Williams syndrome (WS) is a developmental disorder affecting connective tissue and the central nervous system. A common feature of WS, supravalvular aortic stenosis, is also a distinct autosomal dominant disorder caused by mutations in the elastin gene. In this study, we identified hemizygosity at the elastin locus using genetic analyses in four familial and five sporadic cases of WS. Fluorescent in situ hybridization and quantitative Southern analyses confirmed these findings, demonstrating inherited and de novo deletions of the elastin gene. These data indicate that deletions involving one elastin allele cause WS and implicate elastin hemizygosity in the pathogenesis of the disease.

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Pedigree and early performance records from lambs on three New Zealand research stations, involving 51 station-years of data (55 146 recorded lambs born), were analysed in order to study genetic and environmental factors affecting perinatal and preweaning survival. Mean birth weights at each site were very similar, being 4.26 kg at Woodlands, 4.22 kg at Tokanui, and 4.32 kg at Rotomahana Station. Total survival rates to weaning (preweaning survival) across sites averaged 79.0, 78.9, and 80.1%, respectively. Analyses of variance for perinatal survival and preweaning survival showed significant effects of contemporary group of lamb, age of dam, and birth rank-sex combinations, whilst linear and curvilinear effects of birth weight were also significant. Optimal birth weights were 4.36 kg and 4.77 kg for maximal perinatal survival and maximal preweaning survival, respectively. Heavy singles and twins were at higher risk of not surviving, but light singles and twins were also at risk. At birth, survival was consistently lowest from lambs out of 2-year-old dams, whilst preweaning survival was lower amongst lambs from 2-and 5-year-old dams, and higher in lambs from 3-and 4-year-old dams.Estimates of total heritability (direct + maternal + direct-maternal covariance) for perinatal survival as a transformed (logit) trait were 0.055 (Tokanui and Woodlands data), and 0.105 (Rotomahana data). A00029 Received 7 June 2000; accepted 31 August 2000Corresponding estimates for preweaning survival were 0.031 and 0.101, respectively. Maternal genetic variances for perinatal and preweaning survival as logit traits were 1.5-5 times the size of the lamb's additive genetic variance. Our analyses confirm previous low genetic parameter estimates for lamb survival.

A selection experiment to change reproductive traits in Angus cattle has been maintained for 14 years, with first calvings in 1985. Alongside an unselected control line, three lines were established, selected for increased age at puberty in heifers (AGE+ line), reduced age at puberty in heifers (AGE-line), or increased scrotal circumference (SC line). The last two lines were merged at the 1992 matings, with the revised objective of applying further selection in both sexes to reduce age at puberty in heifers. Dates at puberty in heifers from an average of 8 to 16 months of age and SC in bulls were recorded in all lines, along with the pregnancy rates (PR) and subsequent calving dates (CD) in heifers and all cow-age groups. Heritabilities of single-record SC, standardised age at first behavioural oestrus (SFO), and single-record CD were 0.41 ± 0.04 (repeatability 0.70 ± 0.01), 0.27 ± 0.04, and 0.09 ± 0.04 (repeatability 0.19 ±0.03), respectively. Genetic correlations of SC with SFO and CD were -0.25 ± 0.09 and -0.23 ± 0.15, respectively; SFO with CD 0.57 ± 0.17; and PR with SFO and SC-0.36 ±0.13 and 0.12 ± 0.11, respectively. The selection-line difference in PR over seven years (AGE-mean minus AGE+ mean), excluding yearling heifer matings, was 4.7 ± 2.1% (P < 0.05). Mean CD in the AGE-line was 3 days earlier than in the AGE+ line (P < 0.09). These correlation and selection-line results suggest that selecting for higher SC and earlier heifer puberty leads to earlier CD and higher PR.