Alport syndrome. Molecular genetic aspects

Area of Science:

• Genetics
• Molecular Biology
• Nephrology

Background:

• Alport syndrome (AS) is a progressive hereditary kidney disease with hearing and vision complications.
• X-linked inheritance, caused by COL4A5 gene mutations, accounts for 85% of AS cases.
• Accurate genetic diagnosis is crucial for carrier detection, prenatal diagnosis, and genetic counseling.

Purpose of the Study:

• To develop and validate efficient molecular diagnostic methods for detecting COL4A5 gene mutations in Alport syndrome.
• To identify novel mutations and characterize genotype-phenotype correlations for improved prognosis prediction.
• To establish an algorithm for molecular genetic analysis of the COL4A5 gene in suspected AS cases.

Main Methods:

• Multipoint linkage analysis and positional cloning efforts for X-linked AS.
• Southern blotting and MLPA for detecting large structural rearrangements (deletions, duplications, inversions).
• PCR-SSCP and direct sequencing for exon-by-exon mutation screening; RT-PCR for mRNA analysis.

Main Results:

• Identified 64 distinct COL4A5 mutations in 72 families, with a 53% overall mutation detection rate.
• Glycine substitutions in the collagenous domain were the most frequent mutation type (47%).
• Truncating COL4A5 mutations correlated with an earlier onset of end-stage renal disease (ESRD) in males.

Conclusions:

• Developed a sensitive and efficient molecular diagnostic approach for COL4A5 gene analysis in AS.
• COL4A5 mutation analysis can predict ESRD onset in male patients, though genotype-phenotype correlations are not always distinct.
• The study provides a basis for improved genetic counseling and highlights AS as a candidate for future gene therapy.