In 2004, mutations on the CHD7 gene (located on Chromosome 8) were found in 10 of 17 patients in a study conducted in the Netherlands, making CHARGE an official syndrome.
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Most recently, a review of 379 published cases of clinically diagnosed cases of CHARGE syndrome in which CHD7 mutation testing was undertaken found that 67% of cases were due to a CHD7 mutation.
Male heterozygotes displayed abnormal pelvic elevation in a modified SHIRPA test and have a high incidence of Bergmeister's papilla in both eyes.
Other causes of IHH include GnRH insensitivity, which is the second most common cause of IHH and is thought to be responsible for up to 20% of cases, and a minority (less than 5-10%) due to inactivating mutations in a variety of other genes which positively regulate GnRH secretion such as CHD7, KISS1R, and TACR3.
CHD7 |