Question: How many people are affected by congenital central hypoventilation syndrome ?
Answer: CCHS is a relatively rare disorder. Approximately 1,000 individuals with this condition have been identified. Researchers believe that some cases of sudden infant death syndrome (SIDS) or sudden unexplained death in children may be caused by undiagnosed CCHS.
Source: GHR

Question: Is congenital central hypoventilation syndrome inherited ?
Answer: This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. More than 90 percent of cases of CCHS result from new mutations in the PHOX2B gene. These cases occur in people with no history of the disorder in their family. Occasionally an affected person inherits the mutation from one affected parent. The number of such cases has been increasing as better treatment has allowed more affected individuals to live into adulthood. About 5 to 10 percent of affected individuals inherit the mutation from a seemingly unaffected parent with somatic mosaicism. Somatic mosaicism means that some of the body's cells have a PHOX2B gene mutation, and others do not. A parent with mosaicism for a PHOX2B gene mutation may not show any signs or symptoms of CCHS.
Source: GHR