Next-generation DNA sequencing in an appropriate sex assignment: case report of two phenotypically similar patients with 46, XY disorder of sex development

Background: Disorders of sex development (DSD) are known as the inborn atypical development of chromosomal, gonadal, or anatomic sex. New opportunities in counseling DSD patients have emerged with advent of the next generation DNA sequencing (NGS) techniques. Case Presentation: Two clinical 46, XY DSD cases having similar phenotypical features, including ambiguous genitalia, are presented in this paper. In the first patient, no causative variant was found, meanwhile, a heterozygous variant in the CHD 7 gene considered as likely-benign was identified (chr8: 61693942, rs377139749, NM_017780.3:c.2053_2058dupGCAAAA p.Lys686_Thr687insAlaLys). Neither gonadal ability to produce androgens, nor tissue androgen sensitivity was impaired, therefore leading to a decision to maintain the initially assigned male sex in this patient. In the other patient, the study revealed previously reported heterozygous missense variant in the SEMA3A gene (chr7: 83636785, rs769957117, NM_006080.2:cA1024G:p. Met342Val) responsible for HH type 16 (OMIM 614897). As well, a novel hemizygous variant in the AR gene (chrX: 66942818, AR: NM_000044:c.G2599C:pVal867Leu) was identified. In conjunction with the features of HH, this leads to a decision to reassign the sex of rearing to a female. Conclusion: NGS technique may be helpful in optimal sex assignment in DSD cases.