A rare case of mixed gonadal dysgenesis with mosaicism 45, X/46, X, +mar

INTRODUCTION: We present a rare patient case with mixed gonadal dysgenesis as a disorder of sex development (DSD) and a new pattern of chromosome in the karyotype, 45, X/46, X, +mar(Y). PRESENTATION OF CASE: A ten-year-old boy, raised in a nursery center, presented with ambiguous genitalia. Two cell lines, (45, X) and [46,X, +mar(Y)] were observed utilizing cytogenetic investigation including fluorescence in situ hybridization (FISH) which were carried out on his peripheral lymphocytes. A significantly higher percentage (75%) of Y-containing cells was observed in the blood, which could be considered the major reason why the case did not have distinct ambiguous genitalia. A further explorative laparoscopic procedure was performed, during which orchiectomy was performed, and remnants of Müllerian duct were excised. DISCUSSION: A complete and sufficiently careful medical evaluation and genetics counseling of neonates is highly recommended in order to avoid any delayed insufficient diagnostic, conservative, and therapeutic care in children living with guardians rather than their biological parents. Both molecular and cytogenetic studies are recommended in some DSDs to help early diagnosis of the disease, which is important for further essential surgical approaches. CONCLUSION: Cytogenetic studies followed by a laparoscopic exploratory and surgical survey are helpful tools for unraveling the mosaicism involving sex chromosomes and the complicated process in mixed gonadal dysgenesis patients.