Can Individuals with 47,XYY Karyotypes Exist without Male Phenotype? A Narrative Literature Review and Case Report.

Background: The 47,XYY syndrome is a genetic condition found in about 1 in 1000 male children. The expected phenotype is male but could vary greatly. Those with genitourinary abnormalities may also present with microphallus, hypoplastic scrotum, cryptorchidism, hypospadias and macroorchidism. This study reports a child with sex ambiguity who possesses an initial 47,XYY karyotype. We also conducted a narrative literature review of 47,XYY individuals and their respective genital phenotype and/or gender identity.

Methods: The narrative literature review was performed by searching for "47,XYY" in the PubMed database. All studies published in English, Spanish or Portuguese from January 1960 to January 2024 that contained the term "47,XYY" in the title or abstract were included. Studies that did not describe the genital phenotype and/or gender identity of cases were excluded. We also described the case of a 2-month-old patient with the 47,XYY karyotype and sex ambiguity.

Results: Our patient underwent additional karyotype testing, resulting in 47,XYY [30] and another 45,X [2]/47,XYY [98] with mosaicism being confirmed by fluorescent in situ hybridization (FISH) on buccal smears (nuc ish (DXZ1 × 1, DYZ3 × 2)[64/100]/(DXZ1 × 1, DYZ3 × 0)[36/100]. A gonadal biopsy revealed an atrophic testis on the left and a streak gonad on the right, with a final diagnosis of mixed gonadal dysgenesis determined. The narrative review revealed 643 articles, of which 350 met the inclusion criteria. However, we excluded 132 articles because they presented no new cases. We included 138 articles, which presented a series containing less than 10 new cases with the 47,XYY karyotype (total of 327 cases), 58 articles presented 4001 cases and 22 articles presented 75 patients with the 47,XYY karyotype in mosaic with 45,X. For all 4403 analyzed cases, 4354 (98.90%) presented a male phenotype, of which 4322 had the 47,XYY karyotype and 32 had mosaicism with 45,X lineage. A further 23 (0.52%) presented a female phenotype, of which four had the 47,XYY karyotype and 19 had mosaicism with 45,X lineage. In addition, 23 (0.52%) cases presented ambiguous genitalia, of which two had the 47,XYY karyotype and 21 had mosaicism with 45,X lineage. Finally, three (0.06%) cases had undefined phenotypes, all with mosaicism with 45,X lineage. Of the six cases with the 47,XYY karyotype and no male phenotype, one had complete androgen insensitivity syndrome (CAIS), one had lipoid congenital adrenal hyperplasia, two had probable CAIS, and two presented an incomplete diagnostic investigation.

Conclusions: A female or ambiguous genital phenotype in an individual with 47,XYY karyotype is uncommon and should alert to the presence of the 45,X lineage or association with other causes of disorder/difference of sex development.