Trisomy D and trisomy 13 are other names for Patau syndrome. It is a chromosomal abnormality in which an individual has an extra chromosome 13. the causes may be Robertsonian translocations or during meiosis, due to non-disjunction of chromosomes.
The additional chromosome 13 destroys the normal stages of development, causing kidney and heart defects. The incidence of the syndrome is 1 in 10,000 live births. This article gives information about Patau syndrome which can cause eye defects.
Manifestations and Physical Findings
Common abnormalities of child born with this defect may include:
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Nervous system
- microcephaly
- mental and motor challenged
- holoprosencephaly (fore brain failure to divide properly)
- meningomyelocele (spinal defect)
- structural eye defects which include Peters anomaly, microphthalmia, cataract, fundus or iris (coloboma), retinal detachment or retinal dysplasia, cortical visual loss, optic nerve hypoplasia and nystagmus.
- low-set ears
- polydactyly(extra digits)
- prominent heel
- omphalocele (abdominal defect)
- rocker bottom feet (deformed feet)
- abnormal palm pattern
- cutis aplasia (some portion misses either of the hair or skin)
- fingers overlapping over thumb
- cleft palate
- kidney defects
- abnormal genitalia
- single umbilical artery
- heart defects
Musculoskeletal and cutaneous
Urogenital
Other
Causes of Patau Syndrome
- In most of the cases, this syndrome result from trisomy 13. This means usually, each cell present in the body has two copies of chromosome 13 but people with this defect have three copies of chromosome 13.
- Other cause may be due to the attachment of chromosome 13 to another chromosome before conception or at conception. Affected individuals have two copies of chromosome 13, in addition extra material from this chromosome attached to another chromosome.
- In most cases, this syndrome is not inherited. It occurs as random events during the reproductive cells formation. If there is an error in cell division, which is called non-disjunction, it can result in cells with an abnormal chromosomal number.
- Patau syndrome resulted from translocation can be inherited.
