Patau Syndrome (Trisomy 13-15)

• Neuro-developmental malformation due to a trisomy of chromosome 13-15

 

Clinical features include:

• Holoprosencephaly
• Failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres.
• The result is a single-lobed brain structure and severe skull and facial defects.
• In most cases of holoprosencephaly, the malformations are so severe that babies die before birth.
• In less severe cases, babies are born with normal or near-normal brain development and facial deformities that may affect the eyes, nose, and upper lip
• Arrhinencephaly

also called olfactory aplasia This term has been used as a synonym for holoprosencephaly. However, more recently it has been used to denote a condition where there is variable absence of the olfactory bulbs, tracts and anterior perforating substance without fusion of the hemispheres. It may represent the mildest form of telencephalic failure.

 

• Microcephaly
• abnormally small head, usually the result of a small brain (micrencephaly) either because of developmental anomalies like lissencephaly (“smooth brain” appearance seen in MRI, due to failure of gyri (normal bumps of the cortex) to form)
• Facial Features:
• Cleft Lip
• Hypertelorism (increased interorbital distance, a feature of many craniofacial congenital syndromes)

 

Edward’s syndrome

• Trisomy of Chromosome 18
• Clinical Features:
• Microcephaly