Parkinson's disease (PD) is a genetically heterogeneous neurodegenerative disease with poorly defined environmental influences. Genomic studies of PD patients have identified disease-relevant monogeni Show more
Parkinson's disease (PD) is a genetically heterogeneous neurodegenerative disease with poorly defined environmental influences. Genomic studies of PD patients have identified disease-relevant monogenic genes, rare variants of significance, and polygenic risk-associated variants. In this study, whole genome sequencing data from 90 young onset Parkinson's disease (YOPD) individuals are analyzed for both monogenic and polygenic risk. The genetic variant analysis identifies pathogenic/likely pathogenic variants in eight of the 90 individuals (8.8%). It includes large homozygous coding exon deletions in PRKN and SNV/InDels in VPS13C, PLA2G6, PINK1, SYNJ1, and GCH1. Eleven rare heterozygous GBA coding variants are also identified in 13 (14.4%) individuals. In 34 (56.6%) individuals, one or more variants of uncertain significance (VUS) in PD/PD-relevant genes are observed. Though YOPD patients with a prioritized pathogenic variant show a low polygenic risk score (PRS), patients with prioritized VUS or no significant rare variants show an increased PRS odds ratio for PD. This study suggests that both significant rare variants and polygenic risk from common variants together may contribute to the genesis of PD. Further validation using a larger cohort of patients will confirm the interplay between monogenic and polygenic variants and their use in routine genetic PD diagnosis and risk assessment. Show less
Dyggve-Melchior-Clausen (DMC) syndrome was described in 1962 as an autosomal recessive type of spondyloepimetaphyseal dysplasia associated with mental retardation. Dymeclin (DYM) gene on chromosome 18 Show more
Dyggve-Melchior-Clausen (DMC) syndrome was described in 1962 as an autosomal recessive type of spondyloepimetaphyseal dysplasia associated with mental retardation. Dymeclin (DYM) gene on chromosome 18q12.1 that encodes for DYM protein which is expressed in cartilage, bone, and brain is mutated in DMC. A 6 year -old male child presented with bilateral gradually progressive genu varum deformity of 4 years' duration. There was no significant past medical and family history. A plain radiograph of his knee, pelvis, and spine shows some classical signs of skeletal dysplasia. A plain radiograph of the pelvis with both hips shows a classical semilunar, irregular lacy appearance around the iliac crest which is a pathognomonic radiological sign of this syndrome. The radiographic lacy appearance of iliac crests and generalized platyspondyly with double-humped end plates are pathognomonic of DMC. Show less