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Source: Wikipedia<\/span><\/p>\n<\/span>What Causes Noonan Syndrome?<\/span><\/h2>\nNoonan syndrome is caused by mutations in the genes<\/span> associated with the Ras \/ MAPK cell signaling pathway, which is required for normal cell division, proliferation<\/span>, differentiation<\/span> and migration. These mutations lead to loss of regulation of cell growth and division.<\/p>\nMutations in PTPN11<\/em> gene<\/span> are involved in more than 50% of Noonan syndrome cases. Genetic mutations in SOS1<\/em> are involved in the 10-15% of cases and mutations in the RAF1<\/em> gen and the RIT1<\/em> The genes represent approximately 5% each. Several other genes make up the rest.<\/p>\nthe genetic<\/span> The cause of Noonan syndrome is unknown in up to 20% of cases.<\/p>\n<\/span>What are the clinical features of Noonan syndrome? <\/span><\/h2>\nNoonan syndrome both sexes and all races; 50-70% of people with Noonan syndrome are short. Birth weight and length are usually normal, but growth slows over time. This is believed to be associated with abnormal levels of growth hormone.<\/p>\n
Noonan syndrome presents with distinctive facial features, such as:<\/p>\n