Assignment of the locus for arachnomelia syndrome to bovine chromosome 23 in Simmental cattle.

Arachnomelia syndrome is a lethal inherited malformation mainly of the limbs, vertebral column and skull in cattle, which poses a severe impairment to farmers and breeders. Recently, a number of cases of arachnomelia syndrome have occurred in the Simmental breed and some sires with excellent breeding values had been shown to be carriers of the disease. We herein report the genetic mapping of the mutation underlying arachnomelia in cattle. The disease was mapped using a two-stage genome scan. A first round autosomal genome-wide screening using a limited number of cases identified three chromosomal regions with lod-scores > 1. The position of the arachnomelia syndrome locus was identified to be on BTA 23 by genotyping an additional, independent set of animals with markers that provided positive lod-scores in the course of the initial genome-wide screen. Using a denser set of regional microsatellites, the locus could be mapped to a region about 9 cM in length. The most significant linkage signal with arachnomelia syndrome was obtained with marker NRKM-17 (lod-score > 20) using a recessive model. Interestingly, different genes seem to be responsible for the disease in Brown Swiss and Simmental breeds, as arachnomelia syndrome was mapped to a different location in Brown Swiss. The results provide sufficient information for the development of a genetic test system and also allow the identification of positional candidate genes.

Amniotic fluid phosphatidylglycerol: a predictor of fetal lung maturity using conventional one-dimensional thin-layer chromatography.

We present a retrospective comparative analysis of 209 amniotic fluid samples and the neonatal outcome. The presence of phosphatidylglycerol in 159 transabdominal amniotic fluid samples and the associated lung status indicated a 98% prediction rate for absence of respiratory distress syndrome with 1.8% false-positive results corrected to 0%. Twenty-nine vaginal pool samples were 72% predictive of outcome with false-positive results corrected to 14%. These cases were mild, and if a phosphatidylglycerol level of greater than 3% is used to indicate lung maturity, the corrected false-positive rate is 0%. False-negative results are also corrected and discussed. We believe that predicting neonatal respiratory distress syndrome by phosphatidylglycerol determination, using readily available conventional one-dimensional thin-layer chromatography, is clinically reliable and can aid in determining the maturity of the lung regardless of site of fluid collection.