A familial interstitial 4q35 deletion with no discernible clinical effects

Small deletions on the long arm of distal chromosome 4 do not appear to result in gross congenital malformations, with the most frequently reported clinical findings including mild to moderate intellectual disability, learning disabilities and minor dysmorphic features. Here we report on a cytogenetically detectable familial interstitial chromosome 4 long arm deletion with no discernible phenotypic effects in a mother and her two daughters. The karyotypes of the mother and her two daughters were: 46,XX,del(4)(q35.1q35.2). Based on the results of FISH analyses using whole chromosome specific and subtelomeric probes, the karyotype was designated as: 46,XX,del(4)(q35.1q35.2). ish del(4)(q35-qter)(WCP4+, 36P21+, dJ963K6-). Array-CGH analysis showed an interstitial deletion encompassing 5.75 Mb in the 4q35.1-q35.2 genomic region (chr4:184,717,878-190,469,337; hg19). This is the first report on a cytogenetically detectable familial interstitial chromosome 4 long arm deletion in which there are no discernible phenotypic effects. Both our findings and a review of the literature suggest that more detailed molecular analyses are needed in cases with distal chromosome 4 long arm deletions especially those with breakpoints in the 4q35 region to establish a more precise genotype-phenotype correlation.