We present a case of an interstitial subtelomeric 10q26 deletion in a male child with moderate developmental delay and minor dysmorphic features. Using array comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH), we have detected an interstitial deletion at 10q26.2q26.3 encompassing a 5.8？Mb region and spanning 24 genes. Interestingly, losses of this chromosome 10 region have not been previously associated with a phenotype outcome. According to an in silico evaluation, we have suggested that PPP2R2D and BNIP3 losses are likely a cause of developmental delay in the index patient. Our data allow to speculating that haploinsufficiency of these two genes in 10q26.3, which is usually ignored in the context of chromosome 10q deletions, has a phenotypic effect. 1. Introduction Although subtelomeric chromosomal rearrangements are common in children with intellectual disability, developmental delays and/or dysmorphic features [1–3], deletions affecting subtelomere of chromosome 10 long arm, are rare [4]. This probably explains the small amount of such cases addressed by array comparative genomic hybridization (CGH) [4, 5] in contrast to the number of reports on phenotypic manifestations of chromosome 10q25q26/10q26qter loss analyzed using molecular cytogenetic techniques with a lower resolution [6–8]. Here, we report a case of an interstitial 10q26 deletion in a male child presenting with a phenotypic outcome atypical for subtelomeric deletions at 10qter detected by array CGH and confirmed by fluorescence in situ hybridization (FISH). 2. Case Presentation and Methods 2.1. Clinical Description A 28-month-old male child with moderate developmental delay and minor dysmorphic features has been referred to (molecular) cytogenetic analysis. The patient was born at 37 weeks of gestation to a 20-year-old mother and 21-year-old father by spontaneous vaginal delivery with a birth weight of 3.16？kg (~25th percentile) and length of 52.6？cm (~75th percentile). Pregnancy history was unremarkable. At 6 months of age, he was able to roll over and sit with support. Physical examination at the age of 2 years and 4 months showed dysmorphic features (flat feet with cutaneous syndactyly of the second and third toes; high forehead and prominent auricles) without any other remarkable congenital malformations and dysmorphic features. A moderate developmental delay was noticed. 2.2. Cytogenetic Analysis GTG-banding was done according to standard procedures analyzing 30 metaphase plates at a resolution of 550 bands. Karyotype abnormalities were not
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