PKU in Minas Gerais State, Brazil: mutation analysis

Area of Science:

• Genetics
• Molecular Biology
• Population Genetics

Background:

• Phenylketonuria (PKU) is an inborn error of metabolism.
• Understanding the genetic basis of PKU is crucial for diagnosis and management.
• Brazil's diverse population, including European, African, and Amerindian admixture, presents a unique context for studying genetic diseases.

Purpose of the Study:

• To determine the phenylketonuria (PKU) mutational spectrum in Minas Gerais, Brazil.
• To establish the relative frequency of these mutations within the state.
• To investigate the origin of these mutations using haplotype analysis.

Main Methods:

• Analysis of all 13 exons, splicing sites, and the promoter region of the PAH gene in 78 PKU patients.
• Identification and characterization of mutations.
• Haplotype determination to trace the ancestral origin of PAH alleles.

Main Results:

• Identified 30 different mutations, establishing 98% of the PAH alleles.
• Discovered a novel mutation, Q267X.
• The most common mutations (V388M, R261Q, IVS10-11G>A, I65T, IVS2+5G>C, R252W, IVS2+5G>A, P281L, L348V) account for 80% of PKU alleles.
• The majority of mutations and their haplotypes are common in the Iberian Peninsula.
• Some mutations were rare in Europe, and four new mutation-haplotype associations were found.
• I65T and Q267X mutations, associated with haplotype 38, may have African origins or resulted from Brazilian miscegenation.

Conclusions:

• The PKU mutational spectrum in Minas Gerais is largely influenced by European ancestry.
• Evidence suggests African contributions to the PKU gene pool, possibly through historical admixture.
• The study provides valuable insights into the genetic diversity of PKU in a trihybrid population.