Brachydactyly mental retardation syndrome in differential diagnosis of pseudopseudohypoparathyroidism

Abstract

Patients with Albright hereditary osteodystrophy (AHO) phenotype are usually seen in pediatric endocrinology policlinics when they are evaluated for short stature and/or obesity. Brachydactyly mental retardation syndrome (BDMR, OMIM #600430) is a rare genetic disorder caused by aberrations of chromosomal region 2q37 and characterized with AHO-like phenotype without any hormone resistance. Diagnosis of BDMR is based on the detection of the deletion on the long arm of chromosome 2. Diagnosis can usually be made with karyotype analysis but sometimes chromosomal deletion can only be detected by fluorescent in situ hybridization (FISH) screening. We report a patient with the AHO phenotype whose karyotype was normal but who was diagnosed with BDMR with FISH analysis showing 2q deletion. In pediatric endocrinology practice, in patients with AHO phenotype but without parathormone (PTH) resistance, BDMR should be considered. For the diagnosis of BDMR, the subtelomeric region of chromosome 2 should be screened for deletion by FISH analysis even in patients with normal karyotypes.