Complex chromosome rearrangement 46,XY,t(10;14)(q11.22;q12),inv(10)(q11.22;q24.2) in a neurodevelopmentally delayed boy. : Does disruption of Striatin-3 (STRN3) cause the phenotype?

Abstract

Mental retardation occurs in 2-3% of newborns in the population and can be inherited from the parents, caused by environmental influences or de novo mutations. Microscopically visible chromosome aberrations, such as trisomy 21, are found in one out of seven individuals with severe mental retardation. As the resolution of microscopic techniques have improved, and methods such as fluorescent in situ hybridization (FISH) and array comparative genomic hybridization (aCGH) have been introduced, many submicroscopic rearrangements have been discovered in these patients. The aim of this study was to perform a detailed chromosome analysis of a patient with unexplained mental retardation and characterize chromosome abnormalities that might explain the phenotype. The patient has corpus callosum agenesia, microcephaly and enlarged ventricles of the brain and is the second child of two healthy parents. The patient’s DNA was analyzed by G-banding, FISH, aCGH, real time PCR and long range PCR which discovered an apparently balanced de novo translocation between chromosome 10 and 14 including an inversion on chromosome 10. Three copy number variations were detected by aCGH, a duplication on chromosome X and a deletion on chromosome 7 and 3, where the first two were inherited from the mother. The breakpoints of the translocation and inversion showed a possible disruption of the genes STRN3 and C10orf28 which have shown to be expressed in brain and placenta, respectively. Further analysis of the function of the genes and the exact breakpoint positions could determine the cause mental retardation in this patient.