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J M Urra

Publications and source records attributed to J M Urra.

8 recordsLinked to original sources
PubMed1991

DNA polymorphisms and linkage relationship of the human complement component C6, C7, and C9 genes.

In this report we describe the linkage between genes encoding human complement components C6, C7, and C9. Polymorphisms have been described at the DNA level for the C7 and C9 genes. We have studied 20 individuals by Southern blot analysis with four C6 cDNA subclones to detect restriction fragment length polymorphisms (RFLPs). We have found a Taq I polymorphism defined by two alleles of 8.0 (C6 H) and 6.0 (C6 L) kilobases (kb). RFLP segregation for the C6, C7, and C9 loci in informative families allowed us to estimate the maximum Lod scores at a recombination fraction of theta = 0.0 (C6-C7), theta = 0.0 (C7-C9), and theta = 0.0 (C6-C9). Significant linkage disequilibrium was found between C6 and C7 and between C7 and C9 loci in directly determined haplotypes of unrelated parents. Data from this study show that the genes encoding the human terminal complement components C6, C7, and C9 define a cluster in the short arm of chromosome 5. We propose that the clusters involving the C8A and C8B and the C6, C7, and C9 genes be referred to as MACI and MACII, respectively.

Chromosome Mapping↗
PubMed1991

DNA analysis of HLA-DR4B1 subtypes in multiple sclerosis by specific oligonucleotide probes.

Conversely to the well-established association of DR2/Dw2 with multiple sclerosis (MS) susceptibility in Caucasoids, several studies have found an association of DR4 in populations from Mediterranean origin. We have studied the distribution of the different DR4B1 subtypes in Spanish MS patients. Oligonucleotide probes were selected in order to type samples amplified by polymerase chain reaction (PCR) from Spanish DR4+ MS patients (25) and controls (28). No DR4B1 subtypes were found to be increased in MS. MS susceptibility linked to DR4 may be due to the presence of shared functional epitopes common to the different HLA-DR4B1 subtypes.

Amino Acid Sequence↗
PubMed1991

Germline repertoire of T-cell receptor beta-chain genes in patients with insulin-dependent diabetes mellitus.

We have investigated the genotype and allelic distribution of germline restriction fragment length polymorphisms of the T-cell receptor beta chain, segment C beta, and two variable segments which are in linkage disequilibrium, V beta 8 and V beta 11, in 42 insulin-dependent diabetes mellitus (IDDM) patients and in 51 healthy blood donors used as controls. Recently, several works have reported contradictory results showing or not showing an association between polymorphic alleles of the C beta gene and diabetes type I. We found no significant differences in the allele, genotype, and haplotype distribution of the gene segments studied, between IDDM patients and control populations.

Adolescent↗