Trisomy 13 Syndrome is a chromosomal disorder resulting in a syndrome characterized by specific (midline) dysmorphic features and organ malformations. Trisomy 13 occurs in one out of every 4,000 to 10,000 live births and affects the thirteenth set of chromosomes. Advanced maternal age is the contributing risk factor to Trisomy 13. Genetics contribute to seventy-five percent of all cases. A single defect during the first three weeks of development of the prechordal mesoderm can lead to morphologic defects of the midface, eyes, and forebrain and induction defects on the prosencephalon (cerebral hemispheres, diencephalon, hypothalamus, thalamus). Some facial abnormalities generally associated with Trisomy13 are: microcephaly with sloping forehead, aplasia cutis congenital, cleft lip and low set ears. Very often there are problems with the central nervous system like: holoprosencephaly, apn

eic sells, seizures, and severe mental retardation. Males tend to have cryptorchidism, abnormal scrotum, and ambiguous genitalia. Females often have a bicornate uterus. Trisomy 13 has a very poor diagnosis with: forty-five percent dying by one month, sixty-nine percent dying by six months, and seventy-two percent dying by twelve months.

Trisomy 18 Syndrome is a chromosomal disorder resulting in a syndrome characterized by specific (small) dysmorphic features and organ malformations. Trisomy 18 occurs in every one in eight thousand live births, affects the eighteenth set of chromosomes, most die in embryonic or fetal life, second most common autosomal aberration, and second most common multiple malformation syndrome. Risk factors are advanced maternal age with the female to male ratio is four to one. It was first recognized as a specific clinical entity by the discovery of an extra chromosome 18 in babies with a particular pattern of malformation by three independent groups (Edwards et al., Patau et al., Smith et al.) Genetics contribute to ninety of cases. Facial abnormalities include: microcephaly with prominent occiput, narrow bifrontal diameter, short palpabral fissures, low-set malformed ears, cleft lip, and micrognathia. Skeletal abnormalities include: webbed neck and

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