Comprehensive mutation screening in a cystic fibrosis center

Area of Science:

• Medical Genetics
• Molecular Biology
• Pulmonology

Background:

• Cystic Fibrosis (CF) diagnosis relies on identifying CFTR mutations, but over 800 exist, necessitating efficient screening.
• Current commercial tests for common CFTR mutations may not capture the full spectrum in diverse patient populations.

Purpose of the Study:

• To evaluate the sensitivity of a combined commercial testing and Single-strand conformation polymorphism/heteroduplex analysis (SSCP/HA) approach for comprehensive CFTR mutation detection.
• To establish the effectiveness of this multistage genotyping strategy in an ethnically diverse US cystic fibrosis center population.

Main Methods:

• Screened CFTR exons in 10 CF patients with unknown alleles after initial commercial testing.
• Compared results with 7 individuals exhibiting CF-like symptoms but negative sweat tests.
• Utilized SSCP/HA for mutation detection in conjunction with a standard 70-mutation commercial panel.

Main Results:

• The combined SSCP/HA and commercial approach identified 75% of unknown alleles in CF patients and detected 3 additional mutations in individuals with negative sweat tests.
• A total of 16 mutations were identified, including 7 missense and 9 other types (deletion, frameshift, nonsense, splicing).
• Three novel mutations (G970D, L1093P, 451-458Delta8 bp) and other new sequence changes were discovered.

Conclusions:

• Combining SSCP/HA with a 70-mutation commercial test achieves >95% detection of CFTR mutations in a heterogeneous CF center population.
• This multistage strategy enhances comprehensive genotyping for cystic fibrosis patients.
• Further investigation is warranted to explain the remaining undetected mutations.