Choanal Atresia, Posterior
Choanal atresia is a threat to life because young infants cannot establish the habit of mouth breathing. About 8% of cases are familial (Gorlin, 1982). It is probably a multifactorial trait like cleft lip and cleft palate. The fact that both affected successive generations and affected single generations have been reported supports this (Lang, 1912; Phelps, 1926; McGovern, 1950). Ransome (1964) found 12 families with 2 or more members affected. One of these, in which 4 of 5 sibs were affected, was described by him. Most reports of multiple affected relatives have concerned sibs. However, affected persons in the family reported by Lang (1912) included, in addition to the proband, the mother, sister and maternal aunt and perhaps a brother. Fendel (1966) described affected sibs. Grahne and Kaltiokallio (1966) observed affected sisters. The condition is said to occur twice as often in girls as in boys and more frequently in the right side than the left side.
PCA has been observed with the Treacher Collins syndrome (154500) and with hyperostotic dwarfism (151050). Shashi et al. (1994) described choanal atresia in a patient with the deletion 9p syndrome (9p- syndrome; 158170) and found a previous report of this association. Shashi et al. (1998) reported a third case of deletion 9p with choanal atresia.
Harris et al. (1997) examined data from 3 large registries of congenital malformations and identified 444 infants with choanal atresia, for an average rate of 0.82 affected per 10,000 births. No statistically significant difference in rate was noted for race, sex, maternal age or parity, or laterality in unilateral cases; however, a slightly increased risk at twinning was noted. An analysis of associated malformations, present in 47% of the infants without chromosome anomalies, indicated that a weak, nonrandom association can be demonstrated between the malformations of the CHARGE complex (214800). If the definition of CHARGE is the presence of 3 or more malformations, then of the 444 infants identified, 7% belonged to the CHARGE constellation. Harris et al. (1997) concluded that for the term CHARGE to be meaningful, it should be restricted to infants with multiple malformations and choanal atresia and/or coloboma, combined with other cardinal malformations (heart, ear, and genital), for a total of at least 3 cardinal malformations; growth retardation, especially low birth weight, should not be used in the definition.
Greenberg (1987) described the association of choanal atresia and absent nipples, athelia (113700), in an infant girl born to a woman treated for hyperthyroidism throughout pregnancy with methimazole and propranolol. The question of methimazole teratogenicity was raised. Greenberg (1987) pointed out that Qazi et al. (1982) found several children with associated hypoplasia of the nipples and posterior choanal atresia. Wilson et al. (1998) also described choanal atresia and underdevelopment of the nipples as consequences of in utero exposure to methimazole given in the treatment of maternal Graves disease (275000). Barbero et al. (2004) described 3 patients with choanal atresia whose mothers received methimazole during pregnancy for the treatment of thyrotoxicosis.
Gershoni-Baruch (1992) described a small inbred Arab Moslem kindred in which nonsyndromal choanal atresia occurred in 2 sibs and their paternal uncle. In a note added in proof, she reported the birth of a third affected sib.
Ramos-Arroyo et al. (2000) reported the cases of 3 members of a family who had congenital choanal atresia; 2 of these also had maxillary hypoplasia, prognathism, and hypodontia. Four other relatives had either maxillary hypoplasia and/or prognathism.
Al-Gazali et al. (2002) reported a brother and sister from an inbred Arab family with an autosomal recessive syndrome of choanal atresia, hypothelia/athelia, and thyroid gland anomalies. The sister died at 4 months of age. The authors noted that the features overlapped those of Bamforth syndrome (241850), HEDH syndrome (225050), and methimazole embryopathy.