Endocrine Abstracts

Introduction: Thomsen’s disease is a non-dystrophic congenital myotonia with autosomal dominant inheritance. Its association with short stature attributed to growth hormone deficiency (GHD) has never been reported in literature to our best knowledge.

Case report: A 14-years-old Moroccan boy, with no particular medical history, presented for evaluation of a short stature. On physical examination, the patient had a height of 141 cm (−2.5 S.D. on presumed growth curve) and a weight of 33 kg (−3 S.D.). His bone age was estimated at 10 years (4-year differential with chronological age). The etiologic assessment concluded to an isolated GHD. In addition, the patient has an ‘athletic’ appearance with a stiffness of the abdominal muscles, increased by cold. The family history revealed the presence of a similar family case (the maternal uncle). Electromyography showed typical mytonic bursts. All these typical features pointed to the diagnosis of Thomsen’s disease. In concert with neurologists, the patient was treated with carbamazepine (200 mg×2/day) and growth hormone (0.035 mg/kg/day). The follow-up noticed an improvement of the neurological symptomatology and a weight gain of 3 cm after 3 months of treatment.

Discussion: Thomsen myotonia belongs to the broad group of muscle channelopathies, caused by mutations in the chloride channel gene (CLCN1), which is located on chromosome 7. Its association with GHD suggests the presence of intricate biomolecular factors. A mutation in the growth hormone-releasing hormone receptor gene (GHRHR), located on the same chromosome, seems a plausible hypothesis to explain this association.