Copy number variants in patients with short stature
EUROPEAN JOURNAL OF HUMAN GENETICS
Authors: van Duyvenvoorde, Hermine A.; Lui, Julian C.; Kant, Sarina G.; Oostdijk, Wilma; Gijsbers, Antoinet C. J.; Hoffer, Mariette J. V.; Karperien, Marcel; Walenkamp, Marie J. E.; Noordam, Cees; Voorhoeve, Paul G.; Mericq, Veronica; Pereira, Alberto M.; Claahsen-van de Grinten, Hedi L.; van Gool, Sandy A.; Breuning, Martijn H.; Losekoot, Monique; Baron, Jeffrey; Ruivenkamp, Claudia A. L.; Wit, Jan M.
Abstract
Height is a highly heritable and classic polygenic trait. Recent genome-wide association studies (GWAS) have revealed that at least 180 genetic variants influence adult height. However, these variants explain only about 10% of the phenotypic variation in height. Genetic analysis of short individuals can lead to the discovery of novel rare gene defects with a large effect on growth. In an effort to identify novel genes associated with short stature, genome-wide analysis for copy number variants (CNVs), using single-nucleotide polymorphism arrays, in 162 patients (149 families) with short stature was performed. Segregation analysis was performed if possible, and genes in CNVs were compared with information from GWAS, gene expression in rodents' growth plates and published information. CNVs were detected in 40 families. In six families, a known cause of short stature was found (SHOX deletion or duplication, IGF1R deletion), in two combined with a de novo potentially pathogenic CNV. Thirty-three families had one or more potentially pathogenic CNVs (n = 40). In 24 of these families, segregation analysis could be performed, identifying three de novo CNVs and nine CNVs segregating with short stature. Four were located near loci associated with height in GWAS (ADAMTS17, TULP4, PRKG2/BMP3 and PAPPA). Besides six CNVs known to be causative for short stature, 40 CNVs with possible pathogenicity were identified. Segregation studies and bioinformatics analysis suggested various potential candidate genes. published online 25 September 2013
Phenotypic variability in a Hungarian patient with the 4q21 microdeletion syndrome
MOLECULAR CYTOGENETICS
Authors: Komlosi, Katalin; Duga, Balazs; Hadzsiev, Kinga; Czako, Marta; Kosztolanyi, Gyoergy; Fogarasi, Andras; Melegh, Bela
Abstract
Background: Interstitial deletions of 4q21 (MIM 613509) have already been reported in more than a dozen patients with deletions ranging from 2 to 15.1 Mb delineating a common phenotype including marked growth restriction, hypotonia, severe developmental delay with absent or delayed speech and distinctive facial features. A minimal critical region of 1.37 Mb accounting for the common features with 5 known genes (PRKG2, RASGEF1B, HNRNPD, HNRPDL, and ENOPH1) has been described so far. Results: Here we report on a 5 year-old Hungarian girl presenting with severe developmental delay, good receptive language but absent spoken speech, short stature, dystrophy, hypotonia, distinctive facies including broad forehead, frontal bossing, downward slanting palpebral fissures, hypertelorism, hypoplastic ear-lobes, anteverted nostrils, short philtrum, small mouth, higharched palate, short, small hands and feet, distally narrowing fingers and clinodactyly. Cerebral MRI showed ventricular dilation and an increase in periventricular signal intensity. After extensive metabolic tests and exclusion of subtelomeric deletions array CGH analysis was performed using the Agilent Human Genome G3 SurePrint 8x60K Microarray (Agilent Technologies, USA), which detected a 4,85 Mb de novo interstitial deletion of 4q21.21-4q21.23. The clinical symptoms only partly overlap with reported 4q21 microdeletion cases. Among multiple annotated genes our patient is also haploinsufficient for the following genes: RASGEF1B being a strong candidate for the neurodevelopmental features and PRKG2 for severe growth delay. Conclusion: The first Hungarian case of 4q21 deletion adds to the phenotypic spectrum of this novel microdeletion syndrome and underlines the importance of array CGH to uncover the heterogeneous causes of intellectual disability.