Spectrum Of Pathogenic Variants Research Articles

Congenital Myasthenic Syndromes in Belgium: Genetic and Clinical Characterization of Pediatric and Adult Patients

BackgroundCongenital myasthenic syndromes (CMS) are a group of genetic disorders characterized by impaired neuromuscular transmission. CMS typically present at a young age with fatigable muscle weakness, often with an abnormal response after repetitive nerve stimulation (RNS). Pharmacologic treatment can improve symptoms, depending on the underlying defect. Prevalence is likely underestimated. This study reports on patients with CMS followed in Belgium in 2022. MethodsData were gathered retrospectively from the medical charts. Only likely pathogenic and pathogenic variants were included in the analysis. ResultsWe identified 37 patients, resulting in an estimated prevalence of 3.19 per 1,000,000. The patients harbored pathogenic variants in CHRNE, RAPSN, DOK7, PREPL, CHRNB1, CHRNG, COLQ, MUSK, CHRND, GFPT1, and GMPPB. CHRNE was the most commonly affected gene. Most patients showed disease onset at birth, during infancy, or during childhood. Symptom onset was at adult age in seven patients, caused by variants in CHRNE, DOK7, MUSK, CHRND, and GMPPB. Severity and distribution of weakness varied, as did the presence of respiratory involvement, feeding problems, and extraneuromuscular manifestations. RNS was performed in 23 patients of whom 18 demonstrated a pathologic decrement. Most treatment responses were predictable based on the genotype. ConclusionsThis is the first pooled characterization of patients with CMS in Belgium. We broaden the phenotypical spectrum of pathogenic variants in CHRNE with adult-onset CMS. Systematically documenting larger cohorts of patients with CMS can aid in better clinical characterization and earlier recognition of this rare disease. We emphasize the importance of establishing a molecular genetic diagnosis to tailor treatment choices.

Two novel TMEM67 variations in a Chinese family with recurrent pregnancy loss: a case report

BackgroundRecurrent pregnancy loss (RPL) is a common pregnancy complication that brings great pain to pregnant women and their families. Genetic factors are an important cause reason of RPL. However, clinical research on monogenic diseases with recurrent miscarriage is insufficient.Case presentationHere we reported a Chinese family with RPL and genetic analysis of the abortion and parents. A paternally inherited heterozygous missense variant c.1415T > G (p.V472G) and a maternally inherited heterozygous nonsense variant c.2314del (p.M772*) in TMEM67 gene were identified by trio-exome sequencing. c.2314del (p.M772*) generated a premature stop codon and truncated protein, was classified as “pathogenic”. c.1415T > G (p.V472G) located in extra-cellular region, was classified as “likely pathogenic”. Biallelic variants in TMEM67 gene cause lethal Meckel syndrome 3, consistent with the proband’s prenatal phenotype.ConclusionThe current study of the Chinese family expands the pathogenic variant spectrum of TMEM67 and emphasizes the necessity of exome sequencing in RPL condition.

Novel likely pathogenic variant in the EYA1 gene causing Branchio oto renal syndrome and the exploration of pathogenic mechanisms

ObjectiveBranchio-oto-renal syndrome (BOR, OMIM#113,650) is a rare autosomal dominant disorder that presents with a variety of symptoms, including hearing loss (sensorineural, conductive, or mixed), structural abnormalities affecting the outer, middle, and inner ear, branchial fistulas or cysts, as well as renal abnormalities.This study aims to identify the pathogenic variants by performing genetic testing on a family with Branchio-oto-renal /Branchio-otic (BO, OMIM#602,588) syndrome using whole-exome sequencing, and to explore possible pathogenic mechanisms.MethodsThe family spans 4 generations and consists of 9 individuals, including 4 affected by the BOR/BO syndrome. Phenotypic information, including ear malformation and branchial cleft, was collected from family members. Audiological, temporal bone imaging, and renal ultrasound examinations were also performed. Whole-exome sequencing was conducted to identify candidate pathogenic variants and explore the underlying molecular etiology of BOR/BO syndrome by minigene experiments.ResultsIntra-familial variability was observed in the clinical phenotypes of BOR/BO syndrome in this family. The severity and nature of hearing loss varied in family members, with mixed or sensorineural hearing loss. The proband, in particular, had profound sensorineural hearing loss on the left and moderate conductive hearing loss on the right. Additionally, the proband exhibited developmental delay, and her mother experienced renal failure during pregnancy and terminated the pregnancy prematurely. Genetic testing revealed a novel heterozygous variant NM_000503.6: c.639 + 3 A > C in the EYA1 gene in affected family members. In vitro minigene experiments demonstrated its effect on splicing. According to the American College of Medical Genetics (ACMG) guidelines, this variant was classified as likely pathogenic.ConclusionThis study highlights the phenotypic heterogeneity within the same family, reports the occurrence of renal failure and adverse pregnancy outcomes in a female patient at reproductive age with BOR syndrome, and enriches the mutational spectrum of pathogenic variants in the EYA1 gene.

Novel Synonymous and Deep Intronic Variants Causing Primary and Secondary Pyruvate Dehydrogenase Complex Deficiency

Pyruvate dehydrogenase complex deficiency (PDCD) is a defect of aerobic carbohydrate metabolism that causes neurological disorders with varying degrees of severity. We report the clinical, biochemical, and molecular findings in patients with primary and secondary PDCD caused by novel atypical genetic variants. Whole-genome sequencing (WGS) identified the synonymous variants c.447A>G, p.(Lys149=) and c.570C>T, p.(Cys190=) in pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1), the deep intronic variants c.1023+2267G>A and c.1023+2302A>G in pyruvate dehydrogenase complex component X (PDHX), and c.185+15054G>A in thiamine pyrophosphokinase (TPK1). Analysis by Sanger and RNA sequencing of cDNA from patient blood and/or cultured fibroblasts showed that the synonymous variants in PDHA1 lead to aberrant splicing and skipping of exons 5 and 5-6 in one of the patients and transcripts lacking exon 6 in the other. The deep intronic variants in PDHX and TPK1 lead to insertion of intronic sequence in the corresponding transcripts. The splice defects in PDHA1 were more pronounced in cultured fibroblasts than in blood. Our findings expand the spectrum of pathogenic variants causing PDCD and highlight the importance of atypical variants leading to aberrant splicing. The severity of the splice defects and resulting biochemical dysfunction varied between tissues, stressing the importance of performing biochemical and transcript analysis in affected tissues. The two males with hemizygous synonymous PDHA1 variants have a mild phenotype and higher PDH enzyme activity than expected, which is consistent with aberrant but leaky splicing with a proportion of the transcripts remaining correctly spliced.

Cohen syndrome combined with psychiatric symptoms: a case report

BackgroundCohen syndrome (CS) is a rare autosomal recessive inherited condition characterized by pathological changes affecting multiple systems. The extensive clinical variability associated with CS poses a significant diagnostic challenge. Additionally, there is limited documentation on the co-occurrence of CS with psychiatric symptoms.Case reportWe report a case of a 30-year-old patient exhibiting characteristic physical features and psychiatric symptoms. Whole exome sequencing identified two heterozygous variants, a nonsense variation c.4336 C > T and a missense mutation c.4729G > A. Integrating clinical manifestations with genetic test results, we established the diagnosis of CS combined with psychiatric symptoms.ConclusionsThis case introduces a novel missense variant as a candidate in the expanding array of VPS13B pathogenic variants. Its clinical significance remains unknown, and further investigation may broaden the spectrum of pathogenic variants associated with the VPS13B gene. Early diagnosis of CS is crucial for the prognosis of young children and holds significant importance for their families.

Identification of new variants in patients with mucopolysaccharidosis in consanguineous Iranian families.

Introduction: Mucopolysaccharidoses are a group of lysosomal storage disorders that include seven types that are classified based on the enzymes that are disrupted. Malfunction of these enzymes leads to the accumulation of glycosaminoglycans (GAGs) in various tissues. Due to genetic and clinical heterogeneity, diagnosing and distinguishing the different types is challenging. Genetic methods such as whole exome sequencing (WES) and Sanger sequencing are accurate methods for detecting pathogenic variants in patients. Methods: Thirty-two cases of mucopolysaccharidosis, predominantly from families with consanguineous marriages, were genetically examined. Out of these, fourteen cases underwent targeted sequencing, while the rest underwent WES. The results of WES were analyzed and the pathogenicity of the variants was examined using bioinformatics tools. In addition, a segregation analysis within families was carried out. Results: In most cases, a pathogenic or likely pathogenic variant was detected. Sixteen previously reported variants and six new variants were detected in the known IDS (c.458G>C, c.701del, c.920T>G), GNS (c.1430A>T), GALNS (c.1218_1221dup), and SGSH (c.149T>C) genes. Furthermore, we discovered a c.259G>C substitution in the NAGLU gene for the first time in three homozygous patients. This substitution was previously reported as heterozygous. Except for the variants related to the IDS gene, which were hemizygous, all the other variants were homozygous. Discussion: It appears that the high rate of consanguineous marriages in the families being studied has had a significant impact on the occurrence of this disease. Overall, these findings could expand the spectrum of pathogenic variants in mucopolysaccharidoses. Genetic methods, especially WES, are very accurate and can be used alone or in conjunction with other diagnostic methods for a more precise and rapid diagnosis of mucopolysaccharidoses. Additionally, they could be beneficial for family screening and disease prevention.

Four different gene-related cone-rod dystrophy: clinical and genetic findings in six Chinese families with diverse modes of inheritance.

Purpose: To investigate pathogenic variants in six families with cone-rod dystrophy (CORD) presenting various inheritance patterns by using whole-exome sequencing (WES) and analyzing phenotypic features. Methods: A total of six families with CORD were enrolled in Ningxia Eye Hospital for this study. The probands and their family members received comprehensive ophthalmic examinations, and DNA was abstracted from patients and family members. Whole-exome sequencing was performed on probands to screen the causative variants, and all suspected pathogenic variants were determined via Sanger sequencing. Furthermore, co-segregation analysis was performed on available family members. The pathogenicity of novel variants was predicted using in silico analysis and evaluated according to the American College of Medical Genetics and Genomics (ACMG) guidelines. Results: Of the six families, two families were assigned as X-linked recessive (XL), two families were assigned as autosomal recessive (AR), and two families were assigned as autosomal dominant (AD). Pathogenic variants were detected in CACNA1F in two X-linked recessive probands, among which family 1 had a hemizygous frameshift variant c.2201del (p.Val734Glyfs*17) and family 2 had a hemizygous missense variant c.245G>A (p.Arg82Gln). Both probands had high myopia, with fundus tessellation accompanied by abnormalities in the outer structure of the macular area. The homozygous splice variant c.2373 + 5G>T in PROM1 and the homozygous nonsense variant c.604C>T (p.Arg202Ter) in ADAM9 were detected in two autosomal recessive families of the probands. Both probands showed different degrees of atrophy in the macular area, and the lesions showed hypofluorescence changes in autofluorescence. The heterozygous variation in CRX c.682C>T (p.Gln228Ter) was detected in two autosomal dominant families. The onset age of the two probands was late, with better vision and severe macular atrophy. According to ACMG guidelines and the analysis of online in silico tools, all variations were labeled as potentially harmful or pathogenic. Conclusion: Pathogenic variants in CACNA1F, PROM1, ADAM9, and CRX genes were identified in six families affected by the diverse inheritance patterns of CORD. Furthermore, the potential impact of the nonsense-mediated decay (NMD) mechanism on the manifestation of CORD phenotypes was examined and addressed. Simultaneously, the spectrum of pathogenic variants and clinical phenotypes associated with the CORD gene was extended.

Identification of the RPGR Gene Pathogenic Variants in a Cohort of Polish Male Patients with Retinitis Pigmentosa Phenotype.

The goal of the study was to explore the spectrum of pathogenic variants in the RPGR gene in a group of male Polish patients with a retinitis pigmentosa (RP) phenotype. A total of 45 male index patients, including twins, being members of 44 families, were screened for pathogenic variants in the RPGR gene via the direct sequencing of PCR-amplified genomic DNA and underwent a comprehensive ophthalmological examination in one center located in Poland. A total of two pathogenic and five likely pathogenic variants in eight patients (18%) were detected in the studied cohort. Of these, five variants were novel, and five disease-causing variants (71%) were identified within the ORF15 mutational hotspot of the RPGR gene. The median age of onset of the disease was 10 years (range 6-14 years), the median age during the examination was 30 years (range 20-47 years), and the median visual acuity was 0.4 (range 0.01-0.7). The majority of patients had middle constriction of the visual field and thinning of the central foveal thickness. Dizygotic twins bearing the same hemizygous mutation showed a different retinal phenotype in regard to the severity of the symptoms. This is the first RPGR mutation screening in Poland showing a prevalence of 18% of RPGR pathogenic mutations and likely pathogenic variants in the studied cohort of male patients with an RP phenotype.

Comprehensive Genetic Analysis Unraveled the Missing Heritability and a Founder Variant of BEST1 in a Chinese Cohort With Autosomal Recessive Bestrophinopathy.

To describe the genetic landscape of BEST1 for a large Chinese cohort with autosomal recessive bestrophinopathy (ARB), identify the missing heritability, and report a common Chinese founder variant. We recruited 65 patients from 63 families with a clinical diagnosis of ARB. All patients underwent ophthalmic examinations and comprehensive genetic analyses, including Sanger DNA sequencing of BEST1 and whole genome sequencing (WGS). The effects of deep intronic variants (DIVs) on splicing were assessed using in vitro splicing assays in HEK293T cells and patient-derived peripheral blood mononuclear cells. Haplotype mapping was performed for 17 unrelated patients harboring variant c.867+97G>A. We identified 54 distinct disease-causing variants of BEST1 in 63 pedigrees, 62probands with biallelic variants, and one family with monoallelic variants. Sanger DNA sequencing of BEST1 initially detected 51 variants in 61 pedigrees, including 19probands with one heterozygous variant. Subsequent WGS, combined with supplementary Sanger sequencing, revealed three missing DIVs (c.1101-491A>G, c.867+97G>A, and c.867+97G>T) in 20 families. The novel DIV c.1101-491A>G caused an abnormal splicing resulting in a 204-nt pseudoexon (PE) insertion, whereas c.867+97G>A/T relatively strengthened an alternative donor site, resulting in a 203-nt intron retention (IR). The PE and IR generated a premature termination codon downstream. Haplotype analysis identified c.867+97G>A as a common founder variant with an allele frequency of 16%. Our results expand the pathogenic variant spectrum of BEST1, and DIVs can explain almost all of the missing heritability. The c.867+97G>A DIV is a common founder variant for Chinese patients with ARB.

Novel Variants of PPP2R1A in Catalytic Subunit Binding Domain and Genotype-Phenotype Analysis in Neurodevelopmentally Delayed Patients.

Neurodevelopmental disorders (NDDs) are a group of high-incidence rare diseases with genetic heterogeneity. PPP2R1A, the regulatory subunit of protein phosphatase 2A, is a recently discovered gene associated with NDDs. Whole/clinical exome sequencing was performed in five patients with a family with NDDs. In vitro experiments were performed to evaluate the mutants' expression and interactions with the complex. The genotype-phenotype correlations of reported cases as well as our patients with PPP2R1A variants were reviewed. We reported five unrelated individuals with PPP2R1A variants, including two novel missense variants and one frameshift variant. The protein expression of the Arg498Leu variant was less than that of the wild-type protein, the frameshift variant Asn282Argfs*14 was not decreased but truncated, and these two variants impaired the interactions with endogenous PPP25RD and PPP2CA. Furthermore, we found that pathogenic variants clustered in HEAT repeats V, VI and VII, and patients with the Met180Val/Thr variants had macrocephaly, severe ID and hypotonia, but no epilepsy, whereas those with Arg258 amino acid changes had microcephaly, while a few had epilepsy or feeding problems. In this study, we reported five NDD patients with PPP2R1A gene variants and expanded PPP2R1A pathogenic variant spectrum. The genotype and phenotype association findings provide reminders regarding the prognostication and evidence for genetic counseling.

AIOLOS haploinsufficiency is associated with immunodeficiency, autoimmunity, and allergy

AIOLOS is a transcription factor of the IKAROS family, that is highly expressed in the lymphoid lineage and plays an important role in lymphocyte differentiation and development. Recently, two heterozygous AIOLOS germline mutations (G159R and N160S) were reported in primary immunodeficiency patients. Both variants associated distinctive and unique T and B cell differentiation defects, hematologic malignancies, and infectious disease susceptibility patterns through different dominant negative (DN) mechanisms. Here we report seven individuals from three unrelated families carrying AIOLOS variants Q402* (nonsense, 1 family) and E82K (missense, 2 families), leading to AIOLOS haploinsufficiency through different mechanisms of action. Clinically, patients with AIOLOS haploinsufficiency showed hypogammaglobulinemia, recurrent respiratory tract infections, and immune dysregulation manifested by autoimmunity and allergy, with incomplete clinical penetrance. Mechanistically, while the nonsense mutant Q402* is devoid of its C-terminal zinc-finger (ZF) dimerization domain (ZF5-6), it is still able to homodimerize with wildtype (WT) AIOLOS although unable to heterodimerize with WT IKAROS or HELIOS. We introduce new insights into AIOLOS biology as we found that AIOLOS ZF1, a part of AIOLOS DNA binding domain (ZF1-4), was associated with noncanonical dimerization and negative regulation of DNA binding. Further studies revealed that the mutant Q402* displayed abnormalities of DNA binding, pericentromeric targeting, post-transcriptional modification, and transcriptome regulation by haploinsufficiency. In contrast, mutant E82K showed overall normal AIOLOS functions; however, by affecting a newly defined AIOLOS protein stability domain, it also led to AIOLOS haploinsufficiency. Unlike the previously reported AIOLOS mutations, heterozygous variants Q402* and E82K do not have a DN effect over other IKAROS family proteins. Our data extend the spectrum of pathogenic variants of AIOLOS-associated diseases and provide a novel mechanism of homodimerization and protein stability that, when disrupted, could affect human health.

Clinical and genetic analysis of cases of progressive familial intrahepatic cholestasis type 3

Objective: To conduct clinical and genetic analysis in two cases of cholestatic liver disease to determine the specific etiology of cholestasis. Methods: Clinical data and the medical histories in family members of two cases were collected. The gene variation was detected by whole-exome sequencing technology. Sanger sequencing validation and bioinformatics analysis were performed on patients and their parents with suspected pathogenic mutations. Results: Whole-exome sequencing showed that the ABCB4 gene of case 1 (a male, 16 years old) had compound heterozygous mutations of c.646C > T from the father and c.927T > A from the mother, while the ABCB4 gene of case 2 (a female, 17 years old) had a compound heterozygous mutation of c.2784-1G > A from the father and c.646C > T from the mother. New mutation sites that had not been previously reported were c.646C > T, c.927T > A, and c.2784-1G > A. Conclusion: In this study, both cases had progressive familial intrahepatic cholestasis type 3 (PFIC-3) caused by ABCB4 gene mutations, and it also enriched the ABCB4 pathogenic variant spectrum. Whole-exome sequencing technology provides a reliable diagnostic tool for etiological analysis.

Genotypic and phenotypic characterisation of RP2- and RPGR- associated X-linked inherited retinal dystrophy, including female manifestations.

With the promise of gene replacement therapy, eligible males and females with X-linked inherited retinal dystrophy (XL-IRD) should be identified. Retrospective observational cohort study to establish the phenotypic and genotypic spectrum of XL-IRD within New Zealand (NZ). Thirty-two probands, including 9 females, with molecularly proven XL-IRD due to RP2 or RPGR mutations, and 72 family members, of which 43 were affected, were identified from the NZ IRD Database. Comprehensive ophthalmic phenotyping, familial cosegregation, genotyping, and bioinformatics were undertaken. Main outcome measures were: RP2 and RPGR pathogenic variant spectrum, phenotype in males and females (symptoms, age of onset, visual acuity, refraction, electrophysiology, autofluorescence, retinal appearance), and genotype-phenotype correlation. For 32 families, 26 unique pathogenic variants were identified; in RP2 (n=6, 21.9% of all families), RPGR exons 1-14 (n=10, 43.75%), and RPGR-ORF15 (n=10, 34.3%). Three RP2 and 8 RPGR exons 1-14 variants are novel, rare, and cosegregate. Thirty-one% of carrier females were significantly affected, with 18.5% of families initially classified as autosomal dominant. Of 5 Polynesian families, 80% had novel disease-causing variants. One Māori family showed keratoconus segregating with an ORF15 variant. Significant disease was present in 31% of genetically proven female carriers, often leading to an erroneous presumption of the inheritance pattern. Pathogenic variants in 44% of the families were in exon 1-14 of RPGR, more frequent than usually described, which may inform the gene testing algorithm. Proving cosegregation in families for novel variants and identifying affected females and males translates to optimised clinical care and potential for gene therapy.

Analysis of molecular genetics and clinical characteristics of 3 children with Waardenburg syndrome

Objective:To analyze the molecular genetics and clinical characteristics of 3 children with syndromic deafness were analyzed to clarify their causative genes and genetic characteristics. Methods:The medical records of 3 children and their parents were collected and analyzed, including physical examination, hearing evaluation, temporal bone CT, and cranial MRI. Whole-exome sequencing（WES） was used to screen for pathogenic gene variants, and Sanger sequencing was used to verify the candidate positive variants in the probands and their parents. Results:All 3 patients were female with normal intelligence. Patient 1 and 3 had a family history of deafness, which conformed to the pattern of autosomal dominant inheritance. All three patients had bilateral profound sensorineural hearing impairment with bright-blue sclera. Other phenotypes included hypertelorism（patient 1）, multiple dyschromatosis（patient 2）, and yellowish hair（patient 2）, blepharoptosis（patient 3）. Patient 3 had bilateral vestibular enlargement, internal auditory canal enlargement, and bilateral inner ear malformations. Mother of patient 1 had only left mild hearing impairment; mother of patient 3 had bilateral hearing impairment with unilateral bright-blue sclera and yellowish hair. WES detected heterozygous variants, PAX3 c.811C>T, MITF c.632T>C, and SOX10 c.1359_1360 insGCCCCACA, in patient 1, 2, and 3, respectively. The variants in patient 1 and 3 were inherited from their mothers who had hearing impairment, and MITFvariant in patient 2 may be a spontaneous variation. The final diagnoses were that patient 1 with Waardenburg syndrome type 1（WS1）, and the mother of patient 1, patient 2, patient 3, and the mother of patient 3 with WS2. Conclusion:WS is a syndromic deafness, and the main clinical features include autosomal dominant inheritance and scleral pigment abnormalities. However, the findings of this study show that there is still phenotypic heterogeneity in WS even caused by the same gene variant, so it depends on genetic tests to confirm the diagnosis; The gene variant of patient 1 and 2 was never been reported in other patients, which expands the pathogenic variant spectrum of WS.

Novel pathogenic variants in the androgen receptor gene associated with androgen insensitivity syndrome identified through exome sequencing and in silico analysis

Androgen insensitivity syndrome (AIS) is a common disorder/differences of sex development with a 46, XY karyotype, but diverse genital phenotypes. Various pathogenic variants within the androgen receptor (AR) gene on the X chromosome are the primary pathogenesis of AIS. However, some patients with AIS still lack a definitive molecular diagnosis. Here, molecular diagnosis of eight patients with the clinical phenotype of AIS was performed using exome sequencing. We found eight variants of the AR gene, including p.(C131*), p.(W435*), p.(T653Lfs*8), c.2318+1G>T, p.(S397R), p.(Y572C), p.(S648G), and p.(D691G), and a pathogenic copy number variation covering a deletion of exon 2 of AR gene. Patient pedigree validation confirmed that the discovered variants conformed to the X-linked recessive inheritance patterns of AIS. In silico analysis indicated that the splice site variant (c.2318+1G>T) could lead to loss of the original 5′ splice donor site and exon skipping. Missense variants, including p.(S397R), p.(S648G), and p.(D691G), may affect the structure and function of the AR protein. Our results highlight the applicability of exome sequencing for molecular diagnosis of AIS. The novel variants found in this study enrich the pathogenic variant spectrum of the AR gene and provide a basis for the diagnosis and management of patients with AIS. A definite molecular diagnosis will provide accurate guidance for genetic counseling of proband’s family members.

Clinical features and genetic analysis of two Chinese pedigrees affected with Joubert syndrome

To explore the clinical characteristics and genetic basis of two Chinese pedigrees affected with Joubert syndrome. Clinical data of the two pedigrees was collected. Genomic DNA was extracted from peripheral blood samples and subjected to high-throughput sequencing. Candidate variants were verified by Sanger sequencing. Prenatal diagnosis was carried out for a high-risk fetus from pedigree 2. The proband of pedigree 1 was a fetus at 23+5 weeks gestation, for which both ultrasound and MRI showed "cerebellar vermis malformation" and "molar tooth sign". No apparent abnormality was noted in the fetus after elected abortion. The fetus was found to harbor c.812+3G>T and c.1828G>C compound heterozygous variants of the INPP5E gene, which have been associated with Joubert syndrome type 1. The proband from pedigree 2 had growth retardation, mental deficiency, peculiar facial features, low muscle tone and postaxial polydactyly of right foot. MRI also revealed "cerebellar dysplasia" and "molar tooth sign". The proband was found to harbor c.485C>G and c.1878+1G>A compound heterozygous variants of the ARMC9 gene, which have been associated with Joubert syndrome type 30. Prenatal diagnosis found that the fetus only carried the c.485C>G variant. A healthy infant was born, and no anomalies was found during the follow-up. The compound heterozygous variants of the INPP5E and ARMC9 genes probably underlay the disease in the two pedigrees. Above finding has expanded the spectrum of pathogenic variants underlying Joubert syndrome and provided a basis for genetic counseling and prenatal diagnosis.

Analysis of genotypes and phenotypes of three children with Cornelia de Lange syndrome

To analyze the clinical phenotype and results of genetic testing in three children with Cornelia de Lange syndrome (CdLS). Clinical data of the children and their parents were collected. Peripheral blood samples of the pedigrees were collected for next generation sequencing analysis. The main clinical manifestations of the three children have included growth delay, mental retardation, peculiar facies and other accompanying symptoms. Based on the criteria proposed by the International Diagnostic Consensus, all three children were suspected for CdLS. As revealed by whole exome sequencing, child 1 has harbored NIPBL gene c.5567_5569delGAA insTAT missense variant, child 2 has harbored SMC1A gene c.607A>G missense variant, and child 3 has harbored HDAC8 gene c.628+1G>A splicing variant. All of the variants were de novo in origin. All of the children were diagnosed with CdLS due to pathogenic variants of the associated genes, among which the variants of NIPBL and HDAC8 genes were unreported previously. Above finding has enriched the spectrum of pathogenic variants underlying CdLS.

Genomic Profiling Reveals the Variant Landscape of Sporadic Parathyroid Adenomas in Chinese Population.

To define somatic variants of parathyroid adenoma (PA) and to provide novel insights into the underlying molecular mechanism of sporadic PA. Basic clinical characteristics and biochemical indices of 73 patients with PA were collected. Whole-exome sequencing was performed on matched tumor-constitutional DNA pairs to detect somatic alterations. Functional annotation was carried out by ingenuity pathway analysis afterward. The protein expression of the variant gene was confirmed by immunohistochemistry, and the relationship between genotype and phenotype was analyzed. Somatic variants were identified in 1549 genes, with an average of 69 variants per tumor (range, 13-2109; total, 9083). Several novel recurrent somatic variants were detected, such as KMT2D (15/73), MUC4 (14/73), POTEH (13/73), CD22 (12/73), HSPA2 (12/73), HCFC1 (11/73), MAGEA1 (11/73), and SLC4A3 (11/73), besides the previously reported PA-related genes, including MEN1 (11/73), CASR (6/73), MTOR (4/73), ASXL3 (3/73), FAT1 (3/73), ZFX (5/73), EZH1 (2/73), POT1 (2/73), and EZH2 (1/73). Among them, KMT2D might be the candidate driver gene of PA. Crucially, 5 patients carried somatic mutations in CDC73, showed an aggressive phenotype similar to that of parathyroid carcinoma (PC), and had a decreased expression of parafibromin. Pathway analysis of recurrent potential PA-associated driver variant genes revealed functional enrichments in the signaling pathway of Notch. Our study expanded the pathogenic variant spectrum of PA and indicated that KMT2D might be a novel candidate driver gene and be considered as a diagnostic biomarker for PA. Meanwhile, CDC73 mutations might be an early developmental event from PA to PC. The results provided insights into elucidating the pathogenesis of parathyroid tumorigenesis and a certain basis for clinical diagnosis and treatment.

A novel missense ALMS1 variant causes aberrant splicing identified in a cohort of patients with Alström syndrome.

Purpose: Alström syndrome (AS) is a rare autosomal recessive disorder caused by variants of ALMS1. The objectives of this study were to describe the clinical and genetic characteristics of 19 Chinese patients with biallelic variants in ALMS1. Methods: We recruited 19 probands with biallelic disease-causing ALMS1 variants. All patients underwent ophthalmic and systematic evaluations and comprehensive molecular genetic analysis. Reverse transcriptase-polymerase chain reaction (RT-PCR) assays were performed to observe the effect of a novel missense variant on ALMS1 pre-mRNA splicing. Results: We identified 33 causative variants in ALMS1, including 15 frameshift small indels, 14 non-sense variants, two gross deletions, one splicing variant, and one missense variant. RT-PCR showed that the missense variant c.9542G>A (p.R3181Q) altered pre-mRNA splicing to generate a truncated protein p. (Ser3082Asnfs*6). Retinal dystrophy (RD) was noted in all the patients, followed by metabolism disturbance (obesity or acanthosis nigricans) in 66.7% and hearing impairment in 61.1% of the patients. Patient systemic symptom numbers and their age at evaluation showed a significant positive correlation, and BCVA and age at the last examination showed a moderate correlation. All patients exhibited early-onset RD and severe visual impairment. The exception was one patient carrying homozygous p. R3181Q, who showed a mild visual defect and atypical retinal phenotype. Conclusion: Our findings expand the pathogenic variant spectrum of ALMS1 and provide the first verification of a novel missense variant caused AS by aberrant pre-mRNA splicing. Patients with AS might demonstrate varied clinical spectra; therefore, genetic analysis is vital for the early and accurate diagnosis of patients with atypical AS.

Pathogenic Variant Spectrum in Breast Cancer Risk Genes in Finnish Patients.

Recurrent pathogenic variants have been detected in several breast and ovarian cancer (BC/OC) risk genes in the Finnish population. We conducted a gene-panel sequencing and copy number variant (CNV) analysis to define a more comprehensive spectrum of pathogenic variants in BRCA1, BRCA2, PALB2, CHEK2, ATM, BARD1, RAD51C, RAD51D, BRIP1, and FANCM genes in Finnish BC patients. The combined frequency of pathogenic variants in the BRCA1/2 genes was 1.8% in 1356 unselected patients, whereas variants in the other genes were detected altogether in 8.3% of 1356 unselected patients and in 12.9% of 699 familial patients. CNVs were detected in 0.3% of both 1137 unselected and 612 familial patients. A few variants covered most of the pathogenic burden in the studied genes. Of the BRCA1/2 carriers, 70.8% had 1 of 10 recurrent variants. In the other genes combined, 92.1% of the carrier patients had at least 1 of 11 recurrent variants. In particular, PALB2 c.1592delT and CHEK2 c.1100delC accounted for 88.9% and 82.9%, respectively, of the pathogenic variation in each gene. Our results highlight the importance of founder variants in the BC risk genes in the Finnish population and could be used in the designing of population screening for the risk variants.