Many organ systems are affected by<unk> y, but the central nervous system and skeleton are the most severely affected: Common central nervous system defects seen in<unk> y include holoprosencephaly, hydrocephalus (increased amount of cerebrospinal fluid within the brain), ventriculomegaly, Arnold–Chiari malformation, agenesis of the corpus callosum and neural tube defects. Skeletal manifestations include cleft lip/palate, hypertelorism, club foot and syndactyly of fingers three and four. Congenital heart defects, hydronephrosis, omphalocele and meningocele (spina bifida) are also common. Cystic hygromas occur but are uncommon.<unk>  fetuses have intrauterine growth restriction beginning early in the pregnancy, as early as 12 weeks, and does not affect the head as severely as the body. Oligohydramnios, low levels of amniotic fluid, is common in<unk>  pregnancies. Placental abnormalities are common in<unk> y. Most frequently, the placenta is enlarged and may have cysts within. In some cases, the placenta may be unusually small, having ceased to grow. During the first trimester, fetuses with<unk> y have a thicker fluid under the skin behind their neck, which calls for observation during the first and second trimester of gestation. The mother will usually have high levels of specific proteins including maternal serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (hCG). Symptoms to look out for include but are not limited to swelling, edema, or hypertension. Infants may show facial abnormalities, micrognathia, cleft lip, spina bifida, as well as other birth defects that result from kidney, limb, and umbilical cord complications. They are also prone to being smaller than a normal sized newborn, a problem that arises while the infant is still a fetus.
Triploid syndrome
XX male syndrome
XXXY syndrome
XXXXY syndrome
Microdeletion syndrome
Chromosome instability syndrome
XXYY syndrome
XYY syndrome