A case report of concomitant myopathy, adrenal insufficiency, and mental retardation linked with deletion of Xp21

Abstract

Contiguous gene syndromes (CGS) are the disorders caused by chromosomal abnormalities: Deletions, duplications, or other complex rearrangements that alter gene dosage. Initially, before their chromosomal nature is elucidated, they may be misdiagnosed as monogenic disorders depending on the leading clinical symptom cluster. The altered chromosomal region in individuals with this condition is typically less than 5 Mb in size and sometimes cannot be identified by conventional karyotyping. Patients present with signs of the diseases associated with each individual monogenic disorder. The Xp21-linked genetic syndrome, or glycerol kinase deficiency (GKD) (MIM 300474), is an example of this syndrome [1-3]. The genes coding for glycerol kinase (GK), congenital adrenal hypoplasia (NR0B1), and dystrophin (DMD) follow each other in the Xp21.2-p21.3 region. Deletions of an X-chromosome region may cause several monogenic disorders in one patient, including primary adrenal insufficiency and hypogonadotropic hypogonadism as a result of deletion in the NR0B1 gene, Duchenne muscular dystrophy (or a milder form, Becker muscular dystrophy) resulting from deletion in the dystrophin gene, and mental retardation as a result of deletion in the glycerol kinase gene. We report a case of concomitant myopathy, adrenal insufficiency, and mental retardation linked with deletion of Xp21.