Molecular genetic analysis of a de novo balanced translocation t(6;17)(p21.31;q11.2) associated with hypospadias and anorectal malformation

Abstract

We report a young boy with penoscrotal hypospadias, anal atresia (AA) with a recto-urethral fistula, a hypoplastic kidney and a balanced translocation t(6;17)(p21.31;q11.2). Physical mapping of the breakpoints localized the chromosome 6 breakpoint within an intron of the gene lipoma HMGIC fusion partner-like 5 (LHFPL5) whereas the chromosome 17 breakpoint was mapped to the first intron of the 182-FIP gene encoding the Fragile X Mental Retardation Protein Interacting Protein. Sequence analysis across the breakpoints revealed an almost perfectly balanced translocation with a 2 bp deletion on the derivative chromosome 6 and a 7 bp duplication on the derivative chromosome 17. We identified a fusion transcript consisting of the first exon of 182-FIP and the last exon of LHFPL5 in patient-derived cells. Quantitative expression analysis of the genes flanking the breakpoints, revealed increased transcript levels for SFRS protein kinase 1 (SRPK1) and TAO kinase 1 (TAOK1) which suggests a positional effect due to the translocation. We hypothesize that the urogenital and anorectal malformations in the patient result from one or several mechanisms including disruption of the genes 182-FIP and LHFPL5, altered expression of the genes flanking the translocation breakpoints and, a gain of function mechanism mediated by the 182-FIP-LHFPL5 fusion transcript.