Improving mutation screening in familial hematuric nephropathies through next generation sequencing

Area of Science:

• Genetics
• Nephrology
• Molecular Biology

Background:

• Alport syndrome is an inherited kidney disease caused by mutations in type IV collagen genes.
• COL4A5 mutations cause X-linked Alport syndrome, while COL4A3 and COL4A4 mutations cause autosomal forms and benign familial hematuria.
• Traditional mutation screening for these genes is time-consuming and costly.

Purpose of the Study:

• To evaluate the efficiency and cost-effectiveness of next-generation sequencing (NGS) for simultaneous mutation screening of COL4A3, COL4A4, and COL4A5 in Alport syndrome patients.
• To identify novel mutations and large rearrangements in these genes.
• To assess the frequency of different inheritance patterns.

Main Methods:

• Multiplex PCR, amplicon quantification, and NGS were used to analyze COL4A3, COL4A4, and COL4A5 in 101 unrelated patients.
• Sanger sequencing and Integrative Genomics Viewer were used for secondary analysis.
• Mutation identification and characterization were performed.

Main Results:

• 88 mutations and 6 variants of unknown significance were identified in 83 patients.
• 75 of the identified mutations were novel.
• NGS facilitated the detection of large COL4A3 and COL4A4 rearrangements, previously undescribed.
• The study found a higher proportion of mutations in COL4A3 and COL4A4, suggesting autosomal dominant Alport syndrome is more frequent than previously reported.

Conclusions:

• NGS is an efficient and cost-effective method for simultaneous screening of Alport syndrome genes.
• This approach reduces screening time and costs, aiding in diagnosis and genetic counseling.
• The findings suggest a higher prevalence of autosomal dominant Alport syndrome and highlight the utility of NGS in identifying complex genetic alterations.