<unk> y may be suggested by dramatically elevated levels of serum alpha-fetoprotein. On obstetric ultrasonography, abnormalities of the skeleton, central nervous system, heart, abdomen, and kidneys are visible in the most severe cases beginning at 12-14 weeks of pregnancy. Placental abnormalities associated with a<unk>  pregnancy become visible at 12-14 weeks. Placentomegaly or intrauterine growth restriction are the typical findings that prompt evaluation for<unk> y, though oligohydramnios may be the first sign in some cases. Placentomegaly is not pathognomonic for<unk> y because in some cases, the placenta senesces.<unk> y must be distinguished from trisomy 13 and trisomy 18, which may appear similar on sonography. Genetic testing allows for a definitive diagnosis. A sample of amniotic fluid can also be tested to diagnose<unk> y.
Triploid syndrome
XX male syndrome
XXXY syndrome
XXXXY syndrome
Microdeletion syndrome
Chromosome instability syndrome
XXYY syndrome
XYY syndrome