Paper type: Original Research Polymorphism of the ovine BMP15, INHBA and INHA candidate genes for litter size in four Iranian Indigenous sheep using PCR-sequencing Mustafa Muhaghegh Dolatabady *, Sahar Safari, Parisa Aslanlo, Hamid Soleimani and Javad Habibi Zad Department of Animal Science, Faculty of Agricultural Science, University of Yasouj, Yasouj, Iran * Corresponding author, Tel: +98 9173416832 E-mail address: mmuhaghegh@yu.ac.ir Received: 12 Feb 2022, Accepted: 28 Aug 2022, Published online: 05 Dec 2022, © The authors, 2022. ORCID Mustafa Muhaghegh Dolatabady 0000-0003-4876-1514 Sahar Safari 0000-0002-9745-5698 Parisa Aslanlo 0000-0003-4674-0773 Hamid Soleimani 0000-0003-0565-2828 Javad Habibi Zad 0000-0003-2802-1260 Abstract The inhibin α (INHA), inhibin βA (INHBA) and bone morphogenetic protein 15 (BMP-15) were investigated as candidate genes for reproductive traits in four Iranian sheep breeds (Bahmaei, Lak Ghashghaei, Lori-Bakhtiari and Karakul). Based on the ovine sequences of BMP-15, INHA and INHBA genes, three pairs of primers were designed to identify single nucleotide polymorphisms (SNPs) in exon 2 of BMP-15, INHA and INHBA in multiparous ewes by DNA sequencing. Two SNPs were detected in exon 2 of the ovine BMP15 gene at positions 367 and 430, which lead to amino acid substitutions at position 231 and 252 in the BMP15 protein sequence, respectively. Substitution of Leucine to Proline at position 252 is predicted to affect the protein function. A synonymous mutation was found in the amplified fragment of exon 2 at position 752 in ovine INHBA gene. In addition, the c752C>T mutation was only found in heterozygous condition in only one Lori-Bakhtiari ewe, while other breeds were in wild type genotype for c752C>T mutation. The INHA gene was shown to be highly polymorphic. A total of 7 SNPs including 6 nucleotide substitutions and one insertion were found in the amplified fragment of the INHA locus. The insertion mutation was found in two animals of Bahmaei and Karakul breeds. Interestingly, homozygous condition for the mutant alleles in all identified SNPs in BMP15, INHA and INHBA loci was absent in these breeds. Generally, these breeds showed different genetic structures with regard to the identified SNPs in BMP15, INHBA and INHA genes. However, further research with larger sample size and phenotype data on reproductive performance is required to investigate the definitive effect of the identified mutations in this study. Keywords: BMP15, INHA, INHBA, litter size, sheep breeds Introduction anisms of some reproductive features, including the num- Currently, there are more than 1400 sheep breeds in the wo- ber of mature follicles and ovulating rate in many sheep rld that differ in many performance features, including the rep- breeds, have been investigated. It has been confirmed t- roductive traits (National Sheep Association, 2021). The ewes hat sheep fertility can be determined by polygenic or det- usually gives birth to 1 or 2 lambs at each lambing, but there ermind by the segregation of a major gene named the fe- are some highly prolific sheep breeds with litter size ranging fr- condity (Fec) gene (Kaczor, 2017). Many studies have re- om 3 to 6 lambs (Kaczor, 2017). Currently, the genetic mech- ported that genetic polymorphisms in Fec gene family co- 2022, 10 (2): 1-8 DOI: 10.22103/JLST.2022.19012.1397 http://lst.uk.ac.ir