Fetal Jacob Syndrome (47XYY): An Uncommon Association of Fetal Pulmonary Atresia with Ventricular Septal Defect

Jacob syndrome, also known as superman syndrome, is a sex chromosome aneuploidy characterized by an extra Y chromosome. The origin of this Y chromosome is paternal and results from nondisjunction in the second meiotic division (84% of cases) or a postfertilization mitotic error (16%). It does not result from increased parental age.1 Fetal Jacob syndrome does not have a specific phenotype although a few structural associations have been reported.1-3 Prenatal cases are usually picked up accidentally on cell free fetal DNA or karyotype/microarray offered for other indications.4 The case presented highlights an uncommon association of pulmonary atresia with ventricular septal defect with Jacob syndrome in a male fetus. The mechanism of an extra Y chromosome in causing this cardiac defect is unclear. PA-VSD is reported to be associated with 22q11.2 deletion syndrome in 25% cases.5 Association of PA-VSD with sex chromosomal abnormalities like Klinefelter syndrome (47XXY) has been reported but with Jacob syndrome (47XYY) is not yet reported.5 In this case, 22q11.2 deletion syndrome was ruled out by microarray (Fig. 2). In such cases, parents need to be counseled about the prognosis and in t r o D u c t i o n