Novel method for identification of the lethal mutation in bovine APAF1 gene and its preliminary prevalence in Polish Holstein-Friesian bulls.

The aim of the study was to develop a reliable and cost-effective method for detection of nonsense mutation in APAF1 gene causing lethal effect called HH1 (Holstein Haplotype1) and to evaluate its prevalence in a sample of Polish Holstein-Friesian bulls. One hundred seventy eight bulls born between 1996 and 2017 were included in the analysis. They were kept in four artificial insemination centers and have in the pedigree the known carrier of HH1. All bulls were diagnosed by novel PCR-SSCP technique. Specific amplicons of 261 bp APAF1 gene fragment were used to detect changes in single stranded conformation (SSCP) caused by nonsense mutation C/T responsible for HH1. Each new carrier was used to trace another potential carriers among their offspring available in Polish Holstein Bull Repository Database. Among 178 bulls, 85 HH1 carriers were found. Our results show that nonsense mutation in APAF1 gene is already transmitted and segregating in Polish Holstein-Friesian cattle and its frequency may increase if no action will be undertaken against actual carriers.