Patau Syndrome: A Rare and Upsetting disorder

I studied Patau syndrome very briefly during second year of university. 

Patau syndrome was first reported by Patau (1960) and is also known as trisomy 13, the condition is the most severe and the third most common trisomy behind Edwards and Down syndrome. The standard karyotype has a typical 46XX chromosome algorithm for females and XY males. Aneuploidy is a genetic disorder in which a fetus has an extra or missing chromosome, and can occur in about 1 in 150 babies. Patau syndrome is a chromosomal disorder in which a person has three copies of chromosome 13. Edwards is a trisomy 18 and Down syndrome is a trisomy 21. 

Chromosome 13 is transmitted to some or all of the cells in the growing embryo and is existent in 1:12000 live births with median survival age being 2.5 days. Patient mortality is 82% within the first month of birth reports. ).Tunca et al (2001) states that only five reported patients diagnosed with trisomy 13 have lived past a decade. Central nervous system (CNS), kidney, heart and physical complications can occur due to the additional genetic material, making survival to adulthood extremely rare. Chromosome 13 embodies between 3.5%-4% of total DNA and comprises of between 600-700 genes, total estimated chromosome 13 genes in the human genome is between 20,000-25,000. These genes include ATPase Cu++ transporting beta polypeptide (ATP7B), collagen, type IV alpha 1 (COL4A1) and endothelin receptor type B (EDNRB).

Trisomy occurs from non-disjunction of the chromosome during anaphase during meiosis l and ll, therefore gametes are produced with too many chromosomes. Robertsonian translocation can also cause Patau syndrome, when the long arm of chromosome 13 fuses to the centromere of additional acrocentric chromosome. Robertsonian translocation occurs from chromosomes 13, 14, 15, 21 and 22.

Symptoms that occur with trisomy 13 include;

• ·  Nervous system disoders, which include mental retardation, motor disorder, microcephaly, spina bifida, holoprosencephaly, meningomyelocele and structural eye defects.
• ·  Musculoskeletal and cutaneous disorders which include low-set ears, rocker-bottom feet, polydactyly, cleft palate and abnormal palm pattern.
• ·  Kidney defects including polycystic disease.
• ·  Heart defects.
• Because of the severity of some of these abnormalities, mortality rate is extremely high.

Facts about trisomy 13 include;

• ·  The most common causes of death from Patau syndrome are cardiopulmonary arrest (69%), congenital heart disease (13%) and pneumonia (4%).
• ·  In the United States, approximately 1 case in 8,000-12,000 live births is born with trisomy 13.
• ·  Extrapolation statistics of Patau syndrome incidence in the United Kingdom was 12,054 in an estimated population used at 60,270,708.
• ·  Patau syndrome incidence (extrapolated statistics) in China was 259,769 in an estimated population of 1,298,847,624.
• ·  There is no evidence of racial or geographic differences having a significant effect on Patau syndrome rate; however evidence suggests that increased maternal age is more likely to cause trisomy 13. The parental origin of the extra chromosome 13 is approximately 83% maternal and 17% paternal.

RReferences 

Tunca, Y., Kandale, J.S. and Pivnick, E.K. (2001). Long-term survival in Patau syndrome. Clin. Dysmorphol. 10: 149-150.