Patau Syndrome, which is also known as Trisomy 13. Patau Syndrome is a severe genetic disorder caused by the presence of an extra chromosome 13.

Genetic Cause:

• Chromosomal Basis: Patau Syndrome occurs when a person has three copies of chromosome 13 instead of the usual two. This extra chromosome can cause a range of severe physical and intellectual disabilities.

• Genetic Mechanism: The extra chromosome can be due to nondisjunction during the formation of reproductive cells, leading to an extra chromosome in the fertilized egg.

Incidence:

• The syndrome is rare, occurring in about 1 in 10,000 to 1 in 16,000 live births.

Clinical Features:

• Craniofacial Abnormalities: These may include microphthalmia (small eyes), microcephaly (small head), cleft lip and/or palate, and low-set ears.

• Neurological Defects: Severe intellectual disability and brain structural anomalies like holoprosencephaly, where the brain doesn't divide properly into the right and left hemispheres.

• Heart Defects: Commonly include ventricular septal defects, atrial septal defects, and patent ductus arteriosus.

• Gastrointestinal Abnormalities: Omphalocele (where abdominal organs protrude into the umbilical cord) or other malformations.

• Limb Abnormalities: Polydactyly (extra fingers or toes), clenched fists, and other skeletal anomalies.

• Genitourinary Malformations: Kidney abnormalities and underdeveloped genitalia.

Diagnosis:

• Prenatal Screening: Ultrasound and maternal blood tests can indicate the possibility of trisomy 13.

• Diagnostic Testing: Amniocentesis or chorionic villus sampling (CVS) followed by karyotyping can confirm the diagnosis.

• Postnatal Diagnosis: Physical examination and karyotyping of the newborn's cells.

Prognosis:

• Patau Syndrome is associated with high mortality; many affected infants die within the first few weeks or months of life. However, some may survive longer with supportive care, though they often have severe developmental and health issues.

Management:

• Supportive Care: Focuses on managing symptoms and providing supportive care, which may include surgery for congenital malformations, physical therapy, and nutritional support.

• Genetic Counseling: Important for affected families to understand the recurrence risk and implications for future pregnancies.

Additional Information:

• Epidemiology: It affects both sexes equally and can occur in any population.

• Prevention: Currently, there are no known measures to prevent Patau Syndrome due to its spontaneous genetic nature.