A neonate with contiguous deletion syndrome in XP21

Abstract

We report a case of a male infant with the association of pseudohypertriglyceridemia, hypoadrenalism (hyponatremia, hyperpotasemia, dehydration), high creatine phosphokinase level (possible Duchenne's muscular dystrophy, DMD) and diagnosed contiguous gene deletion syndrome in Xp21. A 1-month-old male term infant was referred due to no weight gain. The examination revealed dehydration (decreased skin turgor), scrotal hyperpigmentation and hypotonia. Laboratory findings showed hyponatremia of 124 mmol/L, hyperpotasemia of 6.9 mg/dL, high creatine phosphokinase level of 7019 IU/L, and high blood triglyceride level of 1244 mg/dL. There was no deletion detected in the dystrophin gene with the study investigating selected exons, no dystrophin staining and nonspecific atrophic findings in the muscle biopsy. Further laboratory findings defined high glycerol concentrations both in blood and in urine that were compatible with a glycerol kinase deficiency (GKD). Array CGH study confirmed the existence of a deletion in Xp21 of the genes responsible for DMD, GKD and the congenital adrenal hypoplasia (gene DAX1 or NROB1 gene: Xp21.3-21.2). The infant showed good response to mineralocorticoid therapy, hyponatremia resolved and gained weight. Physicians should consider contiguous gene deletion syndrome in Xp21 in the infants with myopathic compromise, increased levels of creatine phosphokinase and pseudohypertriglyceridaemia to be able to prevent and treat the metabolic complications. Furthermore, geneticists should take into account to design routine deletion studies including the promoter region in this disorder.