Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome, also known as deletion 4p and 4p- syndrome was first described in 1961 by U. Wolf and K. Hirschhorn and their co-workers. It is a characteristic phenotype resulting from a partial deletion of chromosomal material of the short arm of chromosome 4.

Signs and symptoms
The most common abnormalties seen include severe to profound mental retardation, microcephaly, seizures, hypotonia, and cleft lip and/or palate. Characteristic facial features, include strabismus, hypertelorism, down-turned "fishlike" mouth, short upper lip and philtrum, small chin, ear tags or pits, and cranial asymmetry. Occasional abnormalities include heart defects, hypospadias, scoliosis, ptosis, fused teeth, hearing loss, delayed bone age, low hairline with webbed neck, and renal anomalies. They are described as happy, loving children.

Genetics
Wolf-Hirshhorn syndrome is caused by a partial deletion of the short arm of chromosome 4. About 87% of cases represent a de novo deletion, while about 13% are inherited from a parent with a chromosome translocation. In the cases of familial translocation, there is a 2 to 1 excess of maternal transmission. However, the de novo cases, 80% are paternally derived. The symptoms and phenotype do not differ based on the size of the deletion. The critical region for determining the phenotype is at 4p16.3 and can often be detected through genetic testing and fluorescent in situ hybridization (FISH). Genetic testing and genetic counseling is offered to affected families.