Clinical and cytogenetic study of a case with familial chromosomal translocation presenting with facial dysmorphism and axial neuropathy

We report on a 9-year-old female patient presenting with muscle weakness, facial dysmorphism and mild mental retardation. She had low birth weight, developmental delay, hypotonia and hyporeflexia and difficulties in climbing the stairs. EMG revealed axonal polyneuropathy affecting both upper and lower limbs. She was the child of non-consanguineous parents, her cytogenetic findings revealed 46,XX,t(12;14)(q14;q23). The mother's karyotype was normal 46,XX while the father's karyotype was 46,XY,t(12;14)(q14;q23) the same as his daughter. Her normal sister's karyotype was also 46,XX,t(12; 14) (q14;q23). Fluorescence in situ hybridization (FISH) was used to elucidate the breakpoints and Array-CGH was done for the patient to confirm the balanced translocation. This observation is of interest because it represents a rare case of a balanced translocation with abnormal phenotype. Mutant genes causing axonal neuropathy have been located on various chromosomes other than 12q14 or 14q24. This report shows the importance of molecular cytogenetics and its correlation with abnormal phenotype and the possibility of another gene locus at the presently studied chromosomal breakpoints. Detailed correlations between chromosome aberrations and their phenotypes are of invaluable help in localising genes for axonal polyneuropathy.