Introduction: Partial androgen insensitivity syndrome is a rare X-linked 46, XY disorder caused by androgen receptor dysfunction, producing variable genital ambiguity and complex diagnostic challenges in early infancy and childhood. Case: We report a term infant, currently aged 9 months, who was admitted to the Neonatal Intensive Care Unit at birth for glucose-6-phosphate dehydrogenase (G6PD) deficiency and noted to have ambiguous genitalia. The infant had no hypoglycemia, feeding intolerance, or electrolyte disturbances throughout admission. She is the second child of non-consanguineous parents, with no family history of disorders of sex development. Examination of the external genitalia revealed a prominent phallus without erectile tissue with mildly pigmented and rugated labioscrotal folds. There was no labioscrotal fusion. Bilateral gonads were palpable in both labioscrotal folds with one opening seen. Pelvic ultrasonography showed bilateral small testes within the labioscrotal folds, with absence of Müllerian structures. Karyotype analysis confirmed 46, XY genotype. Human chorionic gonadotropin stimulation (HCG) testing at day 7 of life demonstrated normal baseline testosterone 4.9 nmol/L, but minimal testosterone rise 5.4 nmol/L at day 4 post HCG. Normal testosterone to dihydrotestosterone ratio and testosterone to androstenedione ratio excluded defects in androgen synthesis, while normal adrenal steroid profile ruled out congenital adrenal hyperplasia. Gonadotropin-releasing hormone stimulation at 2 months old revealed a peak follicle-stimulating hormone of 8 IU/L and peak LH of 4 IU/L. Anti-Müllerian hormone level was markedly elevated >328 pmol/L (normal 5.5–103 pmol/L). Whole-exome sequencing identified a hemizygous androgen receptor gene variant, p.(Pro818Ala), classified as a variant of uncertain significance with deleterious in silico predictions, consistent with X-linked partial androgen insensitivity syndrome. Conclusion This case highlights the necessity of early, systematic endocrine evaluation integrated with genomic testing in 46, XY DSD to achieve a definitive diagnosis, optimize sex assignment, and guide longitudinal, multidisciplinary management.
Male ; Infant ; Androgen-Insensitivity Syndrome