Abstract
We report two unrelated patients with overlapping chromosome 2q13 deletions (patient 1 in chr2:111415137-113194067 bp and patient 2 in chr2:110980342-113007823 bp, hg 19). Patient 1 presents with developmental delay, microcephaly and mild dysmorphic facial features, and patient 2 with autism spectrum disorder, borderline cognitive abilities, deficits in attention and executive functions and mild dysmorphic facial features. The mother and maternal grandmother of patient 1 were healthy carriers of the deletion. Previously, 2q13 deletions were reported in 27 patients, and the interpretation of its clinical significance varied. Our findings support that the 2q13 deletion is associated with a developmental delay syndrome manifesting with variable expressivity and reduced penetrance which poses a challenge for genetic counselling as well as the clinical recognition of 2q13 deletion patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13039-015-0157-0) contains supplementary material, which is available to authorized users.
Highlights
Genome-wide analyses performed on large numbers of patients have led to the discovery of a multitude of copynumber variations (CNVs)
For example the chromosome 1q21.1 deletion is found in patients manifesting one of several features including intellectual disability (ID), autism spectrum disorders (ASDs), schizophrenia, microcephaly, cataracts and congenital heart defects, and it is detected in healthy carriers [3, 4]
Samples were sexmatched with Human Genomic DNA (Promega, Madison, WI). Array Comparative Genome Hybridization (aCGH) slides were scanned with the Agilent Microarray Scanner, data obtained using Feature Extraction software (v. 6.1.1) and visualized by Agilent Workbench (v. 3.5.14)
Summary
Genome-wide analyses performed on large numbers of patients have led to the discovery of a multitude of copynumber variations (CNVs). Segmental duplications predispose genomic regions to recurrent duplication and deletion by non-allelic homologous recombination (NAHR) events, some of which cause clinically recognizable core phenotypes, e.g., Angelman, Prader-Willi, Smith-Magenis and Williams-Beuren syndromes (reviewed by [1]). Other imbalances, such as deletions in chromosome 1q21, 15q11, 15q13 and 16p11, present with significant clinical variability [2]. The patients present with an apparently unspecific and variable clinical phenotype, including developmental delay (DD), ASDs, attention deficits hyperactivity disorder (ADHD), heart defects and craniofacial abnormalities, and several healthy carriers have been identified [8, 9, 11, 15]. The clinical significance of the 2q13 deletion is not fully determined
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