Compound heterozygosity for GDF5 in Du Pan type chondrodysplasia
AMERICAN JOURNAL OF MEDICAL GENETICS PART A
Authors: Douzgou, Sofia; Lehmann, Katarina; Mingarelli, Rita; Mundlos, Stefan; Dallapiccola, Bruno
Abstract
Du Pan type chondrodysplasia (DPC) represents the milder end of homozygous growth differentiation factor 5 (GDF5) disorders. We report on a 20-month-old child with complex brachydactyly and mild proximal fibular hypoplasia, consistent with DPC, in the absence of other anomalies of long bones and joints. Mutational analysis disclosed two novel GDF5 mutations within the protein's mature domain and in the clevage site of the prodomain which explains the district DPC phenotype found in this patient. The unaffected mother and the father who presented with mild brachybaso/mesophalangy of all digits were both heterozygous carriers. (C) 2008 Wiley-Liss, Inc.
Evolutionary Selection and Constraint on Human Knee Chondrocyte Regulation Impacts Osteoarthritis Risk
CELL
Authors: Richard, Daniel; Liu, Zun; Cao, Jiaxue; Kiapour, Ata M.; Willen, Jessica; Yarlagadda, Siddharth; Jagoda, Evelyn; Kolachalama, Vijaya B.; Sieker, Jakob T.; Chang, Gary H.; Muthuirulan, Pushpanathan; Young, Mariel; Masson, Anand; Konrad, Johannes; Hosseinzadeh, Shayan; Maridas, David E.; Rosen, Vicki; Krawetz, Roman; Roach, Neil; Capellini, Terence D.
Abstract
During human evolution, the knee adapted to the biomechanical demands of bipedalism by altering chondrocyte developmental programs. This adaptive process was likely not without deleterious consequences to health. Today, osteoarthritis occurs in 250 million people, with risk variants enriched in non-coding sequences near chondrocyte genes, loci that likely became optimized during knee evolution. We explore this relationship by epigenetically profiling joint chondrocytes, revealing ancient selection and recent constraint and drift on knee regulatory elements, which also overlap osteoarthritis variants that contribute to disease heritability by tending to modify constrained functional sequence. We propose a model whereby genetic violations to regulatory constraint, tolerated during knee development, lead to adult pathology. In support, we discover a causal enhancer variant (rs6060369) present in billions of people at a risk locus (GDF5-UQCC1), showing how it impacts mouse knee-shape and osteoarthritis. Overall, our methods link an evolutionarily novel aspect of human anatomy to its pathogenesis.