Molecular characterization of a novel translocation t(5;14)(q21;q32) in a patient with congenital abnormalities.

Chromosomal translocations are frequently found to be associated with various malignant disorders as well as congenital abnormalities. We report the characterization of a novel reciprocal translocation t(5;14)(q21;q32) in a patient with congenital abnormalities manifested by severe mental retardation, athetotic tetraplegia, microcephaly, peculiar facies (upward slanting of palpebral fissures), clinodactyly of the fifth fingers, and overlapping toes. Using a JHGP24 lymphoblast cell line derived from this patient, metaphase fluorescence in situ hybridization with bacterial artificial chromosome and cosmid probes and subsequent molecular analysis mapped the translocation breakpoint to the nucleotide level. Sequence analysis of the breakpoint junctions revealed the presence of a homologous sequence, GTGGC, along with a single nucleotide substitution and an insertion in der(14), and a single nucleotide deletion in the der(5) chromosome. We also attempted to identify and characterize the transcripts near the breakpoint by 5' and 3' rapid amplification of cDNA ends. Although we found several transcripts near the breakpoint of chromosome 14, the lack of significant ORFs within these transcripts suggests they are likely to be non-coding RNAs. These transcripts may have an important role in the neurogenesis or differentiation.