Novel Pathogenic Mutation Mapping of ASPM Gene in Consanguineous Pakistani Families with Primary Microcephaly

Autosomal recessive primary microcephaly (MCPH) is a neurodevelopmental disorder characterized by a congenitally reduced head circumference (-3 to -5 SD) and non-progressive intellectual disability. The objective of the study was to evaluate pathogenic mutations in the ASPM gene to understand etiology and molecular mechanism of primary microcephaly. Blood samples were collected from various families across different remote areas of Pakistan from February 2017 to May 2019 who were identified to be affected with primary microcephaly. DNA extraction was performed using the salting-out method; the quality and quantity of DNA were evaluated using spectrophotometry and 1% agarose gel electrophoresis, respectively in University of the Punjab. Mutation analysis was performed by whole exome sequencing from the Cologne Center for Genomics, University of Cologne. Sanger sequencing was done in University of the Punjab to confirm the pathogenic nature of mutation. A novel 4-bp deletion mutation c.3877_3880delGAGA was detected in exon 17 of the ASPM gene in two primary microcephaly affected families (A and B), which resulted in a frame shift mutation in the gene followed by truncated protein synthesis (p.Glu1293Lysfs*10), as well as the loss of the calmodulin-binding IQ domain and the Armadillo-like domain in the ASPM protein. Using the in-silico tools Mutation Taster, PROVEAN, and PolyPhen, the pathogenic effect of this novel mutation was tested; it was predicted to be “disease causing,” with high pathogenicity scores. One previously reported mutation in exon 24 (c.9730C>T) of the ASPM gene resulting in protein truncation (p.Arg3244*) was also observed in family C. Mutations in the ASPM gene are the most common cause of MCPH in most cases. Therefore, enrolling additional affected families from remote areas of Pakistan would help in identifying or mapping novel mutations in the ASPM gene of primary microcephaly.

A Novel Heterozygous Pathogenic Variation in CYCS Gene Cause Autosomal Dominant Non-Syndromic Thrombocytopenia 4 in a Large Chinese Family

Aim: To determine the etiology of a Chinese family with thrombocytopenia by analyzing the clinical features and genetic variation.Methods: Clinical profiles and genomic DNA extracts of the family members were collected for the study. Whole exome sequencing and Sanger sequencing was used to detect the associated genetic variation and verify the family co-segregation respectively. Bioinformatics analysis assessed the pathogenicity of missense mutations.Results: The study reported a 3-generation pedigree including eight family members with thrombocytopenia. The platelet counts of the patients were varied, ranging from 38 to 110 × 109/L (reference range: 150–450 x 109/L). The mean volumes and morphology of the sampled platelet were both normal. The bleeding abnormality and mitochondriopathy were not observed in all the patients. Clinical signs of thrombocytopenia were mild. A novel heterozygous missense variant c.79C > T (p.His27Tyr) was identified in CYCS gene associated with autosomal dominant thrombocytopenia.Conclusion: We report the first large family with autosomal dominant non-syndromic thrombocytopenia 4 in a Chinese family, a novel heterozygous missense variant c.79C > T (p.His27Tyr) was identified. The whole exome sequencing is an efficient tool for screening the variants specifically associated with the disease. The finding enriches the mutation spectrum of CYCS gene and laid a foundation for future studies on the correlation between genotype and phenotype.

Detection of a novel PAX6 variant in a Chinese family with multiple ocular abnormalities

Background Aniridia is a congenital, panocular disease that can affect the cornea, anterior chamber angle, iris, lens, retina and optic nerve. PAX6 loss-of-function variants are the most common cause of aniridia, and variants throughout the gene have been linked to a range of ophthalmic abnormalities. Furthermore, particular variants at a given site in PAX6 lead to distinct phenotypes. This study aimed to characterize genetic variants associated with congenital aniridia in a Chinese family. Methods The proband and family underwent ophthalmologic examinations. DNA was sampled from the peripheral blood of all 6 individuals, and whole-exome sequencing was performed. Sanger sequencing was used to verify the variant in this family members. Results A novel variant (c.114_119delinsAATTTCC: p.Pro39llefsTer17) in the PAX6 gene was identified in subjects II-1, III-1 and III-2, who exhibited complete aniridia and cataracts. The proband and the proband’s brother also had glaucoma, high myopia, and foveal hypoplasia. Conclusions We identified that a novel PAX6 frameshift heterozygous deletion variant is the predominant cause of aniridia in this Chinese family. Trial registration We did not perform any health-related interventions for the participants.

Whole-Exome Sequencing in 10 Unrelated Patients with Syndromic Hidradenitis Suppurativa: A Preliminary Step for a Genotype-Phenotype Correlation

<b><i>Background:</i></b> The genetics of syndromic hidradenitis suppurativa (HS), an immune-mediated condition associated with systemic comorbidities such as inflammatory bowel diseases and arthritis, has not been completely elucidated. <b><i>Objective:</i></b> To describe clinical features and genetic signature of patients with the main syndromic HS forms, i.e., PASH, PAPASH, and PASH/SAPHO overlapping. <b><i>Methods:</i></b> Whole-exome sequencing (WES) approach was performed in ten patients with syndromic HS. <b><i>Results:</i></b> Three clinical settings have been identified based on presence/absence of gut and joint inflammation. Four PASH patients who had also gut inflammation showed three different variants in <i>NOD2</i> gene, two variants in <i>OTULIN</i>, and a variant in <i>GJB2</i>, respectively. Three PAPASH and three PASH/SAPHO overlapping patients who had also joint inflammation showed two different variants in <i>NCSTN</i>, one in <i>WDR1</i> and <i>PSTPIP1</i>, and two variants in <i>NLRC4</i>, one of whom was present in a patient with a mixed phenotype characterized by gut and joint inflammation. <b><i>Limitations:</i></b> Limited number of patients that can be counterbalanced by the rarity of syndromic HS. <b><i>Conclusion:</i></b> Syndromic HS can be considered as a polygenic autoinflammatory condition; currently WES is a diagnostic tool allowing more accurate genotype-phenotype correlation.

A GP1BA Variant in a Czech Family with Monoallelic Bernard-Soulier Syndrome

Bernard-Soulier syndrome (BSS) is a rare inherited disorder characterized by unusually large platelets, low platelet count, and prolonged bleeding time. BSS is usually inherited in an autosomal recessive (AR) mode of inheritance due to a deficiency of the GPIb-IX-V complex also known as the von Willebrand factor (VWF) receptor. We investigated a family with macrothrombocytopenia, a mild bleeding tendency, slightly lowered platelet aggregation tests, and suspected autosomal dominant (AD) inheritance. We have detected a heterozygous GP1BA likely pathogenic variant, causing monoallelic BSS. A germline GP1BA gene variant (NM_000173:c.98G > A:p.C33Y), segregating with the macrothrombocytopenia, was detected by whole-exome sequencing. In silico analysis of the protein structure of the novel GPIbα variant revealed a potential structural defect, which could impact proper protein folding and subsequent binding to VWF. Flow cytometry, immunoblot, and electron microscopy demonstrated further differences between p.C33Y GP1BA carriers and healthy controls. Here, we provide a detailed insight into its clinical presentation and phenotype. Moreover, the here described case first presents an mBSS patient with two previous ischemic strokes.

Disruption of PIKFYVE causes congenital cataract in human and zebrafish

Congenital cataract, an ocular disease predominantly occurring within the first decade of life, is one of the leading causes of blindness in children. However, the molecular mechanisms underlying the pathogenesis of congenital cataract remain incompletely defined. Through whole-exome sequencing of a Chinese family with congenital cataract, we identified a potential pathological variant (p.G1943E) in PIKFYVE, which is located in the PIP kinase domain of the PIKFYVE protein. We demonstrated that heterozygous/homozygous disruption of PIKFYVE kinase domain, instead of overexpression of PIKFYVEG1943E in zebrafish mimicked the cataract defect in human patients, suggesting that haploinsufficiency, rather than dominant-negative inhibition of PIKFYVE activity caused the disease. Phenotypical analysis of pikfyve zebrafish mutants revealed that loss of Pikfyve caused aberrant vacuolation (accumulation of Rab7+Lc3+ amphisomes) in lens cells, which was significantly alleviated by treatment with the V-ATPase inhibitor bafilomycin A1 (Baf-A1). Collectively, we identified PIKFYVE as a novel causative gene for congenital cataract and pinpointed the potential application of Baf-A1 for the treatment of congenital cataract caused by PIKFYVE deficiency.

Case Report: Hemophagocytic Lymphocytosis in a Patient With Glutaric Aciduria Type IIC

Hemophagocytic lymphocytosis (HLH) is a rare disease caused by inborn errors of immunity (IEI), secondary to infection, lymphoma or autoimmune disorders, but we often overlook the fact that HLH can be secondary to inborn errors of metabolism (IEM). Here, we describe a patient who was diagnosed with glutaric aciduria type IIC complicated by features suggestive of possible HLH. The diagnosis of glutaric aciduria type IIC, a IEM, was confirmed by whole exome sequencing. The patient was treated with coenzyme Q10 and riboflavin which effectively improved her liver function. During treatment, the patient developed severe anemia and thrombocytopenia. Persistent fever, splenomegaly, cytopenias, increased ferritin, hypertriglyceridemia, hypofibrinogenemia, and hemophagocytosis in the bone marrow pointed to the diagnosis of HLH; however, the patient eventually died of gastrointestinal bleeding. After other potential causes were ruled out, the patient was diagnosed with glutaric aciduria type IIC complicated by features suggestive of possible HLH. When cytopenias occurs in IEM patients, HLH is a possible complication that cannot be ignored. This case suggests a possible relationship between IEM and risk for immune dysregulation.