PINK1 p.K520RfsX3 mutation identified in a Chinese family with early-onset Parkinson's disease

Identification of BAG5 as a Potential Biomarker for Parkinson’s Disease Patients With R492X PINK1 Mutation

Parkinson’s disease (PD) is a degenerative, progressive nervous system disorder with an unknown cause. PINK1 [phosphatase and tensin homolog deleted on chromosome 10 (PTEN)-induced putative kinase 1] causative mutations R492X may cause autosomal recessive early-onset parkinsonism. In this study, we utilized patient samples and cell line system to investigate roles of Bcl2-associated athanogene 5 (BAG5) in PD patients with R492X PINK1 mutation. We show that the expression levels of BAG5 in the skin tissues from PD patients with R492X PINK1 mutation are markedly lower than those from the healthy control subjects in a small cohort of patients, which has not been recognized before. In addition, we demonstrate that BAG5 physically binds to R492X mutated PINK1 protein. Furthermore, we reveal that BAG5 promotes the degradation of R492X mutated PINK1 protein via ubiquitin/proteasome-dependent pathway, suggesting that decreased level of BAG5 may lead to R492X mutated PINK1 protein accumulation. These findings suggest that BAG5 may serve as an early detection biomarker for PD patients with R492X PINK1 mutation and provide important new insights on how BAG5 affects R492X mutated PINK1 protein, highlighting therapeutic targets for this disease.

Identification of a frame shift mutation in the CCDC151 gene in a Han-Chinese family with Kartagener syndrome

Kartagener syndrome (KS), a subtype of primary ciliary dyskinesia (PCD), is characterized by bronchiectasis, chronic sinusitis, male infertility and situs inversus. KS is a genetically heterogeneous disease that is inherited in an autosomal recessive form; however, X-linked inheritance has also been reported. As of this writing [late 2020], at least 34 loci, most of which have known genes, have been reported in the literature as associating with KS. In the present study, we identified a frame shift mutation, c.167delG (p.G56Dfs*26), in the coiled-coil domain containing 151 gene (CCDC151) responsible for KS in a Han-Chinese family. To our knowledge, this is the first report of a CCDC151 c.167delG mutation in the KS patient. These findings may expand the CCDC151 mutation spectrum of KS, and contribute to future genetic counseling and gene-targeted therapy for this disease.

Identifying a BRCA2 c.5722_5723del mutation in a Han-Chinese family with breast cancer

Breast cancer (BC) is the most common female cancer found worldwide. It is responsible for 25% of all cancer patients in females. Hereditary BC accounts for about 5–10% of all BC cases. The breast cancer 1 gene (BRCA1) and the breast cancer 2 gene (BRCA2) are the two most-studied BC susceptibility genes. Genetic testing for disease-causing mutations in BRCA1, BRCA2, and other BC susceptibility genes is strongly recommended for members of families having a BC family history. The present study found a heterozygous c.5722_5723del mutation in the BRCA2 exon 11 of a large Han-Chinese BC family using whole exome sequencing and Sanger sequencing. It may cause DNA double-strand breaks repair dysfunction by disturbing homologous recombination, further resulting in BC. The study findings may help supplement and further improve genetic testing strategies and BC risk estimation methodologies in China.

A novel splice-site mutation in the ATP2C1 gene of a Chinese family with Hailey-Hailey disease

Hailey-Hailey disease (HHD), also known as familial benign chronic pemphigus, is an autosomal dominant genodermatosis. It is characterized by erosions, blisters and erythematous plaques at sites of friction or intertriginous areas. The pathogenic gene of HHD has been revealed as the ATPase secretory pathway Ca²⁺ transporting 1 gene ( ATP2C1), which encodes the protein, secretory pathway Ca ²⁺/Mn ²⁺-ATPase 1 (SPCA1). ATP2C1 gene mutations are responsible for HHD by resulting in abnormal Ca ²⁺ homeostasis in the skin and giving rise to acantholysis, a characteristic pathology of HHD. In this study, a four-generation family containing three HHD sufferers was recruited. Direct sequencing of the ATP2C1 gene was performed in the proband and other available family members. Reverse-transcriptase polymerase chain reaction analysis was conducted to show the potential variant effect on ATP2C1 splicing. A novel heterozygous c.325-2A>G transition at the splice acceptor site of intron 4 in the ATP2C1 gene was identified, and it co-segregated with the disease in this family. The mutation resulted in exon 5 skipping and an in-frame deletion of 12 amino acids (p.Ala109_Gln120del) in SPCA1. This splice-site mutation may be responsible for HHD in this family. This study would further expand the mutation spectrum of the ATP2C1 gene and may be helpful in the genetic counseling and prenatal diagnosis of HHD.