Linkage mapping of the locus responsible for congenital multiple ocular defects in cattle on bovine Chromosome 18

Congenital cataracts in an Ayrshire herd: a herd case report

An Ayrshire dairy herd was investigated for occurrence of ocular abnormalities in new-born calves. Ophthalmic examinations were performed on all the animals in the herd and 26% of them were diagnosed with bilateral cataracts. Cataracts varied in extent and severity but the majority were restricted to the lens nucleus. Epidemiological analysis showed the prevalence was higher in male animals and lower in animals born to heifers. A family tree was designed but no genetic impact of dam lines was evident. Sire data was incomplete and could therefore not be included. Based on the information provided by the farmer there was no obvious environmental or nutritional cause of these cataracts. However, data records were incomplete and further investigation/monitoring of the herd would be needed to establish a cause and enable a better insight into the aetiology of this disease in cattle.

Exclusion of NEU1 and PPGB from candidate genes for a lysosomal storage disease in Japanese Black cattle

A case of lysosomal storage disease has been reported in a calf of Japanese Black cattle. Lysosomal storage diseases are hereditary diseases caused by deficiency of lysosomal hydrolases. The clinical and pathological features and accumulated substrates of the affected animal indicated a possibility of sialidosis or galactosialidosis caused by deficiency of neuraminidase (NEU1) or protective protein for beta-galactosidase (PPGB). In the present study, we investigated nucleotide sequences of the genes encoding these two proteins to evaluate whether mutation of these genes is involved in this disease. We determined cattle genomic sequences of these two genes by using bovine EST sequences and the nucleotide sequences of all exons of these genes were compared between affected and normal animals. The results showed several nucleotide substitutions, but none of them was a functional mutation or specific to the affected animal. Furthermore, genotyping of the microsatellite markers in the vicinity of these two genes revealed no homozygosity of the chromosomal regions including these genes in the affected animal. These findings indicated that neither NEU1 nor PPGB gene is responsible for the lysosomal storage disease of Japanese Black cattle and therefore the disease is neither sialidosis nor galactosialidosis.

Linkage mapping of the locus responsible for forelimb-girdle muscular anomaly of Japanese black cattle on bovine chromosome 26

Forelimb-girdle muscular anomaly is an autosomal recessive disorder of Japanese black cattle characterized by tremor, astasia and abnormal shape of the shoulders. Pathological examination of affected animals reveals hypoplasia of forelimb-girdle muscles with reduced diameter of muscle fibres. To identify the gene responsible for this disorder, we performed linkage mapping of the disorder locus using an inbred pedigree including a great-grand sire, a grand sire, a sire and 26 affected calves obtained from a herd of Japanese black cattle. Two hundred and fifty-eight microsatellite markers distributed across the genome were genotyped across the pedigree. Four markers on the middle region of bovine chromosome 26 showed significant linkage with the disorder locus. Haplotype analysis using additional markers in this region refined the critical region of the disorder locus to a 3.5-Mb interval on BTA26 between BM4505 and MOK2602. Comparative mapping data revealed several potential candidate genes for the disorder, including NRAP, PDZD8 and HSPA12A, which are associated with muscular function.