A dinucleotide repeat polymorphism in the human LAMB2 gene on chromosome 1q

Identification of a gene that causes primary open angle glaucoma

Glaucoma is a major cause of blindness and is characterized by progressive degeneration of the optic nerve and is usually associated with elevated intraocular pressure. Analyses of sequence tagged site (STS) content and haplotype sharing between families affected with chromosome 1q-linked open angle glaucoma (GLC1A) were used to prioritize candidate genes for mutation screening. A gene encoding a trabecular meshwork protein (TIGR) mapped to the narrowest disease interval by STS content and radiation hybrid mapping. Thirteen glaucoma patients were found to have one of three mutations in this gene (3.9 percent of the population studied). One of these mutations was also found in a control individual (0.2 percent). Identification of these mutations will aid in early diagnosis, which is essential for optimal application of existing therapies.

A partial hydatidiform mole with 2N/3N mosaicism identified by molecular analysis

PURPOSE

A placenta with a partial hydatidiform mole was studied using DNA polymorphic markers to determine whether it has a triploid cell line.

METHOD

Parent-mole transmission of alleles at 23 polymorphic loci was traced in cells from a molar region and a normal-looking region of the placenta by polymerase chain reaction (PCR) amplification or Southern blot analysis, both followed by densitometric analysis.

RESULTS

Allele patterns for 8 of the 23 loci were identical between the DNA from the molar and normal regions of the placenta, while those of the remaining 15 loci were uninformative. In the molar region, the band intensity for the paternally derived allele at each informative locus was always greater than that of the maternally derived allele, the average intensity ratio of the former to the latter being 1.5, whereas the ratio in the normal region was even.

CONCLUSIONS

The results suggested that the molar region was a mixoploid consisting of diploid and triploid cells and the phenotypically normal region had a mainly diploid constitution. It is most likely that the placenta may have originated from a single diploid or triploid conceptus, followed by postzygotic gain or loss of a paternal haploid set, and that an extra paternal set contributed to hydropic changes of the placenta.

Fine mapping of the autosomal dominant juvenile open angle glaucoma (GLC1A) region and evaluation of candidate genes

Juvenile Open Angle Glaucoma (GLC1A) is an autosomal optic neuropathy that has been localized previously to chromosome 1q. Here we report the fine mapping of the disease region using YACs and a high density of polymorphic microsatellite markers. This study utilized two large JOAG pedigrees genotyped at 36 loci from chromosome 1q21-q31 to refine the GLC1A locus to a approximately 3-cM region flanked by YAC-derived microsatellite markers D1S3665 and D1S3664. The candidate genes LAMC1, NPR1, and CNR2 were excluded from the region by linkage. Four other genes, SELE, SELL, TXGP1, and APT1LG1, were determined to lie within the critical region through YAC content and linkage mapping. The YAC-STS content map of the critical region provides the groundwork for the construction of a transcription map and the identification of the disease-causing gene.