Abstract: The acid .beta.-galactosidase cDNA of Portuguese Water (PW) dogs was isolated and sequenced. The entire encoding region of the gene consists of 2004 nucleotides coding a protein of 668 amino acids. Its encoding sequence indicates approximately 86.5% identity at the nucleotide level and about 81% identity at the amino acid level with the encoding region of the human acid .beta.-galactosidase gene. The deduced amino acid sequence contains a 24-amino acid putative signal sequence, 6 possible glycosylation sites, and 7 cysteine residues. A homozygous recessive mutation, causing G.sub.M1 -gangliosidosis in PW dogs, was identified at nucleotide G.sup.200 .fwdarw.A in exon 2 resulting in an Arg.sup.60 .fwdarw.His (mutation R60H) amino acid substitution. The mutation creates a new restriction enzyme site for PmlI. Genotyping 115 dog samples for this acid .beta.-galactosidase gene alteration readily distinguished affected homozygous recessive (n=5), heterozygous carriers (n=50), and normal homozygotes (n=60).

Abstract: A method for screening for, diagnosing, monitoring or staging of multiple sclerosis, HIV infection, rheumatoid arthritis or systemic lupus erythematosus in a subject, is based on the detection of IgG antibodies against the hydroxy-fatty acid form of sulfatide in a tissue or body fluid sample of the subject. The presence of such IgG levels substantially above those in healthy controls is indicative of an increased likelihood that the subject has one of such conditions.