Recessive Mutations in ACP4 Cause Amelogenesis Imperfecta

Area of Science:

• Genetics
• Biochemistry
• Dentistry

Background:

• Amelogenesis imperfecta (AI) is a group of inherited disorders affecting tooth enamel formation and mineralization.
• AI presents with hypoplastic, hypomaturation, or hypocalcified enamel phenotypes.
• Recent studies implicated the ACP4 gene in hypoplastic AI, suggesting mutations may impair homodimerization or catalytic activity.

Purpose of the Study:

• To investigate the genetic basis of hypoplastic AI in Korean and Turkish families.
• To elucidate the functional consequences of identified ACP4 mutations on protein expression, homodimerization, and enzymatic activity.

Main Methods:

• Exome sequencing was performed on families with hypoplastic AI.
• Identified ACP4 mutations were analyzed using cloning, mutagenesis, immunofluorescence, and immunoprecipitation.
• Acid phosphatase activity assays were conducted to compare wild-type and mutant ACP4 function.

Main Results:

• Biallelic mutations in the ACP4 gene were identified in two families with hypoplastic AI.
• Mutant ACP4 proteins exhibited decreased expression levels.
• Mutant ACP4 showed reduced homodimerization ability and diminished acid phosphatase activity.

Conclusions:

• The study expands the known spectrum of ACP4 mutations associated with hypoplastic AI.
• Findings demonstrate that ACP4 mutations impair protein stability, homodimerization, and enzymatic function, contributing to defective amelogenesis.
• This research enhances the understanding of ACP4's role in normal and pathological tooth enamel development.