long-range PCR-based next-generation sequencing (NGS), PCR assay and target long-read sequencing were used to detect the pathogenic variants.ResultsEarly onset hypertension, increased serum levels of adrenocorticotropin (ACTH), progesterone, testosterone, and decreased cortisol and potassium were detected in both affected siblings. Long-range PCR-based NGS identified a heterozygous missense variant (NM_000497.4:c.281 C > T, p.P94> L) in CYP11B1 gene in the two siblings. PCR detected no chimeric CYP11B2/CYP11B1 gene. We finally identified a second pathogenic variant in CYP11B1 gene via target long-read sequencing (T-LRS). This novel variant was a deletion-insertion variant and located chr8:143957269–143,957,579 (hg19) with the insertion of ‘ACAG’ (NM_000497.4:c.954 + 78_980delinsACAG), which was in trans with CYP11B1: c.281 C > T.ConclusionsOur study suggests that the integrated long-range PCR-based NGS and T-LRS seem to be the most reliable and accurate method for 11β-OHD genetic diagnosis and carrier sequencing.

Pathogenic cryptic variants detectable through exome data reanalysis significantly increase the diagnostic yield in Joubert syndrome.

Joubert syndrome (JS) is a genetically heterogeneous neurodevelopmental ciliopathy. Despite exome sequencing (ES), several patients remain undiagnosed. This study aims to increase the diagnostic yield by uncovering cryptic variants through targeted ES reanalysis. We first focused on 26 patients in whom ES only disclosed heterozygous pathogenic coding variants in a JS gene. We reanalyzed raw ES data searching for copy number variants (CNVs) and intronic variants affecting splicing. We validated CNVs through real-time PCR or chromosomal microarray, and splicing variants through RT-PCR or minigenes. Cryptic variants were then searched in additional 44 ES-negative JS individuals. We identified cryptic "second hits" in 14 of 26 children (54%) and biallelic cryptic variants in 3 of 44 (7%), reaching a definite diagnosis in 17 of 70 (overall diagnostic gain 24%). We show that CNVs and intronic splicing variants are a common mutational mechanism in JS; more importantly, we demonstrate that a significant proportion of such variants can be disclosed simply through a focused reanalysis of available ES data, with a significantly increase of the diagnostic yield especially among patients previously found to carry heterozygous coding variants in the KIAA0586, CC2D2A and CPLANE1 genes.

Analysis of low-density lipoprotein receptor gene mutations in a family with familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is a common monogenic autosomal dominant disorder, primarily mainly caused by pathogenic mutations in the low-density lipoprotein receptor (LDLR) gene. Through phenotypic-genetic linkage analysis, two LDLR pathogenic mutations were identified in FH families: c.G1027A (p.Gly343Ser) and c.G1879A (p.Ala627Thr). Whole exome sequencing was conducted on the proband with familial hypercholesterolemia to identify the target gene and screen for potential pathogenic mutations. The suspicious responsible mutation sites in 14 family members were analyzed using Sanger sequencing to assess genotype-phenotype correlations. Mutant and wild type plasmids were constructed and transfected into HEK293T cells to evaluate LDLR mRNA and protein expression. In parallel, bioinformatics tools were employed to predict structural and functional changes in the mutant LDLR. Immunofluorescence analysis revealed no significant difference in the intracellular localization of the p.Gly343Ser mutation, whereas protein expression of the p.Ala627Thr mutation was decreased and predominantly localized in the cytoplasm. Western blotting has showed that protein expression levels of the mutant variants were markedly declined in both cell lysates and supernatants. Enzyme linked immunosorbent assay has demonstrated that LDLR protein levels in the supernatant of cell culture medium was not significant different from those of the wild-type group. However, LDLR protein levels in the cell lysate of both the Gly343Ser and Ala627Thr variants groups were significantly lower than those in the wild-type group. Bioinformatic predictions further suggested that these mutations may affect post-translational modifications of the protein, providing additional insight into the mechanisms underlying the observed reduction in protein expression. In this study, we identified two heterozygous pathogenic variants in the LDLR gene, c.G1027A (p.Gly343Ser) and c.G1879A (p.Ala627Thr), in a family with familial hypercholesterolemia. We also conducted preliminary investigations into the mechanisms by which these mutations contribute to disease pathology.

Radiculomegaly as a key clinical feature in oculo-facio-cardio-dental (OFCD) syndrome: a case report with a novel truncating variant in BCOR gene.

Radiculomegaly is a rare dental anomaly characterised by the enlargement of the root canals of teeth. It is usually associated with oculo-facio-cardio-dental (OFCD) syndrome due to truncating variants in BCL-6 transcriptional corepressor (BCOR) (MIM*300485). We present the case of a 21-year-old female patient who was referred to genetics for a polymalformative syndrome including bilateral glaucoma and dental anomalies, especially radiculomegaly. Some others dysmorphic features were right superior lip notch, ogival palate, long philtrum, difficulty in pronation, café-au-lait spots, II-III toe bilateral syndactyly, and macrocephaly. Cone-beam CT confirmed radiculomegaly. The genetic analysis identified a heterozygous pathogenic variant NM_001123385.1:c.2093del (p.Pro698Glnfs*17) in the BCOR gene. After genetic diagnosis of OFCD syndrome, cardiac CT-scan revealed a large asymptomatic atrial septal defect that was subsequently surgically closed. Reviews of the literature have previously highlighted the prevalence of radiculomegaly in OFCD syndrome with a positive predictive value of 88.23% and a sensitivity of 75.94%. This case report highlights the importance of radiculomegaly as a clinical sign of OFCD syndrome, emphasising the rarity of non-syndromic radiculomegaly and the benefits of its diagnosis in clinical management, especially in cardiac screening.

Clinical and genetic analysis of a child with Spondyloocular syndrome due to compound heterozygous variants of XYLT2 gene

To explore the clinical characteristics and genetic etiology of a child with Spondyloocular syndrome (SOS) in order to enhance the awareness and understanding of this disease. A 3.5-year-old boy with SOS who had presented at the Department of Medical Genetics of Hunan Children's Hospital on August 10, 2023 due to the repeated fractures for over 2 years and after binocular cataract surgery was selected as the study subject. Clinical data of his pedigree were collected, and peripheral venous blood samples were collected for the extraction of genomic DNA and subjected to trio-whole exome sequencing. Candidate variants were verified by Sanger sequencing and analyzed with bioinformatic software. This study was approved by the Medical Ethics Committee of Hunan Children's Hospital (Ethics No. KYAQ2022-263). The child had manifested repeated fractures, bilateral bowed femur, osteoporosis, cataract, atrial septal defect, and developmental delay. Ultrasonography has revealed fetal edema, peritoneal effusion, pleural effusion and polyhydramnios. Trio-whole exome sequencing and Sanger sequencing revealed that he has harbored compound heterozygous variants of the XYLT2 gene, namely c.1103_1104delAG (p.Gln368Argfs*8) and c.1238_1253delinsA (p.Val413_Pro418delinsGlu), which were inherited from his phenotypically normal father and mother, respectively. Neither variant was reported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG) and recommendations from the Clinical Genome Resource (ClinGen), the c.1103_1104delAG was predicted as a pathogenic variant (PVS1+PM2_Supporting+PP4), whilst the c.1238_1253delinsA was predicted as a likely pathogenic variant (PM4+PM3+PM2_Supporting+PP4). The c.1103_1104delAG and c.1238_1253delinsA compound heterozygous variants of the XYLT2 gene probably underlay the pathogenesis in this child. Above finding has enriched the phenotypic and mutational spectrum of SOS, and provided a basis for the clinical diagnosis, treatment, prognosis assessment and genetic counseling for this pedigree.

Analysis of ACADVL gene variant in a Chinese pedigree affected with Very-long-chain acl-CoA dehydrogenase deficiency

To carry out genetic testing on a child diagnosed with Very-long-chain acyl-CoA dehydrogenase deficiency (VLADD) in order to provide a basis for genetic counseling and prenatal diagnosis for his family. Whole exome sequencing was performed for the proband. Candidate variant sites in the ACADVL gene were verified by Sanger sequencing, and their pathogenicity was predicted based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). Prenatal diagnosis was performed on the fetus upon subsequent pregnancy. This study was approved by the Luoyang Maternal and Child Health Care Hospital (Ethics No. ). The proband was found to harbor compound heterozygous variants of the ACADVL gene, namely c.1532G>A and 1827+2_1827+12del, which were inherited from his mother and father, and classified as likely pathogenic and pathogenic, respectively. By combining the clinical manifestations of the proband and the results of blood tandem mass spectrometry and genetic testing, the child was ultimately diagnosed as cardiomyopathy type VLADD. Prenatal diagnosis showed that the fetus has carried the same compound heterozygous variants, and the couple had opted to terminate the pregnancy. The c.1532G>A/1827+2_1827+12del compound heterozygous variants of the ACADVL gene probably underlay the pathogenesis of VLADD in this pedigree. The discovery of the 1827+2_1827+12del variant has enriched the mutational spectrum of the ACADVL gene.

Novel compound heterozygous variants in the TSPEAR gene causing autosomal recessive hearing loss in a Chinese family

Novel compound heterozygous variants in the <i>TSPEAR</i> gene causing autosomal recessive hearing loss in a Chinese family

Novel Compound Heterozygous Variants in the FAS Gene Lead to Fetal Onset of Autoimmune Lymphoproliferative Syndrome (ALPS).

FAS gene defects lead to autoimmune lymphoproliferative syndrome (ALPS), which is often inherited in an autosomal dominant and rarely in an autosomal recessive manner. We report a case of a newborn girl with novel compound heterozygous variants in FAS and reveal the underlying mechanism. Whole-exome sequencing (WES) was used to identify pathogenic variants. Multiparametric flow cytometry analysis, phosflow analysis, and FAS-induced apoptosis assays were used to explore the effects of the variants on FAS expression, apoptosis, and immunophenotype. The HEK293T cells were used to assess the impact of the variants on protein expression and FAS-induced apoptosis. The patient was born with hepatosplenomegaly, anemia, and thrombocytopenia. She also experienced COVID-19, rotavirus infection, herpes simplex virus infection, and severe pneumonia. The proportion of double-negative T cells (DNTs) was significantly elevated. Novel FAS compound heterozygous variants c.310T > A (p.C104S) and c.702_704del (p.T235del) were identified. The apoptotic ability of T cells was defective, and FAS expression on the surface of T cells was deficient. The T235del variant decreased FAS expression, and the C104S protein remained in the endoplasmic reticulum (ER) and could not translocate to the cell surface. Both mutations resulted in loss-of-function in terms of FAS-induced apoptosis in HEK293T cells. The DNTs were mainly terminally differentiated T (TEMRA) and CD45RA+HLA-DR+, with high expression of CD85j, PD-1, and CD57. The percentage of Th1, Tfh, and autoreactive B cells were significantly increased in the patient. The abnormal immunophenotyping was partially attenuated by sirolimus treatment. We identified two variants that significantly affect FAS expression or localization, leading to early disease onset of in the fetus. Abnormalities in the mTOR pathway are associated with a favorable response to sirolimus.

Genetic analysis of a child with autosomal recessive primary microcephaly due to variant of ASPM gene and a literature review

To explore the clinical and genetic characteristics of a child with autosomal recessive primary microcephaly (MCPH). A case study has been carried out on a boy who had presented at the Inner Mongolia Maternity and Child Health Care Hospital for microcephaly and mental deficiency in September 2022. Prenatal ultrasound images were retrospectively analyzed, and whole exome sequencing and Sanger sequencing were carried out for his family. A literature review was also carried out using keywords such as "ASPM gene", "microcephaly", "prenatal diagnosis", "primary microcephaly", "ASPM", "MCPH5", "MCPH", "autosomal recessive microcephaly", and "prenatal diagnosis on ultrasonography" on the PubMed database, Wanfang Data and China National Knowledge until September 2023. This study was approved by the Inner Mongolia Maternity and Child Health Care Hospital (Ethics No. 2021-093-1). The proband had shown progressive reduction in biparietal diameter (BPD) and head circumference (HC) during the fetal period. He was found to harbor compound heterozygous variants of the ASPM gene, which included a paternally derived c.8044C>T (p.R2682X) and a maternally derived c.8652dup (p.A2885Sfs*35). Both variants were classified as pathogenic (PVS1+PM2_Supporting+PP4; PVS1+PM2_Supporting+PM3) based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). For other fetuses in his family, prenatal ultrasound and genetic testing were all normal. Literature research has identified 11 relevant articles, which included 14 MCPH cases. All of the MCPH5 cases had shown various degrees of reduced BPD/HC on fetal imaging (100%, 15/15). Developmental delay, intellectual disability, and attention deficits were noted in all survived cases, with one case having seizures (12.5%, 1/8). Their genotypes had included homozygotes (46.2%, 6/13) and compound heterozygotes (53.8%, 7/13) for nonsense variants (45%, 9/20) and frameshifting variants (55%, 11/20). The compound heterozygous variants c.8044C>T (p.R2682X) and c.8652dup (p.A2885Sfs*35) of the ASPM gene probably underlay the reduced BPD and HC in this proband with MCPH.

Genetic variants in patients with multiple arterial aneurysms

PurposeThe aim of this study was to identify causal genetic variants in patients with multiple arterial aneurysms.MethodsFrom a total cohort of 3107 patients diagnosed with an arterial aneurysm from 2006 to 2016, patients with known hereditary connective tissue diseases, vasculitis, or other arterial pathologies (n = 918) were excluded. Of the remaining cohort (n = 2189), patients with at least 4 aneurysms at different arterial locations (n = 143) were included. Nine blood samples of respective patients were available and derived from the institutional vascular biomaterial bank, and analyzed by whole exome sequencing (WES). Possible candidate variants were selected based on in silico predictions: (I) Truncating variants or (II) Variants that were classified as likely pathogenic (SIFT score < 0.05 or PolyPhen score > 0.9) and with low (< 0.001) or unknown gnomAD allele frequency. The human genome databases GeneCards and MalaCards were used to correlate the variants with regard to possible associations with vascular diseases.ResultsA total of 24 variants in 23 different genes associated with vascular diseases were detected in the cohort. One patient with eight aneurysms was heterozygous for a variant in SMAD3, for which pathogenic variants are phenotypically associated with Loeys-Dietz syndrome 3. A heterozygous variant in TNXB was found in a patient with five aneurysms. Homozygous or compound heterozygous pathogenic variants in this gene are associated with Ehlers-Danlos syndrome (classical-like). Another patient with six aneurysms carried two heterozygous TET2 variants together with a heterozygous PPM1D variant. Pathogenic variants in these genes are associated with clonal hematopoiesis of indeterminate potential (CHIP), a known risk factor for cardiovascular disease.ConclusionAll nine patients in this study carried variants in genes associated with vascular diseases. Current knowledge of the specific variants is insufficient to classify them as pathogenic at the present time, underlining the need for a better understanding of the consequences of genetic variants. WES should be considered for patients with multiple arterial aneurysms to detect germline variants and to improve clinical management for the individual and family members.

Shwachman-Diamond syndrome due to biallelic EFL1 variants with complex and fatal clinical course in early infancy.

Shwachman-Diamond syndrome represents a clinically and genetically heterogeneous disorder. We report on an infant with a very severe, fatal clinical course caused by biallelic EFL1 variants: c.89A>G, p.(His30Arg), and c.2599A>G, p.(Asn867Asp). Functional analysis of patient-derived B-lymphoblastoid and SV40-transformed fibroblast cell lines suggests that the compound heterozygous EFL1 variants impaired mature ribosome formation leading to compromised protein synthesis, ultimately resulting in a severe form of Shwachman-Diamond syndrome.

Cost-saving approach with screening of selected variants in genetic diagnosis in Turkish pediatric familial Mediterranean fever patients: a single center longitudinal study.

The aim of this study was to investigate whether a short exon screening consisting of selected variants could confirm the diagnosis in patients with a preliminary diagnosis of familial Mediterranean fever (FMF), thus providing a cost-saving alternative to a comprehensive MEditerranean FeVer (MEFV) gene sequence analysis test. This observational study on pediatric patients focused on clinically suspected FMF cases without prior genetic analysis. Participants met the Turkish pediatric FMF criteria. They underwent short exon screening for M694V, M680I, V726A, and E148Q variants. Those who were heterozygous or negative on short exon screening received further MEFV gene sequence analysis. The study involved 1557 patients. Pathogenic variants in both alleles of the MEFV gene were found in 611 patients (39.2%), and a high-penetrance variant in heterozygosity or an E148Q variant on the other allele was found in 643 patients (41.3%). A further 189 patients (12.1%) had one or two E148Q variants. Short-exon screening was negative in 114 patients (7.6%). Of the 876 patients who underwent MEFV gene sequence analysis, additional variants were found in 72 of the 762 initially heterozygous patients. Of the 114 initially negative patients, 34 had homozygous or compound heterozygous variants, and 74 had heterozygous variants. Ultimately, only 6 patients yielded negative results in the MEFV gene sequence analysis. The short exon screening for common MEFV mutations offers a practical and cost-saving alternative to comprehensive MEFV gene sequence analysis in populations with a high prevalence of FMF.

A novel variant in the 3′ UTR of the TCF4 gene likely causes Pitt-Hopkins syndrome: a case report

BackgroundPitt–Hopkins syndrome (PTHS) is a rare neurodevelopmental disorder that results from variants of TCF4 gene. PTHS follows an autosomal dominant inheritance pattern and the underlying pathological mechanisms of this disease are still unclear.MethodsWhole-genome sequencing (WGS) was conducted to screen for potential pathogenic variant in a boy highly suspected of having a genetic disorder. PCR and Sanger sequencing were used to verify the effects of the variant. Serum TCF4 levels were measured by ELISA.ResultsWe present a 4-year and 3-month-old Chinese boy clinically and molecularly diagnosed with PTHS. The proband experienced global development delay, and the preliminary clinical diagnosis was cerebral palsy. WGS identified a de novo heterozygous variant: c.*1A > G in the 3’UTR of the TCF4 gene as a potential cause of his condition. The variant was verified to cause aberrant mRNA splicing by PCR and the aberrant splicing was confirmed by Sanger sequencing.ConclusionThe study identified and demonstrated the pathogenicity of a novel 3’UTR site TCF4 variant for the first time. This research enhances understanding of pathogenetic mechanisms of PTHS and aids genetic counseling and diagnosis.

The clinical and genetic aspects of six individuals with GH1 variants and isolated growth hormone deficiency type II.

Isolated growth hormone deficiency type II (IGHD II) is an autosomal dominant disorder characterized by a GH1 gene variant resulting in a significant reduction in growth hormone (GH) secretion and a subsequent decrease of plasma insulin-like growth factor 1 (IGF-1) levels and eventual growth impairment. This study aimed to identify causative variants in six Chinese families with IGHD II, exploring both clinical and genetic characteristics. Detailed clinical data, including clinical presentations, physical charateristics, medical and family histories, as well as genetic test results, were systematically examined. Six children, comprising four males and two females, with a mean age of 4.64 ± 1.15 years, exhibited short stature with a mean height of -3.95 ± 1.41 SDS. Four of them had a family history of short stature, while one patient presented with pulmonary hypertension. All children demonstrated GH deficiency in growth hormone stimulation tests (mean peak GH value: 2.83 ± 2.46 ng/mL). Exome sequencing for the six patients and targeted gene sequencing for their family members revealed heterozygous variants in the GH1 gene, including Exon2-5del, c.334T>C, c.291 + 1G>A, c.291 + 2T>A, 1.5 kb deletion, and 1.7 kb deletion, with four variants being novel. Four patients underwent human recombinant growth hormone (rhGH) replacement therapy, initiating treatment at a mean age of 4.6 ± 0.7 years. The mean height increase in patients was 1.21 ± 0.3 SDS in the first six months of treatment and 1.79 ± 0.15 SDS in the first year. Our findings contribute to expanding the genotypic and phenotypic spectra of individuals with IGHD II.

Novel Variant in ANO5 Muscular Dystrophy: Identification by Whole Genome Sequencing and Quad Analysis.

The phenotypic spectrum of ANO5 muscle disease ranges widely from elevated creatine kinase (CK) levels in the serum of asymptomatic individuals to progressive muscular dystrophy. Due to overlapping clinical features among muscular dystrophies, the diagnosis of ANO5 muscle disease is established by molecular genetic tests. Early diagnosis is crucial for the clinical management of symptoms and to mitigate cardiac and musculoskeletal complications. Quad-joint analysis was performed on whole genome sequencing (WGS) data obtained from an 18-year-old female with mild myalgia and elevated CK and her unaffected parents and sister. The phenotype-driven analysis was performed to prioritize genomic alterations related to the phenotype. The zygosity-based analysis investigated compound heterozygous and de novo status for all variants. The quad-joint WGS analysis revealed a novel pathogenic heterozygous variant, ANO5:c.1770_1773del (p.Phe593Metfs*15), that was paternally inherited. A second and known pathogenic heterozygous variant, ANO5:c.148C>T (p.Arg50*), was also present that was maternally inherited. The genome finding led to the diagnosis of autosomal recessive ANO5 muscle disease and an early personalized clinical management for the patient regarding her cardiac and musculoskeletal health. This is the first report of the ANO5:c.1770_1773del variant in the literature. This report highlights the spectrum of ANO5 muscle disease and describes the role of quad-joint WGS in the early diagnosis and preventive clinical management of ANO5 muscle disease.

8696 Whole Exome Sequence Analysis in a Naïve Cohort of Congenital Hypopituitarism in a Single Center

Abstract Disclosure: F.Q. Aratani: None. D.P. Di Matteo: None. I.P. de Magalhães: None. P. Frudit: None. L.S. Motomia: None. S.K. Beeby: None. L.R. Barros: None. D.D. Bissegatto: None. L.R. Carvalho: None. Background: Deficiency of one or more pituitary hormones is defined as hypopituitarism. In the literature, molecular diagnosis (MD) is defined in 12% by the Sanger sequencing and large scale sequencing increased this number to 15%. Aim: To perform whole exome sequencing (WES) in a cohort of patients with congenital hypopituitarism (CH) naïve to MD approach. Patients: Nine patients with CH followed in a single Brazilian tertiary center were included. Methods: Libraries were prepared with kits from Agilent and sequenced on Hi-Seq (Illumina). The variants were called following GATK best practices, using the Haplotypecaller and genome version hg38. They were classified in the Franklin by genoox (https://franklin.genoox.com/clinical-db/home). WES that did not pass the platform's initial quality control and variants that did not reach an adequate confidence level (low/medium confidence: VAF &amp;lt; 50%) were excluded. The remaining variants were classified according to ACMG criteria. Results: Three among 9 patients presented allelic variants and aredescribed here. Case 1: A 22-year-old female presented height of 143 cm (-3,13 SDS) at the first visit without signs of puberty, had delayed bone age (DBA), hypoplastic adenohypophysis, interrupted pituitary stalk (IPS) and ectopic neurohypophysis (ENH) at the magnetic resonance imaging (MRI). Hormonal profile showed low E2, GH, FSH and LH. Twoheterozygous missense variants in the ALMS1 gene (c.5450G&amp;gt;A : p.Arg1817GIn; and ALMS1:c.4225G&amp;gt;C: p.Ala1409Pro) were seen in the exome; both classified as VUS according to ACMG criteria. This allelic variant is related to Alstrom Syndrome. Case 2: A 7-year-old female presented with short stature and was diagnosed with GH followed by LH/FSH, TSH and ACTH deficiencies. At MRI presented IPS and ENH. A heterozygous variant in the PROK2 gene c.364C&amp;gt;T p.R122 with a premature stop codon and truncated protein was present and classified as probably pathogenic according to ACMG criteria. This variant was already described with hypogonadotropic hypogonadism (HH) with or without anosmia. Case3: A 15-year-old male was referred with growth hormone deficiency (GHD), DBA, and HH. Growth hormone replacement was started followed by testosterone. Despite delayed puberty, the testes were normal in size. WES showed a variant c.629G&amp;gt;A:p.Trp210*, in hemizygosity in IGSF1 gene and was classified as probably pathogenic according to ACMG criteria. Loss-of-function mutations in IGSF1 may cause an X-linked syndrome of central hypothyroidism, macroorchidism and delayed puberty (delayed rise of testosterone, but normal timing of testicular growth). Conclusion: WES in a cohort of patients with congenital hypopituitarism naïve to molecular diagnosis revealed 33% (3/9) with positive genetic findings, two of them with clinical significance and family segregation according to the genetic inheritance. Presentation: 6/3/2024

7640 The first description of an MC4R variant in a patient with Kallmann syndrome and obesity

Abstract Disclosure: A.A. Aslam: None. S. Lim: None. R. Willemsen: None. K. Koysombat: None. M. Young: None. W.S. Dhillo: None. A. Abbara: None. S. Howard: None. E.F. Gevers: None. Introduction: Pathogenic MC4R gene variants result in hyperphagia and early onset obesity but puberty is not usually affected. We describe an MC4R variant in a patient with Kallmann syndrome and obesity. A 16 year old male with repaired Tetralogy of Fallot, anosmia, autism and anxiety, was referred with obesity and delayed puberty. His birth weight was 3360 g (-0.26 SDS). Height was -1.31 SDS, BMI 30.7 kg/m2. He had high arched palate, normal skin and hair colour, mild hypertelorism and upward slanting palpebral fissures. Pubertal staging was A2P1G1 5ml testes bilaterally. Results: LHRH test showed borderline low peaks (LH 5.0 U/L, FSH 2.6 U/L) and inhibin B 108 pg/mL (25-325 pg/mL). MRI brain showed hypoplastic olfactory bulbs, absent olfactory sulci and normal pituitary anatomy. CGH microarray, karyotype and the UK hypogonadism gene panel were normal. He underwent whole genome sequencing in the Genetic Factors Affecting the Timing of Puberty Study; no abnormalities in 52 known genes associated with GnRH deficiency were found but a previously described heterozygous variant was detected, MC4R c.542G&amp;gt;A, p.Gly181Asp, classified pathogenic and absent in control databases. Management: He was commenced on Testosterone but showed progression of testicular size to 10 mL and testosterone was stopped but required restarting. Repeat investigations off treatment, aged 22 years (height 178 cm, BMI 42 kg/m2, testes 15 mL): inhibin B 66 pg/mL, testosterone 2 nmol/L, baseline LH 2.4 U/L, stimulated peak 24.9 U/L, baseline FSH 1.2 U/L, stimulated peak 4.2 U/L. Cortisol and IGF1 were in the normal range. He also developed autoimmune hypothyroidism with raised TPO antibodies (TSH 24.7 mU/L, FT4 5.6 pmol/L). Discussion: Previous in vitro work has shown complete loss of function of MC4R p.Gly181Asp due to reduced cell surface expression and reduced binding to a-MSH. Heterozygous p.Gly181Asp variants have been described in several children/adults with obesity; but hypogonadism in heterozygous carriers has not. Homozygous MC4R p.Gly181Asp was found in a male with obesity and partial HH thought to be due to abnormal GnRH production but with normal olfactory bulbs. We are the first to describe a heterozygous MC4R p.Gly181Asp variant in a patient with partial hypogonadism and anosmia with hypoplastic bulbs in addition to obesity. Interaction between POMC-MC-leptin circuits and Kisspeptin-GnRH circuits is recognised although not completely understood. Previous work has shown that a subset of kisspeptin neurons express MC4R and that KNDy neurones receive synaptic input from POMC neurons. In addition, inhibition of MC4R/MC3R results in delayed onset of puberty in rats. Our results support a role for MC4R in GnRH secretion and potentially olfactory /GnRH neuronal migration. Assessment of spontaneous gonadotrophin production and response of gonadotrophin production to kisspeptin stimulation is currently in progress. Presentation: 6/1/2024

9378 Knockdown Of The Cdh2 Gene In Zebrafish Determines Its Role In Terminal Hormone Differentiation

Abstract Disclosure: B.V. Fernandes: None. C. MacRae: None. L.R. Carvalho: None. M. Junqueira: None. Introduction: Congenital hypopituitarism (CH) is characterized by the deficiency of one or more pituitary hormones. Whole exome sequencing (WES) has allowed the identification of novel/rare variants in genetic diseases. Among CH patients, 85% lack a molecular diagnosis. WES approach in a patients born to consanguineous parents identified the homozygous variant (c.865G&amp;gt;A, p. Val289Ile) in the CDH2 gene that produce N-Cadherin protein responsible for cell-cell adhesion. This variant was predicted as likely pathogenic allelic variant by ACMG criteria was found in a patient with GH, TSH, ACTH, LF/FSH deficiencies associated with an ectopic neurohypophysis and pituitary hypoplasia. CDH2 analysis in a cohort of 219 patients with CH, followed in a single Brazilian center, identified 3 unrelated families with heterozygous variants and incomplete penetrance where 2 were novel, in addition to the p. Val289Ile. The deleterious effect of the homozygous variant on cell adhesion properties was confirmed in permanent transfection assays in L1 fibroblast cell lines. To determine the role of the cdh2 gene in pituitary development and hormone production and secretion, we selected zebrafish as an animal model due to its 75% genetic homology with humans. Knockout of cdh2 using Crispr/cas9 genomic edition resulted in 85% lethality of animals at 48 hours post-fertilization (hpf), precluding analysis of its role during pituitary development. Objective: To produce a cdh2 knockdown in zebrafish for phenotypic and molecular analysis. Materials and Methods: The pET28B-RfxCas13d-His plasmid was transformed, linearized, and followed by in vitro transcription to produce Cas13 mRNA. Three guide RNAs targeting the cdh2 gene were designed to guide Cas13 to the target. The Cas13/RNA guide complex was injected into single-cell embryos, and phenotypic analyses were performed under a stereomicroscope until 96 hpf. To evaluate cdh2, prop1, pit1 and gh gene expression by RT-PCR, embryos were collected at 24, 48, 72, and 96 hpf. Results: Knockdown animals exhibited microcephaly, cardiac edema, and microphthalmia during embryonic development. CDH2 expression was decreased by 75% in the first 24 hours of life and began to recover by 48 hours, gradually increasing until 96 hpf when it equaled to WT. gh expression was statistically decreased at 48h compared to WT, with an increased gh expression similar to cdh2 increasing reaching similar WT levels by 96 hpf. There was no statistically significant difference in prop1 and pit1 expression compared to WT in the analyzed periods. Conclusion: The cdh2 knockdown in zebrafish using Cas13 enzyme was effective with cdh2 decreased expression by 75% presenting a phenotype similar to the knockout model. Decreased gh expression at 48h suggests an important role of cdh2 in hormonal terminal differentiation, which should be corroborated by analysis of other hormone expressions. Presentation: 6/2/2024

8528 An Unusual Case Of Adrenal Hemorrhage As An Initial Manifestation Of Castleman Disease In A 29 yo Male With Unsuspected Late-Onset Congenital Adrenal Hyperplasia

Abstract Disclosure: L.M. Martel: None. F. Mercier: None. S. Parisien-La Salle: None. A. Lacroix: None. A. Liberman: None. N. Bettache: None. H. Olney: None. I. Bourdeau: None. Background: Castleman disease is a lymphoproliferative disorder with no clear etiology. We report the case of a 29 yo man presenting with an adrenal hemorrhage as initial manifestation of Castleman disease and unsuspected late-onset congenital adrenal hyperplasia. Clinical case: A 29-year-old male with no significant past medical history except for unilateral orchiectomy at 1 year-old for a possible testicular mass was referred to our adrenal clinic for a 6,2x7,5 cm left adrenal mass showing at CT scan necrosis and an hemorrhagic component (HU52). The patient presented initially with acute left abdominal pain. The adrenal mass showed at peripheral high uptake at PET-FDG (SUVmax 5,3) with no central uptake. His physical exam was unremarkable except for obesity. The hormonal work-up for the adrenal mass revealed normal metanephrines, and normal 1mg-dexamethasone suppression test with morning cortisol of 18 nmol/L (N&amp;lt;50). Further hormonal investigations based on the high adrenal mass uptake and possible adrenocortical carcinoma included: 17-OH Progesterone: 7.7 nmol/L (N:1.1-7.0), Androstenedione: 14.1 nmol/L (N: 1.5-9.0), Testosterone: 11.3 nmol/L (N: 9.0-28.3) and DHEAS: 3.6 umol/L (2.3-18.7). The ACTH levels were increased at 21.2 pmol/L (N:2-11) with morning cortisol of 220 nmol/L. During the consultation, the patient reported a pleuritic chest pain and underwent an urgent CT pulmonary angiography showing a pulmonary embolism with lung infarction in addition to mediastinal lymphadenopathy (biopsy negative) and a mass in his thymus. He underwent thymectomy and the pathology report described Castleman disease (hyaline vascular type). Taking into account the increased level of 17-OH progesterone, we performed an ACTH stimulation test (250 mcg) that showed an increase of cortisol levels from 333nmol/L to 874nmol/L at 60 minutes and of 17OH Progesterone levels from 5.2nmol/L to 44.2nmo/L excluding adrenal insufficiency, but confirming the diagnosis of late-onset congenital adrenal hyperplasia. Genetic analyses: After written consent, the patient underwent genetic analysis of the CYP21A2 gene by direct sequencing and MLPA. The analyses revealed a heterozygous pathogenic variant in the CYP21A2 gene (c.293-13A/C&amp;gt;G). No other genetic variant was identified in the gene. Follow-up: Subsequent adrenal MRIs showed decreasing size of the left adrenal mass; 3 cm at 3 months, 2 cm at 6 months and no residual mass was seen at 9 months supporting the diagnosis of adrenal hemorrhage. Conclusion: To our knowledge, we report a first case of Castleman disease presenting with adrenal hemorrhage as initial symptom with the association of late-onset congenital adrenal hyperplasia. The possible link between these diseases remains to be explored. Presentation: 6/3/2024