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Patau Syndrome Or Trisomy 13 – Causes, Symptoms And Caryotype

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Patau Syndrome Or Trisomy 13 – Causes, Symptoms And Caryotype

Trisomy 13 or Patau syndrome is the least common and most severe of autosomal trisomy, showing multiple abnormalities, most of which are incompatible with life. The clinical presentation of Patau syndrome was made in 1957 by Bartholini, but his authorship belongs to Patau, because he specifies the chromosomal etiology of the syndrome.

The incidence of Patau syndrome is 1 / 4000 – 1 / 10000 newborns. It is more common in girls, because boys have a reduced rate of survival. Mortality is high, 80% of patients with Patau syndrome die within the first month of life, 10% survive until age of one year.

Patau Syndrome

Patau Syndrome

Causes:

There is a significant association between advanced maternal age and Patau syndrome. Aneuploidy arise mainly due to non-disjunction in primary maternal meiosis.

The clinical presentation of Patau syndrome:

Patau syndrome is characterized phenotypically by:

  1. Head: microcephaly, scalp defects, malformed and lowset ears.
  2. Facial: sloping forehead, nose broad and flat, hypertelorism, hypotelorism, ocular anomalies such as microophthalmia or anophthalmia, absence of iris, cataract, iris coloboma, cleft lip and cleft palate.
  3. Neurologic: Holoprosencephaly, in which the brain is not divided completely into halves, is often present and is generally signaled by the presence of midline facial defects.
  4. Limbs: polydactyly or sindactyly.
  5. Cardiac malformations: represents 80% of all malformations: patent ductus arteriosus, ventricular septal defect, interatrial septal defect, dextrocardia.
  6. Genitourinary malformations: polycystic kidney, renal duplicaton, double ureter, testicular agenesis and cryptorchidism in boys, clitoral hypertrophy and two-horned uterus in girls.
  7. Capillary hemangiomas on the face, forehead and neck.
Baby with Patau syndrome

Baby with Patau syndrome

Karyotype:

  • Patau syndrome homogeneous or uniform trisomy, karyotype is 47, XX+13 or 47, XY+13;
  • Patau syndrome in mosaic or mosaic trisomy, karyotype is 47,XX+13 / 46,XX or 47,XY+13 / 46,XY.

Prenatal diagnosis:

Patau syndrome is suspected because of prenatal ultrasound detected changes: nuchal translucency, heart defects, neural tube defect  and the certainty diagnosis can be made by cytogenetic analysis of amniotic fluid or of fetal blood and chorionic villi biopsy.

Genetic consultation:

Genetic counseling and genetic testing is aimed especially for the parents carriers of 13 chromosome translocation and have a child with Patau syndrome, to prevent the recurrency of this chromosomal anomalies, the risk is 1%.