A novel nonsense mutation in HSD17B3 gene in a Tunisian patient with sexual ambiguity.

INTRODUCTION: 17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) isoenzyme is present almost exclusively in the testes and converts delta 4 androstenedione to testosterone. Mutations in the HSD17B3 gene cause HSD17B3 deficiency and result in 46,XY Disorders of Sex Development (46,XY DSD).

AIM: This study aimed to present the clinical and biochemical features of a Tunisian patient who presented a sexual ambiguity orienting to HSD17B3 deficiency and to search for a mutation in the HSD17B3 gene by DNA sequencing.

METHODS: Polymerase chain reaction (PCR) amplification and subsequent sequencing of all the coding exons of HSD17B3 gene were performed on genomic DNA from the patient, her family, and 50 controls.

RESULTS: Genetic mutation analysis of the HSD17B3 gene revealed the presence of a novel homozygous nonsense mutation in the exon 9 (c.618 C>A) leading to the substitution p.C206X. The mutation p.C206X in the coding exons supports the hypothesis of HSD17B3 deficiency in our patient.

CONCLUSION: The patient described in this study represented a new case of a rare form of 46,XY DSD, associated to a novel gene mutation of HSD17B3 gene. The screening of this mutation is useful for confirming the diagnosis of HSD17B3 deficiency and for prenatal diagnosis.