86  Patau Syndrome

Author

Dr. Phyllis Naa Djama Owiredu

86.1 Definition

Patau syndrome is a rare genetic disorder with the patient having an extra copy of chromosome 13 (Trisomy 13).

86.2 Genetics

Patau Syndrome is due most commonly to non-disjunction in meiosis, occurring more frequently in mothers of advanced age (greater than 35). Also, an unbalanced Robertsian translocation which results in 2 normal copies of chromosome 13 and an additional long arm of chromosome 13 can cause Edward’s syndrome. A less common cause is mosaicism which results in 3 copies of chromosome 13 in some cells and two copies in the others. Mosaics are the outcome of a mitotic non-disjunction error and are unrelated to maternal age. The prognosis is better in patients with mosaicism and patients with unbalanced translocations.

86.3 Clinical features

This extra copy of chromosome 13 disrupts normal embryonic development and leads to multiple defects. Some of these are:

  • CNS: Alobar holoprosencephaly, Anophthalmia, Microphthalmia, Coloboma, Intellectual disability, Hypotonia, Microcephaly, Seizures
  • Gastrointestinal: Exomphalos, Hernia, Meckel diverticulum, Omphalocele
  • Genitourinary: Polycystic kidneys, Cryptorchidism, Hypospadias, Labia Minora Hypoplasia
  • Cardiovascular: Ventricular Septal Defect, Atrial Septal Defect, Atrioventricualr Canal Defect, Tetralogy of Fallot
  • Skeletal: Polydactyly, Congenital talipes
  • Craniofacial: Cleft lip /cleft palate, Micrognathia
  • Others: Intrauterine Growth Restriction, Rocker bottom feet, Psychomotor disorders, Capillary hemangioma, Pre-auricular tags

86.4 Investigation

  • Prenatally with chorionic villi sampling, amniocentesis or fetal free DNA analysis.
  • Tissue microarray (especially in fetal death)
  • FISH(fluorescent in-situ hybridization)

86.5 Treatment

There is no definitive treatment for Patau syndrome. A multidisciplinary approach is required. Some of these include:

  • Counselling
  • Rehabilitation team/ palliative team
  • Occupational therapy
  • Psychology
  • Cardiology

86.6 Counselling

There should be genetic counselling offered to the parents. Genetic testing for parents The recurrence risk for Trisomy is approximately 0.5% above the mother’s age-related risk for autosomal trisomy. Consult a genetic counsellor or medical geneticist regarding recurrence risks for structural rearrangements that involve chromosome 13. Prognosis is generally poor (82% die within 1 month, 95% die within 6 months)