Our aim is to assess the heritability of biometric ocular traits and to perform a genome wide scan to identify the associated QTLs. This study was conducted in Talana, an isolated village in eastern Sardinia whose demographic history exhibits ancient origin, low number of founders, high inbreeding and genealogical trees reconstructable from 1640. Volunteers from Talana (N=789, aged 5-89 years) have undergone a complete eye examination including ocular biometry: axial length (AL), anterior chamber depth (ACD) and corneal curvature (CC) were measured. Heritability analysis was performed by means of two methods: parent-offspring regression models on 201 nuclear families and variance component models on 3-4 generations pedigrees. Two and multipoint linkage analysis were performed using 654 microsatellites. The heritability estimates obtained by means of parent offspring regressions and variance components were consistent and significant (p<0.05). CC (mean value 7.67 ± 0.25) had an heritability estimate of 62%. AL (mean value 23.49 ± 0.91) and ACD (mean value 3.45 ± 0.34) were found to have significantly different variances (P<0.01) in males and females so that heritability had to be calculated separately for each sex in the parent offspring regression models. AL had an estimated heritability in females of 31% and in males of 60%, whereas ACD had an estimated heritability in females of 47% and of 44% in males. Suggestive evidences of linkage in multipoint analysis were identified on chromosomes 6, 7, 14 and 15 for ACD, on chromosomes 6 and 12 for CC and on chromosome 2 for AL. To further examine the observed differences in parental transmission we performed Haseman Elston regressions, extended to accommodate parent of origin effects, on a broader sample of 231 nuclear families for markers with evidence of linkage. Preliminary results for AL suggest a preferentially paternal expression. Later findings on all morphometric traits will be discussed.
Heritability and identification of quantitative traits loci in eye morphometry: evidence of imprinting
G Biino;M Pirastu
2003
Abstract
Our aim is to assess the heritability of biometric ocular traits and to perform a genome wide scan to identify the associated QTLs. This study was conducted in Talana, an isolated village in eastern Sardinia whose demographic history exhibits ancient origin, low number of founders, high inbreeding and genealogical trees reconstructable from 1640. Volunteers from Talana (N=789, aged 5-89 years) have undergone a complete eye examination including ocular biometry: axial length (AL), anterior chamber depth (ACD) and corneal curvature (CC) were measured. Heritability analysis was performed by means of two methods: parent-offspring regression models on 201 nuclear families and variance component models on 3-4 generations pedigrees. Two and multipoint linkage analysis were performed using 654 microsatellites. The heritability estimates obtained by means of parent offspring regressions and variance components were consistent and significant (p<0.05). CC (mean value 7.67 ± 0.25) had an heritability estimate of 62%. AL (mean value 23.49 ± 0.91) and ACD (mean value 3.45 ± 0.34) were found to have significantly different variances (P<0.01) in males and females so that heritability had to be calculated separately for each sex in the parent offspring regression models. AL had an estimated heritability in females of 31% and in males of 60%, whereas ACD had an estimated heritability in females of 47% and of 44% in males. Suggestive evidences of linkage in multipoint analysis were identified on chromosomes 6, 7, 14 and 15 for ACD, on chromosomes 6 and 12 for CC and on chromosome 2 for AL. To further examine the observed differences in parental transmission we performed Haseman Elston regressions, extended to accommodate parent of origin effects, on a broader sample of 231 nuclear families for markers with evidence of linkage. Preliminary results for AL suggest a preferentially paternal expression. Later findings on all morphometric traits will be discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.