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Many organ systems are affected by triploidy, but the central nervous system and skeleton are the most severely affected: . Common central nervous system defects seen in triploidy include holoprosencephaly, hydrocephalus (increased amount of cerebrospinal fluid within the brain), ventriculomegaly, Arnold–Chiari malformation, agenesis of the corpus callosum and neural tube defects.
The CDC and National Birth Defect Project studied the incidence of birth defects in the US. Key findings include: [ citation needed ] Down syndrome was the most common condition with an estimated prevalence of 14.47 per 10,000 live births, implying about 6,000 diagnoses each year.
The twin reversed arterial perfusion, or T.R.A.P. sequence, results in an 'acardiac twin', a parasitic twin that fails to develop a head, arms and a heart.The parasitic twin, little more than a torso with or without legs, receives its blood supply from the host twin by means of an umbilical cord-like structure, much like a fetus in fetu, except the acardiac twin is outside the autosite's body.
The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child.
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Spina bifida (SB; /ˌspaɪnə ˈbɪfɪdə/, [9] Latin for 'split spine') [10] is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. [1]
Conjoined twinning is one of the oldest known birth defects in history and examples with human's fascination with twins is extremely evident throughout historical literature. Although there are cases of conjoined twins dating back to as early as the 10th century, it was not until 1491 that the first case was documented.
By performing an obstetric ultrasound at a gestational age of 10–14 weeks, monochorionic-diamniotic twins are discerned from dichorionic twins. The presence of a "T-sign" at the inter-twin membrane-placental junction is indicative of monochorionic-diamniotic twins (that is, the junction between the inter-twin membrane and the external rim ...