MIXED GONADAL DYSGENESIS

Mixed gonadal dysgenesis (MGD) is an intersexual genetic abnormality caused by a defect in the sex chromosomes (gonosomes) associated with dysgenetic gonads and retained Müllerian structures. The most common gonosomal aberration in MGD is 45 X0/46 XY mosaic karyotype. The external genitalia could be normal looking female and these children will present later in life with primary amenorrhea. Otherwise, it could be ambiguous: clitoromegaly and urogenital sinus to a sizable phallus with hypospadia. A uterus and one or both fallopian tubes may also be present. MGD is characterized by a streak gonad and a contralateral testis (that is typically cryptorchid) or bilateral streak testes. The testis might show prepubertal tubules lined by a few spermatogonia and immature Sertoli cells. Female gender assignment is usually preferred, but male assignment is an alternative in instances of extreme virilization. Dysgenetic gonads with the presence of a Y chromosome or a translocated fragment have a significant risk of developing malignant gonadoblastoma (though seminoma and dysgerminoma can occur). Routine early bilateral gonadectomy is advice in MGD. The child to be raised as a female will need clitoral recession and vaginoplasty in early infancy. If it is to be raised as male, then various types of hypospadias repair can be done, gonads can be replaced with prostheses, the prepenile scrotum reconstructed and Müllerian structures removed.