José Luis Lezana

G542X mutation in Mexican cystic fibrosis patients

We analyzed the frequency of the G542X mutation in a sample of 76 Mexican cystic fibrosis patients and the genotype‐phenotype correlation. The mutation was screened using PCR‐mediated site‐directed mutagenesis, and was present on 7.2% of the CF chromosomes. This frequency is significantly higher than the worldwide frequency according to the Cystic Fibrosis Genetic Analysis Consortium (3.4%, p<0.01), and similar to that reported in Spain (8%), which is in accordance with the ethnic origin of the Mexican population. All patients carrying G542X on at least one allele had mild to moderate pulmonary disease. In patients with hepatobiliary involvement, the frequency of G542X chromosomes was higher than the frequency of the mutation in all the Mexican CF chromosomes.

Two novel frameshift deletions (1924del7, 2055del9→A) in the CFTR gene in Mexican cystic fibrosis patients

Lorena Orozco,* Julian Zielenski, Danuta Markiewicz, Teresa Villarreal, Lap-Chee Tsui, Jose Luis Lezana, and Rosa M del Angel Molecular Biology Laboratory, Human Genetics Department, Instituto Nacional de Pediatria, Mexico City, Mexico Department of Genetics, Hospital for Sick Children, Toronto, Canada Department of Molecular and Medical Genetics, University of Toronto, Toronto, Canada Asociacion Mexicana de Fibrosis Quistica, Mexico City, Mexico Department of Experimental Pathology, CINVESTAV-IPN, Mexico City, Mexico

Mild cystic fibrosis disease in three Mexican delta-F508/G551S compound heterozygous siblings

We describe three delta‐F508/G551S compound heterozygous siblings with a mild CF phenotype, characterized by mild chronic pulmonary disease, pancreatic sufficiency and increased sweat chloride levels. PCR‐mediated site‐directed mutagenesis detected the delta‐F508 mutation on one allele, and the G551S mutation was detected by SSCP and sequence analysis of exon 11. Two previously described sisters who were homozygous for the G551S mutation had a very mild phenotype with normal sweat chloride concentrations. In our patients the mild phenotype resulted from the combined effect of the mild G551S allele with the severe delta‐F508 allele.