Hej
Jag var i kontakt med Allan Simonsson på SLU för ett par år sedan om just denna fråga. Bifogar hans svar till mig.
Mvh Denny
"Hej Denny!
Medfödda missbildningar har både en ärftlig och en miljömässig bakgrund. Jag bifogar ett utdrag av en artikel som handlar om arvets betydelse för olika missbildningar. Som Du kan se skattas arvbarheten för tvekönthet (intersexuality) till ca 0.3. D.v.s miljöinflytandet är dubbelt så stort som arvet. Hur vanligt denna missbildning uppträder har jag ingen tillgänglig siffra på.
Med hälsning
Allan
Analysis of genetic parameters for congenital anomalies in the pig breeds German Landrace and Pietrain in Bavaria - 2nd communication: Estimation of genetic parameters using animal models
Beissner B, Hamann H, Distl O
ZUCHTUNGSKUNDE
75 (4): 239-248 JUL-AUG 2003
Abstract:
The objective of the analysis was to estimate heritabilities, additive genetic and residual correlations for the congenital anomalies atresia ani, scrotal and umbilical hernia, cryptorchidism, intersexuality, congenital tremor, splayleg and other congenital anomalies using univariate and multivariate animals models with REML. The analysis was based on data collected from 1982 to 2001. The investigation included the records of 47,200 litters from 340 boars of the breed German Landrace (DL) and 1, 118 boars of the breed Pietrain (PI). The model used included the fixed effects of AI-station, classes of birth years of the AI-boar, the total number of litters tested per AI-boar, the average litter size per AI-boar and the random additive-genetic effect of the AI-boar. A very high heritability of h(2) = 0,82 was estimated for atresia ani in German Landrace boars. For scrotal hernia, cryptorchidism, intersexuality, congenital tremor and splayleg, heritability estimates were moderate between h(2) = 0.22 and 0.35. The heritability estimates for hernia umbilicalis and other anomalies were about h(2) = 0,10. Moderate heritabilities in the range of h(2) = 0.25 to 0.37 were estimated for hernia scrotalis, splayleg and other anomalies in progeny of Pietrain boars. The heritability estimates for atresia ani, hernia umbilicalis and congenital tremor were low (h(2) < 0.10). A high additive genetic correlation was found between hernia umbilicalis and intersexuality in DL. Atresia ani and congental tremor were genetically highly but negatively correlated. Cryptorchidism and hernia umbilicalis, hernia scrotalis, intersexuality and other anomalies were genetically negatively correlated in DL. Highly negative additive genetic correlations were present between hernia umbilicalis and intersexuality as well as between cryptorchidism and other anomalies in PI. A very high additive genetic correlation was found between hernia umbilicalis and congenital tremor (r(g) = 0,71). Additive genetic correlations between atresia am and hernia scrotalis (r(g) = 0.31), hernia scrotalis and cryptorchidism (r(g) = 0.12) as well as atresia ani and cryptorchidism (r(g) = -0.17) were low to moderate and some of them were even negative. The additive genetic correlations between hernia umbilicalis and hernia scrotalis, intersexuality and congenital tremor as well as between atresia ani and other anomalies were not consistent between the breeds DL and PI. Highly negative additive genetic correlations were found for both breeds between cryptorchidism and other anomalies and between intersexuality and congenital tremor. Both breeds showed moderate additive genetic correlations between intersexuality and atresia ani."
