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In the HLA-G locus, the 3'-untranslated region (3'-UTR) begins in the mid exon 6, and ends in exon 8. The occurrence of a 14-bp deletion within exon 8, the only mutation known until now in the 3'-UTR, has been considered a risk factor for disease and allograft rejection. To describe the polymorphism within this region, direct sequencing analysis was performed on 120 DNA samples from Portugal and Guinea-Bissau. Results indicate that exon 8 is less conserved than the coding exons. Nine single nucleotide polymorphisms and the previously described 14-bp deletion were found within exon 8 of both populations. Molecular diversity was higher in the Guinean samples than in the Portuguese; however, little differentiation was found among the populations, suggesting that local selection on exon 8 sequence variation is absent. The screening for sequence motifs suggests that polymorphism on this region may be involved in HLA-G post-transcriptional regulation and, therefore, in phenotype variation.

Idiopathic scoliosis (IS) is the most common spinal deformity in children, and its etiology is unknown. To refine the search for genes underlying IS susceptibility, we ascertained a new cohort of 52 families and conducted a follow-up study of genomewide scans that produced evidence of linkage and association with 8q12 loci (multipoint LOD 2.77; P=.0028). Further fine mapping in the region revealed significant evidence of disease-associated haplotypes (P1.0 x 10-4) centering over exons 2-4 of the CHD7 gene associated with the CHARGE (coloboma of the eye, heart defects, atresia of the choanae, retardation of growth and/or development, genital and/or urinary abnormalities, and ear abnormalities and deafness) syndrome of multiple developmental anomalies. Resequencing CHD7 exons and conserved intronic sequence blocks excluded coding changes but revealed at least one potentially functional polymorphism that is overtransmitted (P=.005) to affected offspring and predicts disruption of a caudal-type (cdx) transcription-factor binding site. Our results identify the first gene associated with IS susceptibility and suggest etiological overlap between the rare, early-onset CHARGE syndrome and common, later-onset IS.

VNTR regions are informative genetic markers for linkage mapping and individual identification. Using PCR, we have developed a procedure for the enzymatic amplification of the VNTR located in the 16th intron of the human retinoblastoma (RB1) gene. We have also prepared a nonisotopically labeled oligonucleotide probe which facilitates detection of the amplification products. In examining 250 individuals from four different populations, we have detected 11 alleles ranging from 650 to 1,800 bp in size. The core repeat is approximately 50 bp in length. On the basis of the observed allele frequencies for Caucasian, African-American, and Hispanic populations from the United States and for the Mexican Hispanic population, the heterozygosities have been calculated to be 62%, 75%, 61%, and 50%, respectively. The observed genotype frequencies do not deviate from the values expected under Hardy-Weinberg equilibrium. The effect of varying primer sequences, annealing temperature, and cycle number on the amplification are also discussed. Amplification of this marker may also prove useful for detecting the heterozygosity loss that is associated with tumor formation in retinoblastoma.

The immunoglobulin kappa light chain (IgK) locus may play a significant role in the pathology of both infectious and autoimmune diseases. Most of the work on IgK genetics has been conducted using immunological techniques for allelic typing and sequence analysis. This is restricted by availability of reagents and can be both expensive and time-consuming. PCR primers were designed to amplify the kappa constant gene (Ck), and four allele-specific oligonucleotides (ASOs) were used to distinguish the alleles in the amplified PCR products. Direct sequencing of PCR products was performed to confirm that the primers specifically amplified the Ck region and the ASOs differentiated the Km alleles. Sequencing of an average of 209 nucleotides of DNA from 50 individuals revealed no variation except at codon 191, which is known to be involved in a frequent polymorphism. An analysis of 347 different individual DNAs from 10 human populations was conducted to determine Km allelic frequencies within these populations and to apply this type of data collection to population studies.

Chromosome 13q has been suggested as the site of a gene predisposing to human breast cancer, because loss of heterozygosity of alleles on this chromosome has been observed in some ductal breast tumors and because two breast cancer lines are altered at the retinoblastoma gene (RB1) at 13q14. To test this possibility, linkage of breast cancer susceptibility to 14 loci on chromosome 13q loci was assessed in extended families in which breast cancer is apparently inherited as an autosomal dominant trait. RB1 was excluded as the site of a breast cancer gene by a lod score of Z = -7.60 at close linkage for 13 families. Multipoint analysis yielded negative lod scores throughout the region between 13q12 and 13q34; over most of this distance, Z less than -2.0. Therefore, chromosome 13q appears to be excluded as the site of primary lesion for breast cancer in these families. In addition, comparison of tumor versus normal tissues of nonfamilial breast cancer patients revealed an alteration at the 5' end of RB1 in a mucoid carcinoma but no alterations of RB1 in five informative ductal adenocarcinomas. Linkage data and comparisons of tumor and normal tissues suggest that changes in the RBI locus either are secondary alterations associated with progression of some tumors or occur by chance.