J Clin Res Pediatr Endocrinol. 2016; 8(3): 356-359 | DOI: 10.4274/jcrpe.2824

Corticosterone Methyl Oxidase Deficiency Type 1 with Normokalemia in an Infant

Ala Üstyol¹, Mehmet Emre Atabek¹, Norman Taylor², Matthew Chun-wing Yeung³, Angel O. K. Chan^3
1Necmettin Erbakan University Faculty Of Medicine, Department Of Pediatric Endocrinology And Diabetes, Konya, Turkey
²King’S College Hospital, Clinic Of Clinical Biochemistry, London, United Kingdom
³The University Of Hong Kong, Queen Mary Hospital, Clinic Of Pathology, Pokfulam, Hong Kong

Isolated aldosterone synthase deficiency may result in life-threatening salt-wasting and failure to thrive. The condition involves hyperkalemia accompanying hyponatremia. Two types of aldosterone synthase deficiency may be observed depending on hormone levels: corticosterone methyl oxidase type 1 (CMO 1) and CMO 2. Herein, we describe a Turkish infant patient with aldosterone synthase deficiency who presented with failure to thrive and salt wasting but with normal potassium levels. Urinary steroid characteristics were compatible with CMO I deficiency. Diagnosis of aldosterone synthase deficiency was confirmed by mutational analysis of the CYP11B2 gene which identified the patient as homozygous for two mutations: c.788T>A (p.Ile263Asn) and c.1157T>C (p.Val386Ala). Family genetic study revealed that the mother was heterozygous for c.788T>A and homozygous for c.1157T>C and the father was heterozygous for both c.788T>A and c.1157T>C. To the best of our knowledge, this is only the second Turkish case with a confirmed molecular basis of type 1 aldosterone synthase deficiency. This case is also significant in showing that spot urinary steroid analysis can assist with the diagnosis and that hyperkalemia is not necessarily part of the disease.

Keywords: Corticosterone methyl oxidase,salt wasting,CYP11B2 gene,failure to thrive

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