Amelogenesis Imperfecta, Type Ih

A number sign (#) is used with this entry because of evidence that amelogenesis imperfecta type IH (AI1H) is caused by homozygous or compound heterozygous mutation in the integrin beta-6 gene (ITGB6; 147558) on chromosome 2q24.


Amelogenesis imperfecta type IH is characterized by hypoplastic and hypomineralized tooth enamel that may be rough, pitted, and/or discolored (Wang et al., 2014 and Poulter et al., 2014).

Clinical Features

Wang et al. (2014) reported 2 Hispanic families segregating amelogenesis imperfecta. In Family 1, a 7-year-old girl had enamel malformations in the absence of other symptoms. She had mixed dentition that was yellow, with anterior open bite and class III malocclusion. The erupted teeth had undergone noticeable attrition, requiring crowns on the molars to maintain vertical dimension. On radiographs, the unerupted teeth had a thin enamel layer that contrasted well with dentin. Her nonconsanguineous parents were unaffected. In Family 2, an 8-year-old boy had enamel malformations. His secondary teeth were yellow-brown and rough-surfaced, and they displayed very little enamel except for a thin collar around the cervical margin. On radiographs, the teeth had a thin enamel layer that contrasted well with dentin. The patient was also noted to have Nance-Horan syndrome (302350). The patient's mother reported that her former husband and his brother had 'yellow teeth,' but neither man was available for examination.

Poulter et al. (2014) described 3 females from a consanguineous Pakistani family (AI-23) with amelogenesis imperfecta. The enamel on erupted teeth was near-normal in volume but was pitted and discolored. There was dramatic loss of enamel from the crowns of permanent molar teeth. Scanning electron microscopy of affected teeth showed that the enamel was punctured by numerous pits and that the prism array was more obscure than that of control enamel. The inner enamel layer was structurally abnormal, with loss of prism organization.


The transmission pattern of amelogenesis imperfecta type IH in the family reported by Poulter et al. (2014) was consistent with autosomal recessive inheritance.

Molecular Genetics

By whole-exome analysis in 2 Hispanic families in which only 1 member had with amelogenesis imperfecta, Wang et al. (2014) identified mutations in the ITGB6 gene in compound heterozygous state in 1 proband (A143T, 147558.0001; H275Q, 147558.0002) and in homozygous state in the other ( R616X; 147558.0003).

By whole-exome sequencing of a consanguineous Pakistani family segregating autosomal recessive amelogenesis imperfecta, Poulter et al. (2014) identified a homozygous missense mutation in the ITGB6 gene (P196T; 147558.0004) in 3 affected sisters. The parents were heterozygous for the mutation.