Association Analysis Between DNA Markers and Number of Functional Teats in Italian Large White Pigs - Veterinary Science - page 183

30.3 Results

An association study between five polymorphisms located in different genes
(Table 30.1 ) and FTNUM was carried out. All polymorphisms segregated in
ITLW. Minor allele frequency (MAF, Table 30.2 ) ranged from 0.18 (allele
AJ315771:g.5325 T of CTSL and allele EU4077778:g.2373 T of EPOR genes) to
0.40 (allele AF164957:c.949 G of the ESR2 gene). As genetic markers were
informative (Table 30.2 ), it was possible to perform an association study with
FTNUM. Considering the entire analyzed population, the mean and standard
deviation of these traits were equal to 14.57

0.76. In particular, 59% of sows
had 14 FTNUM (group 1), and the remaining 41% had 15-17 FTNUM (group 2).
The sows of the two groups had similar inbreeding mean values and years of birth
(between 2002 and 2007). The classification of the sows into two groups made it
possible to apply a statistical analysis to the categorical variables. Table 30.2
reports MAF in the entire sample and in the two groups of sows for the five
analyzed polymorphisms. All SNPs were in Hardy-Weinberg equilibrium in both
groups of sows ( P 0.05). The CTSL , EPOR , ESR2 , and STAT5B marker genes

were not associated with FTNUM. A statistically significant difference of allele

>

Table 30.1 Details of the analyzed polymorphisms and references
Gene name,
symbol

Accession number:
polymorphism

Chromosome, gene
region, amino acid
change

References

Cathepsin L, CTSL AJ315771:

g.5325 C > T

10, exon 5, silent Fontanesi et al. ( 2010 )

Erythropoietin receptor,
EPOR

EU4077778:
g.2373 C > T

2, intron 4 Vallet et al. ( 2005 )

Estrogen receptor 2, ESR2 AF164957:

c.949 G > A

1, exon 5, p.V317M Mu˜oz et al. ( 2004 )

Glutathione peroxidase 5,
GPX5

AF124818:
g.1939 C > T

7, 3 0 -UTR Bertani et al. ( 1999 )

Signal transducer and
activator of transcription
5B, STAT5B

DQ144238:
g.191A > G

12, intron 14 Ballester et al. ( 2006 )

Table 30.2 Minor allele frequency (MAF) of the polymorphisms analyzed in the entire sample
and in the two groups of sows based on their teat number
Genes

No. of
analyzed
sows

MAF -
entire data
set

MAF - Group 1
FTNUM ¼ 14

MAF - Group 2
FTNUM > 14

Allele frequency
difference 1 vs. 2, P a

CTSL 1,086 0.18 (T) 0.18 0.19 0.7112

EPOR 1,027 0.18 (T) 0.17 0.19 0.1236

ESR2 1,094 0.40 (G) 0.40 0.41 0.5686

GPX5 940 0.36 (T) 0.34 0.40 0.0087

STAT5B 1,091 0.20 (G) 0.20 0.21 0.5528

a Probability of the comparison ( P )