Abstract
Amelogenesis imperfecta is a group of inherited diseases affecting the quality and quantity of dental enamel. To date, mutations in more than ten genes have been associated with non-syndromic amelogenesis imperfecta (AI). Among these, ENAM and LAMB3 mutations are known to be parts of the etiology of hypoplastic AI in human cases. When both alleles of LAMB3 are defective, it could cause junctional epidermolysis bullosa (JEB), while with only one mutant allele in the C-terminus of LAMB3, it could result in severe hypoplastic AI without skin fragility. We enrolled three Chinese families with hypoplastic autosomal-dominant AI. Despite the diagnosis falling into the same type, the characteristics of their enamel hypoplasia were different. Screening of ENAM and LAMB3 genes was performed by direct sequencing of genomic DNA from blood samples. Disease-causing mutations were identified and perfectly segregated with the enamel defects in three families: a 19-bp insertion mutation in the exon 7 of ENAM (c.406_407insTCAAAAAAGCCGACCACAA, p.K136Ifs*16) in Family 1, a single-base deletion mutation in the exon 5 of ENAM (c. 139delA, p. M47Cfs*11) in Family 2, and a LAMB3 nonsense mutation in the last exon (c.3466C>T, p.Q1156X) in Family 3. Our results suggest that heterozygous mutations in ENAM and LAMB3 genes can cause hypoplastic AI with markedly different phenotypes in Chinese patients. And these findings extend the mutation spectrum of both genes and can be used for mutation screening of AI in the Chinese population.
Highlights
Amelogenesis imperfecta (AI) is a group of inherited diseases that exhibit enamel malformations with diverse phenotypes and genetic heterogeneity [1,2,3]
The spacing of the mandibular anterior teeth was clearly secondary to the thin enamel on the crowns
We found three novel heterozygous ENAM and LAMB3 mutations
Summary
Amelogenesis imperfecta (AI) is a group of inherited diseases that exhibit enamel malformations with diverse phenotypes and genetic heterogeneity [1,2,3]. The term is applied to indicate the presence of an enamel phenotype in syndromes [4]. AI has been categorized as hypoplastic, hypocalcified, hypomaturized, and hypoplastic-hypomaturized types [1]. Mutations in the AMELX, ENAM, AMBN, MMP20, KLK-4, FAM83H, WDR72, SLC24A4, C4orf, ITGB6, and LAMB3 genes have been found to cause non-syndromic AI in human patients [5,6,7,8,9,10,11,12,13,14]. ENAM (OMIM 606585) and LAMB3 (OMIM 150310) mutations.
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