CHARGE syndrome stands for coloboma, heart defects, choanal atresia, retarded growth and development, genital abnormalities, and ear anomalies. A clinical diagnosis is made when an individual has all 4 major characteristics or 3 major and 3 minor. The major characteristics include coloboma, microphthalmos, choanal atresia or stenosis, cranial nerve dysfunction or anomaly, and characteristic ear. Minor features include genital hypoplasia such as micropenis, cryptorchidism, or hypoplastic labia, developmental delay, hypotonia, heart defect, growth deficiency, cleft lip and/or palate, tracheoesophageal fistula, and dysmorphic features.
CHARGE syndrome is inherited in an autosomal dominant manner. Most cases are de novo. If neither parent is affected, there is a 1-2% chance to have another child with CHARGE syndrome due to germline mosaicism.
Mutations in the CHD7 gene can also cause Kallmann syndrome type 5, which is characterized by isolated GnRH deficiency (IGD) and anosmia. IGD leads to hypogonadism and incomplete sexual maturation. CHD7 mutations account for approximately 5% of cases of Kallmann syndrome. Like CHARGE, Kallmann syndrome type 5 is also inherited in an autosomal dominant manner.
This laboratory performs Sanger sequencing of the CHD7 gene.