A novel 5p15.33-14.1 deletion and 4q34.24-35.2 duplication in a patient with mental retardation, dysmorphic features and severe speech delay.

Abstract

A male patient with microcephaly, severe mental retardation and speech delay, and dysmorphic features such as hypertelorism and micromandible was reported. The karyotype of the patient was determined to be 46,XY,der(5)t(4;5)(q34.2;p14.1) through high-resolution karyotype analysis and fluorescence in situ hybridization (FISH) detection. The patient’s mother and elder sister were both translocation carriers involving 4q34.2 and 5p14.1. A 25 Mb deletion of 5p15.33-14.1 and a 13 Mb duplication of 4q34.2-35.2 were revealed by the copy number variation analysis of the whole genome in this patient. This is the first report of a case with copy number variation involving 5p15.33-14.1 and 4q34.2-35.2. The incidence of mental retardation is about 1–3% (Chelly et al. 2006) worldwide. Among the aetiologies that cause mental retardation it would appear that 30% have a genetic origin (Rodriguez-Revenga Bodi et al. 2006). Various chromosome deletions, duplications and rearrangements can lead to mental retardation of different extent (Chelly et al. 2006). The 5p deletion syndrome is one of the most common causes of mental retardation. However, some cases are caused by the unequal segregation of a parental balanced translocation where the 5p monosomy is accompanied by a trisomy of the terminal segment of the other chromosomal arm (Mutchinick et al. 1988; Vasudevan and Parker 2006; Hellani et al. 2010). In this paper, we report a case with microcephaly, severe mental retardation and speech delay, and dysmorphic features. A balanced reciprocal translocation between 4q and 5p was present in his mother and elder sister. The karyotype of the patient thus was 46,XY,der(5)t(4;5)(q34.2;p14.1), and partial monosomy 5p