Maternal uniparental disomy for chromosome 6 in a patient with IUGR, ambiguous genitalia, and persistent mullerian structures.

Maternal uniparental disomy of chromosome 6 [upd(6)mat] is rare and has only been previously reported 13 times with the main associated phenotype being IUGR. We present a case of a male patient with isodisomy upd(6)mat resulting in severe IUGR and ambiguous genitalia, a phenotype not previously described in association with this chromosome finding. The patient initially presented prenatally with IUGR at 19 weeks gestation with placental dysfunction and ambiguous genitalia noted at 27 weeks. Postnatally, the patient had external genital abnormalities, the gonads were in the inguinal canal and there was a rudimentary appearing vagina and uterus. Karyotype is 46, XY and SNP array revealed maternal isodisomy of 171 Mb at 6p25.3q27 with no pathogenic copy number variants. To our best knowledge, this is the first case of an XY patient with upd(6)mat with IUGR and ambiguous genitalia, further supporting previous reports regarding an association between upd(6)mat and IUGR. This patient also presented with a disorder of sex development (46, XY DSD) with the sex chromosome being male and positive for the SRY gene, testicular gonadal sex and abnormal external and internal genitalia.