Hemizygous Mutation Research Articles

Sensitivity to targeted UBA1 inhibition in a myeloid cell line model of VEXAS syndrome

AbstractSomatic UBA1 mutations in hematopoietic cells are a hallmark of Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic (VEXAS) syndrome, which is a late-onset inflammatory disease associated with bone marrow failure and high mortality. The majority of UBA1 mutations in VEXAS syndrome comprise hemizygous mutations affecting methionine-41 (M41), leading to the expression of UBA1M41T, UBA1M41V, or UBA1M41L and globally reduced protein polyubiquitination. Here, we used CRISPR-Cas9 to engineer isogenic 32D mouse myeloid cell lines expressing hemizygous Uba1WT or Uba1M41L from the endogenous locus. Consistent with prior analyses of VEXAS syndrome patient samples, hemizygous Uba1M41L expression was associated with loss of the UBA1b protein isoform, gain of the UBA1c protein isoform, reduced polyubiquitination, abnormal cytoplasmic vacuoles, and increased production of interleukin-1β and inflammatory chemokines. Vacuoles in Uba1M41L cells contained a variety of endolysosomal membranes, including small vesicles, multivesicular bodies, and multilamellar lysosomes. Uba1M41L cells were more sensitive to the UBA1 inhibitor TAK243. TAK243 treatment promoted apoptosis in Uba1M41L cells and led to preferential loss of Uba1M41L cells in competition assays with Uba1WT cells. Knock-in of a TAK243-binding mutation, Uba1A580S, conferred TAK243 resistance. In addition, overexpression of catalytically active UBA1b in Uba1M41L cells restored polyubiquitination and increased TAK243 resistance. Altogether, these data indicate that loss of UBA1b underlies a key biochemical phenotype associated with VEXAS syndrome and renders cells with reduced UBA1 activity vulnerable to targeted UBA1 inhibition. Our Uba1M41L knock-in cell line is a useful model of VEXAS syndrome that will aid in the study of disease pathogenesis and the development of effective therapies.

ЭФФЕКТИВНОСТЬ ТЕРАПИИ ИНГИБИТОРАМИ АНГИОТЕНЗИН- ПРЕВРАЩАЮЩЕГО ФЕРМЕНТА В ПРОФИЛАКТИКЕ РАЗВИТИЯ ПРОТЕИНУРИИ У МАЛЬЧИКОВ С Х-СЦЕПЛЕННЫМ СИНДРОМОМ АЛЬПОРТА: ДАННЫЕ ОДНОЦЕНТРОВОГО КОГОРТНОГО НЕРАНДОМИЗИРОВАННОГО ИССЛЕДОВАНИЯ

Patients with a hemizygous mutation in the COL4A5 gene have a high risk of developing renal failure at a young age. Proteinuria reflects the progression of glomerulopathy in Alport syndrome (AS). In order to improve renal survival in AS patients with proteinuria are prescribed with angiotensin system inhibitors. There is a limited, insufficient number of studies demonstrating the effectiveness of angiotensin-converting enzyme inhibitors (ACEI) in children with AS; the therapeutic effect initiated prior to the development of proteinuria has not been studied as yet. The purpose of the research was to determine the effectiveness of ACEI therapy in the form of enalapril in the prevention of proteinuria in boys with X-linked AS (XLAS). Materials and methods used: boys aged 2 to 15 y/o with genetically confirmed XLAS were included in a single-center prospective cohort study. Enalapril was prescribed at doses of 1 to 3 mg/m2/day. Urinary protein excretion (Pr) and estimated glomerular filtration rate (eGFR) were studied at the time of inclusion and with a frequency of one time per six months for the three-year period or longer. The primary endpoint was the time of onset of proteinuria. Results: 72 boys in total, incl. 29 without proteinuria, who received enalapril therapy (Group 1, age 6.2±1.9 y/o, Pr 67±20 mg/m2/day, eGFR 118±15.2 ml /min/1.73 m2) and 43 children without therapy (Group 2, age 6.8±1.9 y/o, Pr 87±23 mg/m2/day, eGFR 119±17.3 ml/min/1.73 m2). The incidence of proteinuria (0.45 in G1 vs. 0.98 in G2, p<0.001), incl. up to the age of 10 y/o (0.42 vs 0.91, respectively, p<0.001) was statistically significantly lower in G1. Proteinuria developed later in the treatment group (10.2±2.9 vs. 4.9±1.4 years, p=0.300). Non-missense mutations in the COL4A5 gene, episodes of macrohematuria in records and lack of therapy were the risk factors for proteinuria; the lack of enalapril therapy was a predictor for proteinuria. The risk of proteinuria during therapy was reduced by 50% (RR=0.46 (95% CI 0.31; 0.68); ARR=0.53; NNT=1.9). Conclusion: initiation of enalapril therapy at the pre-proteinuria stage of nephropathy in boys with XLAS reduces the risk of proteinuria preventing its occurrence in every 50$ of cases when receiving treatment. Early initiation of therapy may be effective in preventing the progression of kidney disease in boys with XLAS.

An insertion mutation of the MECP2 gene in severe neonatal encephalopathy and ocular and oropharyngeal dyskinesia: a case report

BackgroundPathogenic variation of the MECP2 gene presents mostly as Rett syndrome in females and is extremely rare in males. Most male patients with MECP2 gene mutation show MECP2 duplication syndrome.Case presentationHere we report a rare case in a 10-month-old boy with a hemizygous insertion mutation in MECP2 as NM_001110792, c.799_c.800insAGGAAGC, which results in a frameshift mutation (p.R267fs*6). The patient presented with severe encephalopathy in the neonatal period, accompanied by severe development backwardness, hypotonia, and ocular and oropharyngeal dyskinesia. This is the first report of this mutation, which highlights the phenotype variability associated with MECP2 variants.ConclusionsThis case helps to expand the clinical spectrum associated with MECP2 variants. Close attention should be paid to the growth and development of patients carrying a MECP2 variant or Xq28 duplication. Early interventions may help improve symptoms to some certain extent.

Novel mutations in CYBB Gene Cause X-linked chronic Granulomatous Disease in Pakistani patients

BackgroundChronic Granulomatous Disease (CGD) is a primary immunodeficiency that causes susceptibility to recurrent fungal and bacterial infections. The CYBB gene encodes gp91phox component of the Phagocytic Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and specifically, X-linked CGD is caused by mutations in the CYBB gene, located on the X chromosome. The aim of the study was to characterize functional and genetic mutations in X-linked CGD.MethodsFunctional analysis was conducted on the whole blood of seventeen male individuals who were suspected to have X-linked chronic granulomatous disease (CGD). Flow cytometry was employed to assess the capacity of NADPH oxidase, measuring both H2O2 production and gp91phox protein expression in neutrophils. Additionally, DNA Sanger sequencing was performed for genetic analysis. The pathogenicity of novel mutations was assessed by pathogenicity prediction tools.ResultAmong the seventeen patients evaluated, five patients (P1, P2, P3, P4, and P5) displayed impaired H2O2 production by their neutrophils upon stimulation with Phorbol myristate acetate (PMA), accompanied by abnormal gp91phox expression. DNA sequencing of the CYBB gene identified specific mutations in each patient. In P1 and P2 (previously reported cases), a hemizygous missense mutation, c.925G > A/p.E309K was identified. In P3 and P4 (novel cases), hemizygous nonsense mutations, c.216T > A/p.C72X were found. Lastly, in P5 (also a novel case), a hemizygous missense mutation, c.732T > G/p.C244W was detected. These mutations reside in exons 9,3 and 7 of the CYBB gene, respectively.ConclusionsThe current study contributes to the understanding of the clinical and genetic spectrum associated with X-linked chronic granulomatous disease (CGD). It highlights the significance of early diagnosis in CGD and emphasizes the importance of lifelong prophylaxis to prevent severe infections.

Novel XIAP mutation with early-onset Crohn’s disease complicated with acute heart failure: a case report

BackgroundThe X-linked inhibitor of apoptosis (XIAP) protein is encoded by the XIAP gene and is critical for multiple cell responses and plays a role in preventing cell death. XIAP mutations are associated with several diseases, primarily including hemophagocytic lymphohistiocytosis and inflammatory bowel disease (IBD). We report the clinical features and results associated with hemizygous mutation of the XIAP gene in a young male with Crohn’s disease complicated with acute heart failure.This 16-year-old patient ultimately died of heart failure.Case presentationA young male of 16 years of age was initially diagnosed with Crohn’s disease based on evidences from endoscopic and histological findings. Although supportive care, anti-infective drugs and biologics were administered consecutively for 11 months, his clinical manifestations and laboratory indices (patient’s condition) did not improved. Additionally, the patient exhibited a poor nutritional status and sustained weight loss. Subsequently, acute heart failure led to the exacerbation of the patient’s condition. He was diagnosed with wet beriberi according to thiamine deficiency, but the standard medical therapy for heart failure and thiamine supplementation did not reverse the adverse outcomes. Comprehensive genetic analysis of peripheral blood-derived DNA revealed a novel hemizygous mutation of the XIAP gene (c.1259_1262 delACAG), which was inherited from his mother.ConclusionA novel XIAP mutation (c.1259_1262 delACAG) was identified in this study. It may be one of the potential pathogenic factors in Crohn’s disease and plays an important role in the progression of heart failure. Additionally, thiamine deficiency triggers a vicious cycle.

Clinical and Genetic Findings in Korean Patients with Choroideremia.

We share and analyze the clinical presentations and genotypes of Korean male patients and female carriers who visited our clinic. Six male patients and three female carriers with comprehensive ophthalmic examinations and next-generation sequencing were included. Detailed clinical features were identified using visual field (VF) test and multimodal imaging including color fundus photography, fundus autofluorescence (FAF), optical coherence tomography (OCT). Six male patients were diagnosed with choroideremia at the median age of 25 years. Before genetic testing, three (50.0%) patients were clinically diagnosed with choroideremia, while the other three (50.0%) patients with retinitis pigmentosa (RP). Patients showed different types of hemizygous CHM mutation, including two nonsense mutations (c.715C>T, p.Arg239Ter; c.799C>T, p.Arg267Ter), two frameshift mutations (c.1584_1587del, p.Val529HisfsTer7; c.403_404delGA, p.Asp135PhefsTer9), one splicing mutation (c.1511-28_1511-2del), and one exon duplication (2-9). The latter three mutations are novel findings. Two female carriers showed exon duplication (2-9) and the other one female carrier showed nonsense mutations (c.715C>T, p.Arg239Ter) in heterozygote form. Fundus showed diffuse yellow-whitish scleral reflex and granular pigmented lesions. FAF showed multiple patchy hypofluorescence lesions, sparing macula. OCT showed thinning of outer nuclear layer, ellipsoid zone, RPE layer, choroid thickness, interlaminar bridges (ILBs), outer retinal tubulations (ORTs), and microcysts in the inner nuclear layer. VF showed ring scotoma pattern with small amount of remaining central field. Asymptomatic female carriers showed variable fundus findings and mild changes in OCT. A detailed description of the genotypes with three novel mutations and phenotypes of six choroideremia patients and three CHM mutation female carriers are presented.

Novel mutations in genes of the IL-12/IFN-γ axis cause susceptibility to tuberculosis

BackgroundThe IL-12/23/ISG15-IFN-γ pathway is the main immunological pathway for controlling intra-macrophagic microorganisms such as Mycobacteria, Salmonella, and Leishmania spp. Consequently, upon mutations in genes of the IL-12/23/ISG15-IFN-γ pathway cause increased susceptibility to intra-macrophagic pathogens, particularly to Mycobacteria. Therefore, the purpose of this study was to characterize the mutations in genes of the IL-12/23/ISG15-IFN-γ pathway in severe tuberculosis (TB) patients. MethodsClinically suspected TB was initially confirmed in four patients (P) (P1, P2, P3, and P4) using the GeneXpert MTB/RIF and culturing techniques. The patients' Peripheral blood mononuclear cells (PBMCs) were then subjected to ELISA to measure Interleukin 12 (IL-12) and interferon gamma (IFN-γ). Flow cytometry was used to detect the surface expressions of IFN-γR1 and IFN-γR2 as well as IL-12Rβ1and IL-12Rβ2 on monocytes and T lymphocytes, respectively.The phosphorylation of signal transducer and activator of transcription 1(STAT1) on monocytes and STAT4 on T lymphocytes were also detected by flow cytometry. Sanger sequencing was used to identify mutations in the IL-12Rβ1, STAT1, NEMO, and CYBB genes. ResultsP1's PBMCs exhibited reduced IFN-γ production, while P2's and P3's PBMCs exhibited impaired IL-12 induction. Low IL-12Rβ1 surface expression and reduced STAT4 phosphorylation were demonstrated by P1's T lymphocytes, while impaired STAT1 phosphorylation was detected in P2's monocytes. The impaired IκB-α degradation and abolished H2O2 production in monocytes and neutrophils of P3 and P4 were observed, respectively. Sanger sequencing revealed novel nonsense homozygous mutation: c.191 G>A/p.W64 * in exon 3 of the IL-12Rβ1 gene in P1, novel missense homozygous mutation: c.107 A>T/p.Q36L in exon 3 of the STAT1 gene in P2, missense hemizygous mutation:: c.950 A>C/p.Q317P in exon 8 of the NEMO gene in P3, and nonsense hemizygous mutation: c.868 C>T/p.R290X in exon 8 of CYBB gene in P4. ConclusionOur findings broaden the clinical and genetic spectra associated with IL-12/23/ISG15-IFN-γ axis anomalies. Additionally, our data suggest that TB patients in Pakistan should be investigated for potential genetic defects due to high prevalence of parental consanguinity and increased incidence of TB in the country.

Familial Whole Exome Sequencing Study of 30 Families With Early-Onset High Myopia.

This study was conducted to investigate potential candidate pathogenic genes in early-onset high myopia (eoHM) in families with eoHM. Whole-exome sequencing was performed on probands with eoHM to identify potential pathogenic genes. Sanger sequencing was used to verify the identified gene mutations causing eoHM in first-degree relatives of the proband. The identified mutations were screened out by bioinformatics analysis combined with segregation analysis. A total of 131 variant loci, involving 97 genes, were detected in the 30 families. A total of 28 genes (37 variants), which were carried by 24 families, were verified and analyzed by Sanger sequencing. We identified five genes and 10 loci associated with eoHM, which have not been reported in previous research. Hemizygous mutations in COL4A5, NYX, and CACNA1F were detected in this study. Inherited retinal disease-associated genes were found in 76.67% (23/30) of families. Genes that can be expressed in the retina in the Online Mendelian Inheritance in Man database were found in 33.33% (10/30) of families. Mutations in the genes associated with eoHM, including CCDC111, SLC39A5, P4HA2, CPSF1, P4HA2, and GRM6, were detected. The mutual correlation between candidate genes and phenotype of fundus photography was revealed in our study. The eoHM candidate gene mutation types contain five categories: missense mutations (78.38%), nonsense (8.11%), frameshift mutation (5.41%), classical splice site mutation (5.41%), and initiation codon mutation (2.70%). Candidate genes carried by patients with eoHM are closely related to inherited retinal diseases. Genetic screening in children with eoHM facilitates the early identification and intervention of syndromic hereditary ocular disorders and certain hereditary ophthalmopathies.

Acute, Transient, Brain Lesions on Magnetic Resonance Imaging in X-linked Charcot-Marie-Tooth type 1 (P13-4.002)

<h3>Objective:</h3> NA <h3>Background:</h3> CMTX1 is an X-linked dominant form of hereditary sensorimotor polyneuropathy. It is caused by mutations in the gap junction protein beta 1(GJB1) gene on chromosome Xq13.1, which encodes connexin 32 protein. CNS can be affected and lead to transient or persistent CNS symptoms including dysarthria, dysphagia, hemiparesis or quadriparesis, ataxia, aphasia, and encephalopathy. <h3>Design/Methods:</h3> <h3>Case Report:</h3> A 22-year-old man presented with acute onset left facial droop, dysarthria and left upper extremity weakness. Two weeks prior he experienced a one-day episode of gastroenteritis. Neurological examination showed weakness in the left lower face, distal muscle weakness in toe extension, ankle dorsiflexion and hand intrinsic muscles, absent lower extremity reflexes, diminished vibration and temperature senses in length-dependent pattern, high-arched feet and hammertoes. Family history of early onset polyneuropathy, never genetically tested. Brain MRI showed marked and symmetric restricted diffusion lesions involving bilateral fronto-parietal white matter, corpus callosum and posterior limb of internal capsule without contrast enhancement. CSF analysis was unremarkable. The patient was given pulse steroid therapy for possible demyelinating disease, his symptoms completely resolved within 48 hours. Two prior similar symptoms, one was diagnosed as acute disseminated encephalomyelitis (ADEM) and treated with steroids. Brain MRI of these two episodes showed similar restricted diffusion abnormalities. Repeat brain MRI seven months after the second episode showed complete resolution of restricted diffusion lesions. Leukodystrophy genetic panel was negative. Genetic testing showed hemizygous pathogenic mutation c.491G&gt;A in GJB1 gene, associated with X-linked Charcot-Marie-Tooth disease - CMTX1. <h3>Results:</h3> NA <h3>Conclusions:</h3> Young patients with history of polyneuropathy presenting with acute CNS symptoms with bilateral white matter and corpus callosum lesions, CMTX1 should be included in the differential diagnosis. Upon confirmation of CMTX1 diagnosis, patient reassurance is important as well as education regarding potential provoking factors that lead to CNS involvement. <b>Disclosure:</b> Dr. Altarazi has nothing to disclose. Dr. Chen has nothing to disclose. Dr. Sankaraneni has nothing to disclose.

Impaired bone strength and bone microstructure in a novel early-onset osteoporotic rat model with a clinically relevant PLS3 mutation.

Plastin 3 (PLS3), a protein involved in formation of filamentous actin (F-actin) bundles, is important in human bone health. Recent studies identify PLS3 as a novel bone regulator and PLS3 mutations can lead to a rare monogenic early-onset osteoporosis. However, the mechanism of PLS3 mutation leading to osteoporosis is unknown, and its effective treatment strategies have not been established. Here, we have constructed a novel rat model with clinically relevant hemizygous E10-16del mutation in PLS3 (PLS3E10-16del/0) that recapitulates the osteoporotic phenotypes with obviously thinner cortical thickness, significant decreases in yield load, maximum load, and breaking load of femora at 3, 6, 9 months old compared to wild-type rats. Histomorphometric analysis indicates a significantly lower mineral apposition rate in PLS3E10-16del/0 rats. Treatment with alendronate (1.0 µg/kg/day) or teriparatide (40 µg/kg five times weekly) for 8 weeks significantly improves bone mass and bone microarchitecture, and bone strength is significantly increased after teriparatide treatment (p＜0.05). Thus, our results indicate that PLS3 plays an important role in the regulation of bone microstructure and bone strength, and we provide a novel animal model for the study of X-linked early-onset osteoporosis. Alendronate and teriparatide treatment could be a potential treatment for early-onset osteoporosis induced by PLS3 mutation.

Splicing abnormalities caused by a novel mutation in the PHKA2 gene in children with glycogen storage disease type IX

Objective: Glycogen storage disease type IX (GSD-IX) is a rare primary glucose metabolism abnormality caused by phosphorylase kinase deficiency and a series of pathogenic gene mutations. The clinical characteristics, gene analysis, and functional verification of a mutation in a child with hepatomegaly are summarized here to clarify the pathogenic cause of the disease. Methods: The clinical data of a child with GSD-IX was collected. Peripheral blood from the child and his parents was collected for genomic DNA extraction. The patient's gene diagnosis was performed by second-generation sequencing. The suspected mutations were verified by Sanger sequencing and bioinformatics analysis. The suspected splicing mutations were verified in vivo by RT-PCR and first-generation sequencing. Results: Hepatomegaly, transaminitis, and hypertriglyceridemia were present in children. Liver biopsy pathological examination results indicated glycogen storage disease. Gene sequencing revealed that the child had a c.285 + 2_285 + 5delTAGG hemizygous mutation in the PHKA2 gene. Sanger sequencing verification showed that the mother of the child was heterozygous and the father of the child was of the wild type. Software such as HSF3.1 and ESEfinder predicted that the gene mutation affected splicing. RT-PCR of peripheral blood from children and his mother confirmed that the mutation had caused the skipping of exon 3 during the constitutive splicing of the PHKA2 gene. Conclusion: The hemizygous mutation in the PHKA2 gene (c.285 + 2_285 + 5delTAGG) is the pathogenic cause of the patient's disease. The detection of the novel mutation site enriches the mutation spectrum of the PHKA2 gene and serves as a basis for the family's genetic counseling.

Abstract 23: Development of a biallelicDicer1mutant mouse strain for studying the pathogenesis of DICER1 syndrome-associated cancer

Abstract DICER1 encodes a RNase III enzyme that post-transcriptionally controls gene expression through governing microRNA (miRNA) biogenesis. We and others have demonstrated that somatic mutations of DICER1 at its RNase IIIb domain metal binding sites, impairing its capability to produce mature miRNAs from the 5P strand of miRNA precursors, occur recurrently in a broad spectrum of cancers associated with the DICER1 syndrome that affects children and youths predominantly. The biallelic DICER1 mutations in these cancers challenge the two-hit hypothesis theory of traditional tumour suppressors, but it remains unproven whether these mutations are sufficient to drive tumorigenesis. The lack of biology relevant preclinical models has also hindered the understanding the pathogenesis. Here, we developed a genetically engineered mouse strain that expresses an inducible knockin Dicer1 missense mutation (Dicer1+/fl-D1693N), equivalent to the DICER1 RNase IIIb hotspot mutation D1709N in human cancers. This conditional strain behaves as a null allele due to an aberrant splicing event without Cre-mediated recombination. When crossed with a well-characterized conditional null Dicer1 strain (Dicer1fl/fl), the resulting compound heterozygous strain (Dicer1fl/fl-D1693N), acts as a hemizygous wildtype allele that is converted to a hemizygous missense mutation allele upon Cre-mediated recombination, reflecting the genetic status of DICER1 in DICER1 syndrome-associated cancer. When crossing with the anti-Mullerian hormone receptor 2 (Amhr2) driven cre strain (Amhr2+/cre), the biallelic Dicer1 mutation resulted in infertility in females by impairing the development of oviduct and endometrium and ultimately drove the development of multicystic tubal and intra-uterine tumours. Histologically, these murine tumors resemble human Müllerian adenosarcoma and other DICER1 syndrome-associated sarcomas. Molecular analysis of these murine tumours validated the miRNA biogenesis defects in 5P-miRNA production, uncovered the activation of the myc signaling and identified that loss of let-7 family miRNAs may drive the transcriptomic rewiring and malignant transformation. Thus, this first DICER1 syndrome-associated murine cancer model faithfully recapitulates the biology of human cancer and provides a unique tool for future investigation and therapeutic development. Citation Format: Yemin Wang, Shary Chen, Janine Senz, Maxwell Douglas, Shelby Thornton, Yana Moscovitz, C. Blake Gilks, David Huntsman, Gregg Morin. Development of a biallelicDicer1mutant mouse strain for studying the pathogenesis of DICER1 syndrome-associated cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 23.

Diagnostic Pitfalls of a Newborn with Congenital Nephrogenic Diabetes Insipidus.

Congenital nephrogenic diabetes insipidus (NDI) is a rare cause of hypernatremia in newborns. Central diabetes insipidus (CDI) is the main differential diagnosis of NDI. NDI responds poorly to desmopressin acetate (DDAVP) treatment while this is the mainstay of CDI management. Therefore, an early and correct diagnosis of NDI is crucial to avoid the complications of inappropriate therapy. Here, we report a newborn with hypernatremia and hypotonic polyuria. The patient was initially responsive but subsequently unresponsive to intranasal DDAVP treatment in regard to urine output and serum sodium levels. A novel hemizygous missense mutation (c.632T>C, p.L211P) in the AVPR2 gene was found both in the baby and his mother, and the diagnosis of congenital NDI was established. After hydrochlorothiazide treatment and hypo-osmolar formula were given, urine volume was decreased, and serum sodium levels were normalized. Early recognition and appropriate management of NDI can prevent complications of hypernatremic dehydration in young infants.

Mutation of FLNA attenuating the migration of abdominal muscles contributed to Melnick-Needles syndrome (MNS) in a family with recurrent miscarriage.

Filamin A, encoded by the X-linked gene FLNA, links the cell membrane with the cytoskeleton and acts as a regulator of the actin cytoskeleton. Mutations in FLNA cause a large spectrum of congenital malformations during embryonic development, including Melnick-Needles syndrome (MNS). However, reports of MNS, especially in males, are rare, and the pathogenesis molecular mechanisms are not well understood. We found a family with two consecutive miscarriages of similar fetuses with multiple malformations. DNA was extracted from peripheral blood and tissues, and whole exome sequencing was performed for genetic analysis. Then, we created a C57BL/6 mouse with a point mutation by CRISPR/Cas-mediated genome engineering. The migration of primary abdominal muscle cell was detected by wound healing assay. The first fetus showed congenital hygroma colli and omphalocele identified by ultrasound at 12 wks; the second fetus showed hygroma colli and thoraco abdominoschisis at 12 wks, with a new hemizygous mutation c.4420G>A in exon 26 of the FLNA gene, which is predicted to cause an amino acid substitution (p.Asp1474Asn). The mother and grandmother were both present in the c.4420G>A heterozygous state, and the mother's healthy brother had wild-type FLNA. These FLNA-mutated mice exhibited a broader central gap between the rectus abdominis than the wild type (WT), similar to the midline structure dysplasia of the abdominal wall in the two fetuses. Wound healing assays showed the attenuated migration capacity of abdominal muscle cells in mice with mutated FLNA. Finally, we summarized the cases of MNS with FLNA mutation from the accessible published literature thus far. Our research revealed a mutation site of the FLNA for MNS and explored the mechanism of midline structure dysplasia in the abdominal wall of male patients, which could provide more evidence for the clinical diagnosis and genetic counseling of families with these disorders.

PLP1 gene mutations cause spastic paraplegia type 2 in three families.

Spastic paraplegia type 2 (SPG2) is an X-linked recessive (XLR) form of hereditary spastic paraplegia (HSP) caused by mutations in proteolipid protein 1 (PLP1) gene. We described the clinical and genetic features of three unrelated families with PLP1 mutations and reviewed PLP1-related cases worldwide to summarize the genotype-phenotype correlations. The three probands were 23, 26, and 27 years old, respectively, with progressively aggravated walking difficulty as well as lower limb spasticity. Detailed physical examination showed elevated muscle tone, hyperreflexia, and Babinski signs in lower limbs. Brain MRI examinations were investigated for all cases. PLP1 mutations were identified by whole exome sequencing, followed by Sanger sequencing, family co-segregation, and phenotypic reevaluation. A total of eight patients with SPG2 were identified in these three families. The probands additionally had cognitive impairment, urinary or fecal incontinence, ataxia, and white matter lesions (WML)in periventricular regions, with or without kinetic tremor. Three hemizygous mutations in PLP1 were identified, including c.453+159G>A, c.834A>T (p.*278C), and c.434G>A (p.W145*), of which c.834A>T was first associated with HSP. We identified three families with complicated SPG2 due to three PLP1 mutations. Our study supports the clinically inter-and intra-family heterogeneity of SPG2. The periventricular region WML and cognitive impairment are the most common characteristics. The kinetic tremor in upper limbs was observed in 2/3 families, suggesting the spectrum of PLP1-related disorders is still expanding.

Generation of an induced pluripotent stem cell (iPSC) line (BBANTWi009-A) from a Meester-Loeys syndrome patient carrying a BGN mutation

Meester-Loeys syndrome (MRLS) is an X-linked syndromic form of thoracic aortic aneurysm and dissection. Here, we report an iPSC line (BBANTWi009-A) of a boy carrying a hemizygous BGN mutation (chrX:153502980-153530518del, GRCh38) causing MRLS. iPSCs were generated from dermal fibroblasts by reprogramming with the Cytotune®-iPS 2.0 Sendai Reprogramming Kit (Invitrogen). The generated iPSCs showed a normal karyotype, expressed pluripotency markers, were differentiated into the three germ layers and carried the original genotype.

378 VERY-LATE THROMBUS-RELATED STROKE AFTER PERCUTANEOUS PFO CLOSURE: MEDICAL MANAGEMENT OF A RARE COMPLICATION

Abstract In May 2020, a 45-years-old woman was admitted to the Emergency Department due to transient ischemic attack. The thrombophilia screening showed hemizygous prothrombin gene mutation (Factor II) and homozygous MTHFR mutation. The transthoracic echocardiography was normal, with a left ventricular ejection fraction of 60% and no morphological or functional valve disease. The 24-h Holter ECG and the past medical history did not show any specific cause of the neurologic manifestations. In the absence of a specific and plausible cause of the transient ischemic attack, a diagnosis of cryptogenic stroke was made. The patient then underwent transcranial Doppler, which showed a high-grade shunt (curtain effect), and transesophageal echocardiography with bubble test, which showed the presence of a massive right-to-left shunt through a patent foramen ovale (PFO) during the Valsalva maneuver. A therapy with warfarin (achieving a target INR between 2 and 3) was therefore started, and the indication for a percutaneous PFO closure was given. In January 2021 the patient underwent successful percutaneous PFO closure with the Gore Cardioform Septal Occluder 25/25 mm (W.L. Gore and Associates, Inc.) through intracardiac echocardiographic guidance with no complication and without any residual shunt. The patient was discharged on dual antiplatelet therapy with aspirin 100 mg daily plus clopidogrel 75 mg daily for six months, and pantoprazole 20 mg daily, followed by aspirin 100 mg daily chronically. After 6 months the patient underwent transcranial Doppler, which was negative for shunt. 12 months after the implantation the patient stopped aspirin by her own initiative. In August 2022, due to the diagnosis of an ovarian cyst, the gynecologist prescribed estro-progestogen pill: in that occasion, the patient did not mention her thrombophilia. After 10 days, sudden onset of weakness of the right upper limb and aphasia. The patient was then admitted to the Emergency Department, were the computer tomography showed two acute lesions on the left cerebral hemisphere. Therefore, the patient underwent intravenous thrombolysis, with complete regression of the neurological symptoms: a diagnosis of stroke was then formulated. To understand the origin of such stroke, the neurologist gave indication to cardiological evaluation. The patient did not have any palpitation in the previous months and the electrocardiogram showed normal sinus rhythm. However, the transthoracic echocardiographic evaluation showed a dubious image of a mass attached to the interatrial septum, for which the patient underwent transesophageal echocardiography, which showed a 10×9 mm fluctuating thrombus attached to the left side of the previously implanted PFO closure device. Therefore, an oral anticoagulation therapy with warfarin plus a subcutaneous therapy with enoxaparin 6000 UI twice daily (as bridge to obtain the desired INR between 2 and 3) was started. After ten days, the patient underwent a new transesophageal echocardiography, which showed a substantial reduction in the dimensions of the thrombus (4×3 mm). The patient was then discharged in warfarin therapy with no residual neurological symptoms.

Deficiency of cancer/testis antigen gene CT55 causes male infertility in humans and mice.

The Cancer/Testis Antigen (CTA) genes comprise a group of genes whose expression under physiological conditions is restricted to the testis but is activated in many human cancers. Depending on the particular expression pattern, the CTA genes are speculated to play a role in spermatogenesis, but evidence is limited thus far. Here, we reported patients with a hemizygous nonsense mutation in cancer-testis antigen 55 (CT55) suffering from male infertility with extreme disruption in sperm production, morphology, and locomotion. Specifically, the insufficiency of sperm individualization, excessive residue of unnecessary cytoplasm, and defects in acrosome development were evident in the spermatozoa of the patients. Furthermore, mouse models with depletion of Ct55 showed accelerated infertility with age, mimicking the defects in sperm individualization, unnecessary cytoplasm removal, and meanwhile exhibiting the disrupted cumulus-oocyte complex penetration. Mechanistically, our functional experiments uncovered CT55 as a new autophagic manipulator to regulate spermatogenesis via selectively interacting with LAMP2 and GABARAP (which are key regulators in the autophagy process) and further fine-tuning their expression. Therefore, our findings revealed CT55 as a novel CTA gene involved in spermatogenesis due to its unprecedented autophagy activity.

A novel splicing mutation in 5'UTR of GJB1 causes X-linked Charcot-Marie-tooth disease.

Charcot-Marie-Tooth (CMT) disease is the most frequent hereditary motor sensory neurological disease. GJB1 gene is the second most frequent cause of CMT, accounting for approximately 10% of CMT cases worldwide. We identified a large Han family with X-linked CMT disease. In this study, the probands and his mother underwent electrophysiological examinations and other family members were assessed retrospectively. Whole-exome sequencing, Sanger sequencing, and SNP array linkage analysis were performed to find and confirm the variant. The functional effect of the identified variant was further investigated in HEK293 cells and MCF-7 cells by minigene splicing assay. The affected individuals had some clinical symptoms including symmetric atrophy and progressive weakness of the distal muscles in their twenties. Electrophysiological examinations result in peripheral nerve injury of the upper and lower limbs. Whole-exome sequencing identified a novel hemizygous deletion mutation (NM_000166: c.-16-8_-14del) in the GJB1 gene. SNP array linkage analysis and co-segregation analysis confirmed this mutation. Minigene splicing assay verified that this mutation leads to the activation of cryptic splicing sites in exon 2 which results in the deletion of exon 2. Our study provides theoretical guidance for prenatal diagnosis and subsequent fertility of this family. This result expands the spectrum of mutations in GJB1 known to be associated with CMTX and contributes to the diagnosis of CMT and clinical genetic counseling.

A generation of human-induced pluripotent stem cell line (MUi032-A) from a Choroideremia disease patient carrying a hemizygous mutation on the CHM gene

Choroideremia (CHM) is a monogenic, X-linked inherited retinal disease caused by mutations in the CHM gene. CHM patients develop progressive loss of vision due to degeneration of cell layers in the retina. In this report, the human-induced pluripotent stem cell, MUi032-A, was generated from CD34+ hematopoietic stem/progenitor cells of a male CHM patient by co-electroporation of non-integration episomal vectors containing OCT4/shp53, Sox-2/KLF4, and L-MYC/LIN-28. The MUi032-A showed normal karyotype and a hemizygous c.715C > T mutation. They expressed pluripotency markers and differentiated into cells derived from three germ layers. This cell line may be useful for disease mechanisms and gene therapy studies.