Genetic Counselling in a Familial Deletion 18p Syndrome

Deletion of 18p syndrome (del18p), is a chromosomal aberration described by the french geneticist Jean de Grouchy in 1963, known to be compatible with long-term survival. About 1 in 50,000 babies is born with a deletion of 18p and more than one hundred cases have been reported.

Most reports suggest that 18p deletions affect girls more often than boys (female to male ratio is 3:2). Phenotypic manifestations of this deletion are very sparse at birth, but during life may consist in: mental retardation, developmental delay and learning difficulties, growth retardation, craniofacial dysmorphism and abnormalities of the limbs (clinodactyly of the fifth finger), genitalia, brain (for example holoprosencephaly, in 10% of the cases), eyes, and heart.

It seems that beside the typical manifestations of that syndrome, the girl had an abnormality of thyroxine synthesis, most likely a coupling defect. After Jones KL (2006), there is a significant discrepancy between verbal and non-verbal performance, verbal performance being more severely affected.

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