IGF2 is one of the genes involved in myogenesis. A mutation that increases the level of IGF2 mRNA and affects carcass composition was found in intron 3 of the IGF2 gene (A3072G) (Van Laere et al. 2003). The influence of this mutation on meatiness has been confirmed by other authors in various populations of pigs (Estelle et al. 2005). However, associations between the IGF2 muta- tion and growth performance and meat quality traits are not clear to date. Moreover, to date, there is no data about the influence of IGF2 on intra- muscular fat – an important trait determining the palatability of meat. The aim of our study was to compare body composition, growth performance, and meat quality traits in Polish Landrace and Large White pigs, carrying opposite genotypes (A/A and G/G) in the IGF2 gene. Animals for the study originated from 4 slaughter performance testing stations: Chorzelów, Me³no, Paw³owice, and Rossocha. In total, 267 Large White (LW) and 271 Polish Land- race (PL) gilts were genotyped. The closest rela- tives were half-sisters (the offspring of 140 and 143 sires, respectively). All tested pigs were fed ad libitum. The test began at 30 kg l.w. and was ter- minated at 100±8 kg l.w. The A3072G IGF2 mu- tation was genotyped on 7500 Real-Time PCR System (Applied Biosystems), according to Carrodegous (2005). The C/T RYR1 mutation was J Appl Genet 50(3), 2009, pp. 257–259 Short communication Known mutation (A3072G) in intron 3 of the IGF2 gene is associated with growth and carcass composition in Polish pig breeds M. Oczkowicz 1 , M. Tyra 1 , K. Walinowicz 1 , M. Ró¿ycki 1 , B. Rejduch 2 1 National Research Institute of Animal Production, Department of Animal Genetics and Breeding,Poland 2 National Research Institute of Animal Production, Department of Animal Immuno- and Cytogenetics, Balice, Poland Abstract. IGF2 is one of the genes that control muscle development. Moreover, IGF2 is imprinted, as only the paternal allele is expressed in the offspring. Using real-time PCR for IGF2 genotyping (Carrodegous et al. 2005), we evaluated the frequency of the IGF2 A3072G mutation (Van Laere et al. 2003) in pigs: Polish Landrace (PL, N = 271) and Large White (LW, N = 267). Our results are consistent with previous reports, showing that the A allele is common in breeds subjected to strong selection for lean meat content (A allele frequency was 0.79 in LW and 0.69 in PL). Moreover, we compared body composition, growth performance and meat quality traits in pigs carrying opposite genotypes (A/A and G/G) in the IGF2 gene. The association study revealed that the A allele increases the weight of loin (WL) (additive gene effect = 450±50 g in LW and 213±64g in PL), weight of ham (WH) (544±48 g in LW and 302±72 g in PL), loin eye area (LEA) (4.9±0.46 cm 2 in LW and 2.1 ±0.95 cm 2 in PL), carcass meat percentage (CP) (3.12±0.27% in LW and 1.89±0.47% in PL), and decreases average backfat thick- ness (ABF) (-0.2±0.036 cm in LW and -0.2±0.048 cm in PL). Additionally, in PL, the A allele increases the weight of tenderloin (WT) (11±0.01 g), average daily gain (ADG) (30.7±17.29 g), and decreases feed intake (F) (-121±45 g) and days of feeding (DF) (-3.5±2.08 days). No significant effects were observed for meat quality traits. Our results suggest that selection based on the IGF2 mutation in Poland may be very useful in PL and LW pigs, where the G allele is still relatively frequent. Keywords: carcass composition, growth performance, IGF2, imprinting, mutation, pig. Received: August 20, 2008. Revised: October 4, 2008. Accepted: November 19, 2008. Correspondence: B. Rejduch, National Research Institute of Animal Production, Department of Animal Immuno- and Cytogenetics, Krakowska 1, 32–083 Balice, Poland; e-mail: brejduch@izoo.krakow.pl