Role of genetic introgression in introducing mutant alleles in Bos indicus cattle and prevalence of lethal genetic disorders in Bos taurus × Bos indicus and Bos indicus cattle in India.

Fertility is an important trait associated with reproductive performance and animal welfare concern. Lethal alleles affect fertility through early embryonic death, abortions, and stillbirth depending on the genetic expression of the allele. Holstein Friesian and Jersey are two major Bos taurus breeds used widely for increasing milk yield along with purebreds of Bos indicus breeds like Gir, Kankrej, Sahiwal, and Tharparkar. In the present study, prevalence of lethal mutants in crossbred Holstein Friesian (CBHF, n = 2435), crossbred Jersey (CBJY, n = 2874), Gir (n = 3288), Kankrej (n = 593), Sahiwal (n = 965), and Tharparkar (n = 18) were studied. Heterozygous carrier animals were identified for bovine leukocyte adhesion deficiency (BLAD), Citrullinemia, complex vertebral malformation (CVM), Brachyspina, Holstein Haplotype 1 (HH1), Holstein Haplotype 3 (HH3),Holstein Haplotype 4 (HH4) and Jersey Haplotype 1 (JH1). Breed purity analysis confirmed inheritance of Bos taurus genes contributing to the presence of lethal mutant alleles like BLAD, Citrullinemia, HH1, and JH1 in apparently phenotypic Bos indicus animals. Screening and elimination of heterozygous carrier bulls/cows is essential to control fertility loss associated with lethal alleles.

Novel mutation in UMPS gene leads to false positive result of DUMPS (genetic disorder) in buffaloes: need for gene sequencing before confirming results of RFLP in new species.

Deficiency of uridine monophosphate synthase (DUMPS) is a lethal genetic disorder associated with early embryonic mortality. Murrah and Mehsana male buffaloes (n = 594) were screened for DUMPS by PCR-RFLP technique. A few Murrah buffalo male calves were found to be carriers of DUMPS in RFLP, which has not been reported earlier. On the Sanger sequencing, a novel A to G substitution mutation was identified in AvaI restriction recognition site of UMPS gene in buffaloes. This mutation hinders digestion of DNA by AvaI which leds to false positive results for DUMPS carrier in RFLP. The results indicated that genome sequencing must be performed before confirming results of RFLP in any new species. All the buffaloes that were tested had only wild-type genotype in exon 5 for DUMPS specific allele.