Amelogenesis imperfecta and gingival fibromatosis syndrome is an autosomal recessive condition characterized by mild gingival fibromatosis and dental anomalies, including hypoplastic amelogenesis imperfecta, intrapulpal calcifications, delay of tooth eruption, hypodontia/oligodontia, pericoronal radiolucencies, and unerupted teeth (Martelli-Junior et al., ... Amelogenesis imperfecta and gingival fibromatosis syndrome is an autosomal recessive condition characterized by mild gingival fibromatosis and dental anomalies, including hypoplastic amelogenesis imperfecta, intrapulpal calcifications, delay of tooth eruption, hypodontia/oligodontia, pericoronal radiolucencies, and unerupted teeth (Martelli-Junior et al., 2008).
Martelli-Junior et al. (2008) described 4 patients in a 3-generation, consanguineous family with a syndrome of gingival fibromatosis and dental anomalies. The patients, 3 females and a male, had yellow teeth with thin enamel of normal hardness, gingival ... Martelli-Junior et al. (2008) described 4 patients in a 3-generation, consanguineous family with a syndrome of gingival fibromatosis and dental anomalies. The patients, 3 females and a male, had yellow teeth with thin enamel of normal hardness, gingival fibromatosis, unerupted teeth, and coronal and radicular pulpal calcifications. Histologic analysis of the gingival overgrowth showed a well-structured epithelium with elongated and thin papillae inserted in fibrous connective tissue. The connective tissue showed an increased amount of collagen fiber bundles running in all directions. None of the patients had a history of renal impairment and all had normal renal ultrasound scans and normal calcium levels in the serum (see 204690). Mental retardation was segregating independently in this family (O'Sullivan et al., 2011).
By whole-exome sequencing, O'Sullivan et al. (2011) identified a homozygous nonsense mutation in exon 2 of the FAM20A gene (R136X; 611062.0001) segregating with the syndrome in the family reported by Martelli-Junior et al. (2008). The mutation was not ... By whole-exome sequencing, O'Sullivan et al. (2011) identified a homozygous nonsense mutation in exon 2 of the FAM20A gene (R136X; 611062.0001) segregating with the syndrome in the family reported by Martelli-Junior et al. (2008). The mutation was not present in the dbSNP database, the 1000 Genomes database, or the CEPH Diversity Panel. O'Sullivan et al. (2011) demonstrated that mouse Fam20a is expressed in ameloblasts and gingivae. In affected members of 4 of 9 families with an amelogenesis imperfecta phenotype resembling that of the family with AIGFS reported by Martelli-Junior et al. (2008), Cho et al. (2012) identified homozygous or compound heterozygous mutations in the FAM20A gene (611062.0002-611062.0006). None of the affected mutation-positive individuals had any extra-oral syndromic features, and all had generalized hypoplastic enamel with yellowish hue, varying degrees of gingival hyperplasia, and delayed or failed eruption of permanent teeth with dilaceration of the root. Late-developing teeth were particularly susceptible to impaction and root dilaceration.