Unbalanced X; autosome translocation

Unbalanced X; autosome translocation can result in multiple congenital abnormalities/mental retardation syndrome due to chromosomal imbalance. Here is described a patient with developmental delay, microcephaly, agenesis of corpus callosum, spasticity, seizures and dysmorphism as a result of meiotic malsegregation of balanced X; autosome translocation in mother. Present case signifies the importance of chromosomal analysis in a patient with developmental delay/ mental retardation and discuss lyonization in cases with X; autosome translocation.