OMIM ID:
Watson Syndrome
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Iris nodules similar to those seen in neurofibromatosis are found in some but not all patients with Watson syndrome.
Systemic Features
Short stature and low normal intelligence are the most consistent features. Pulmonic stenosis and cafe-au-lait spots are also common. The macrocephaly is relative and not striking. Neurofibromas have been seen in a minority of patients.
Genetics
Inheritance
Mutations in the NF1(17q11.2) gene have been identified in members of several large pedigrees with an apparent autosomal dominant pattern.
It remains uncertain if this condition is allelic to neurofibromatosis I(162200) or if Watson syndrome is the result of mutations in contiguous genes.
The LEOPARD syndrome(151100) shares some clinical similarities such as short stature, pulmonic stenosis, cognitive deficits and cafe-au-lait spots but is caused by mutations in PTPN11. The phenotype also resembles Noonan syndrome in some aspects.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission