Infantile glycerol kinase deficiency (GKD) is a severe form of GKD characterized clinically by poor feeding, failure to thrive, salt-wasting dehydration, vomiting, Addisonian pigmentation, hypotonia, and disorders of consciousness. Some patients have complex GKD associated with adrenal hypoplasia congenita and/or Duchenne muscular dystrophy (DMD) with manifestations including intellectual deficit, dysmorphic facial features, abnormal external genitalia, strabismus, seizures, and progressive lethargy. [ ]