SUN-028 Concomitant Mutations in the POR and AR Genes in a Boy Presenting with Micropenis and Premature Adrenarche

Abstract

Background: Micropenis is caused either by a defect in androgen synthesis, conversion to Dihydrotestosterone, or action due to mutant androgen receptor. Premature adrenarche is caused by excess of adrenal androgens.

Clinical case: A 6,5-year-old boy presented to our pediatric endocrinology clinic due to increased body weight and hyperthyreotropinemia. Physical examination revealed premature adrenarche with testicular volume 1,5 ml, micropenis (4cm, <-2 SDS) and acanthosis nigricans. His linear growth presented an acceleration the last 2 years from +0.85 to +1.81 SD and his bone age was advanced by 2 years with a statural height at -0.5 SD, not in accordance with the mean parental height (+0.90 SD). At the same time, his BMI was increased from +1,36 to +3,64 SDS.

Laboratory investigations for premature adrenarche with synacthen test revealed mild elevation of compound-S 15,4 ng/dl at 60’, which could be theoretically attributed to partial 11-β-hydroxylase deficiency (CYP11B1). DHEA was also elevated 2,1 ng/ml with an increased DHEA/Δ4 ratio at 20 (normal < 10) which could be explained in the case of partial 3-β-Hydroxysteroid dehydrogenase deficiency.

Method: Whole exome sequencing was preformed targeted to a gene panel related to premature adrenarche.

Results: A heterozygous mutation c.[1174C>T]+[1174C>T]; p.[Pro329Ser]+[Pro329Ser] in exon 1 in Androgen Receptor (AR) gene (X-linked) was found to the patient and his mother. The mutation, according to Human Gene Mutation Database, can cause disorder of sex development (DSD), partial androgen insensitivity syndrome (PAIS), infertility and hypospadias. Additionally, sequencing of the coding region of the P450 oxyreductase (POR) gene revealed a heterozygous mutation c.[642-5C>G] in exon 7, which in homozygosity can cause steroidogenesis disorder due to oxyreductase deficiency. This heterozygous POR mutation was found to the patient and his father.

Discussion: Our patient caries mutations in the AR and in POR genes. The AR mutation is obviously responsible for micropenis in our patient. CYP11B1 and 3β-Hydroxysteroid dehydrogenase genes were normal. POR deficiency is a disorder of steroidogenesis with phenotypic spectrum ranging from PCOS to ambiguous genitalia and glycocorticosteroid deficiency or even to classic Antley-Bixler syndrome (1).

Conclusion: The genetic and hormonal results in our case imply a role for POR in the CYP11B1 gene expression, which is reported for the first time to our knowledge.

1.

Concomitant Mutations in the P450 Oxidoreductase and Androgen Receptor Genes Presenting with 46,XY Disordered Sex Development and Androgenization at Adrenarche. J Clin Endocrinol Metab. 2010 Jul; 95(7): 3418-3427