Preauricular Fistulae, Congenital

Clinical Features

Although in at least 1 family (Muckle, 1961) both ear pits and lateral cervical sinuses opening at various levels on the anterior margin of the sternomastoid were present, sometimes in the same individual, most families have shown either ear pits only or branchial cleft anomalies (113600) only. Hence, ear pits, which occur in the upper anterior end of the helix, are listed as a separate mutation.

Skin tags containing cartilage (Jenkins, 1928) occur in some affected persons (McKusick, 1964). These are considered abnormalities of the first branchial cleft. The family reported by Muckle (1961) showed 'buck teeth' (projecting upper front teeth).

Inheritance

Report of large kindreds such as that of Bhalla et al. (1979) in which there are no associated features or lateral cervical sinuses suggests that the trait is a distinct mendelian dominant.

Population Genetics

Ewing (1946) found ear pits in 0.9% of 3,500 British service men. They occur more frequently in blacks (Simpkiss and Lowe, 1961). Gualandri (1969) found 321 cases among 29,309 Milan school children. Pedigrees were prepared in 93 cases demonstrating autosomal dominant inheritance with about 85% penetrance. His use of the term fistula would be challenged by some who call the lesion a sinus or simply a pit.

Meggyessy and Mehes (1982) found the incidence of preauricular pits to be 0.47% among 6,766 unselected white Hungarian neonates and 0.30% in 7,215 hospitalized children. In most of the cases, the fistulae were unilateral and right-sided. Familial occurrence was never associated with major congenital disorders, whereas in one-third of the sporadic cases, serious congenital anomalies could be detected. They concluded that sporadic preauricular pits should be regarded as minor malformations of great significance in discovering hidden disorders and in syndrome identification.

Mapping

In a 3-generation Chinese family comprising 18 members, 7 of whom had preauricular fistulae, Zou et al. (2003) found linkage of the trait to a locus on 8q11.1-q13.3 (2-point lod score = 2.40 at theta = 0.0). Haplotype analysis regionalized the locus to a 26.5-cM interval between markers D8S532 and D8S279. That the lod score was less than 3.0 was attributed to the small family size. Genetic analysis excluded mutations in the EYA1 gene (601653).