Short Communication: Predominance of β-Casein (CSN2) C Allele in Goat Breeds Reared in Italy

Abstract

A protocol for the rapid and simultaneous genotyping of A, C, and 0 'CSN2 alleles in goat was developed by single strand conformational polymorphism polymerase chain reaction (SSCP-PCR) technique. Screening the CSN2 variability in 7 goat breeds reared in Italy validated the genotyping test. The SSCP-PCR technique was also suitable for monitoring CSN2 polymorphism. In particular, the discrimination between CSN2*A and CSN2*C is important because the 2 corresponding protein variants cannot be separated by standard typing techniques. The monitoring of CSN2 variability in the goat breeds indicates the predominance of the C allele. In most breeds, CSN2*C occurred with the highest frequency, except in Saanen where CSN2*A and CSN2*C showed similar frequencies. Variant CSN2*C occurred with a frequency of 0.68 (Camosciata), 0.70 (Jonica), 0.71 (Garganica), 0.82 (Maltese), 0.87 (Cilentana), and 0.97 (Orobica). The alignment among the mature CSN2 sequences of different species suggests that CSN2*A is the ancestral allele compared with CSN2*C. Interestingly, the CSN2*A goat variant showed higher frequencies in selected breeds (Saanen and Camosciata).

Genetic Characterisation ofCSN2Gene inGirgentanaGoat Breed

“…The 0 allele was not genotyped because it has been identified only in Creole and Pyrenean goat breeds (Persuy et al, 1999). The first protocol was used to amplify a 374 bp fragment of exon 7 using primers and PCR conditions by Chessa et al (2005) in order to discriminate A/A1, C/C1, E, and 0' alleles. The second protocol was used to discriminate allele C to C1 amplifying a 325 bp fragment of exon 9 using primers by Chessa et al (2008) and PCR conditions by Chessa et al (2005) with an annealing temperature of 56°C.…”

“…At least, ten alleles have been identified in goat CSN2 gene. In particular, seven of these alleles (A, A1, C, C1, E, 0, and 0') were characterised at DNA level (Rando et al, 1996;Persuy et al, 1999;Chessa et al, 2005Chessa et al, , 2008Cosenza et al, 2005), whereas B and D alleles were described only at protein level (Mahé and Grosclaude, 1993;Galliano et al, 2004). Another variant has been found by Chianese et al (2007) at protein level but it was not yet characterised.…”

Genetic testing for phenotype-causing variants in sheep and goats

“…In this method, PCR amplification is followed by a sample denaturation step and electrophoresis [36]. PCR-SSCP protocols for haplotype determination were established for the ovine prion protein [37] and the caprine alpha s1 [38] and beta [39] casein genes. A disadvantage of this method is the need to include standard samples for all expected haplotypes in each run to assure correct genotyping.…”

Quantitative determination of casein genetic variants in goat milk: Application in Girgentana dairy goat breed

“…The allele A at this locus was assigned when all the other alleles were not present. The CSN2 A/A1, C, C1, E, and 0' alleles were identified using PCR protocols of Chessa et al (2005) and Chessa, Rignanese, Küpper, et al (2008), amplifying part of exon 7-intron 8, and exon 8-intron 9, followed by sequencing of amplified fragments with ABI PRISM 3130xl Genetic Analyzer (Applied Biosystems). Moreover, PCR-RFLP protocol proposed by Cosenza, Paciullo, Gallo, Di Berardinno, and Ramunno (2005) was used to discriminate allele A to A1.…”