A cryptic microdeletion including MBD5 occurring within the breakpoint of a reciprocal translocation between chromosomes 2 and 5 in a patient with developmental delay and obesity.

The 2q23.1 deletion syndrome has been recently recognized as a neurodevelopmental disorder associated with intellectual disability, epilepsy, and autism spectrum disorder. Recently, methyl-CpG-binding domain 5 gene (MBD5), located in the 2q23.1 region, has been considered as a single causative gene of this syndrome. We report on a female patient with a de novo reciprocal translocation between chromosomes 2 and 5. Chromosomal microarray testing revealed a cryptic 896 kb deletion that included MBD5. Although clinical manifestations of this patient are compatible with those of patients with 2q23.1 deletion syndrome, a focal pachygyria revealed by brain magnetic resonance imaging has never been observed in the previously reported cases. Obesity caused by hyperphagia was observed in our patient and 28% of the previously reported patients with the 2q23.1 deletion syndrome. For better medical management, appropriate dietary guidance against hyperphagia should be given to the patients' family.