[Clinical features and VPS33B mutations in a family affected by arthrogryposis, renal dysfunction, and cholestasis syndrome]

[Rare VPS33B gene mutation combined with GP1BA mutation causes severe decrease in plasma VWF levels: a case report and literature review]

A 28-year-old woman was found to have coagulation factor Ⅷ activity (FⅧ∶C) <1% and von Willebrand factor antigen (VWF∶Ag) <1% during routine prenatal examinations. No pathogenic variation was found in the exon region of the VWF gene using next-generation sequencing. The clinical presentation of this patient does not match the clinical characteristics of type Ⅲ hemophilia [von Willebrand disease (VWD) ]; therefore, third-generation sequencing technology was used to perform whole-genome sequencing on the patient and her family members. Multiple members of the patient's paternal family carried a heterozygous variant of VPS33B, c.869G>C. The family members carrying this variant all had varying degrees of reduced VWF levels (39% -56% ). Moreover, the proband was detected with the heterozygous variant c.1474dupA in GP1BA. The ACMG and Clinvar databases determined that this variation was associated with platelet-type pseudo VWD. The decrease in VWF levels caused by heterozygous variations in VPS33B in families is the first international report, and no previous studies have reported cases of severe decrease in plasma VWF levels caused by double heterozygous variations in VPS33B and GP1BA.

[Clinical features and LAMA2 mutations of patients with congenital muscular dystrophy type 1A: a case report and literature review]

Biallelic pathogenic mutations of the LAMA2 gene result in congenital muscular dystrophy type 1A (CMD1A). The patient in this study was a boy aged 19 months, with the clinical manifestations of motor development delay and increases in the serum levels of creatine kinase, aminotransferases, and lactate dehydrogenase. Genetic analysis showed that the patient had compound heterozygous mutations in the LAMA2 gene, among which c.7147C>T (p.Ala2383Ter) from his mother was a known nonsense mutation, and c.8551_8552insAA (p.Ile2852ArgfsTer2) from his father was a frameshift mutation which had never been reported before and was identified as a pathogenic mutation based on the ACMG guideline. The boy was confirmed with CMD1A. A literature review of related articles in China and overseas revealed that most children with CMD1A have disease onset within 6 months after birth, with the features of motor developmental delay, elevated serum creatine kinase, and white matter impairment on imaging examination. The mutations of the LAMA2 gene have remarkable heterogeneity, the majority of which are null mutations. There are no specific treatment methods for CMD1A currently, and children with CMD1A usually have a poor long-term prognosis.