Localization of a gene for otosclerosis to chromosome 15q25-q26

Among white adults otosclerosis is the single most common cause of hearing impairment. Although the genetics of this disease are controversial, the majority of studies indicate autosomal dominant inheritance with reduced penetrance. We studied a large multi- generational family in which otosclerosis has been inherited in an autosomal dominant pattern. Five of16 affected persons have surgically confirmed otosclerosis; the remaining nine have a conductive hearing loss but have not undergone corrective surgery. To locate the disease- causing gene we completed genetic linkage analysis using short tandem repeat polymorphisms (STRPs) distributed over the entire genome. Multipoint linkage analysis showed that only one genomic region, on chromosome 15q, generated a lod score >2.0. Additional STRPs were typed in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis gene.      

Detection of gene amplification in archival breast cancer specimens by laser-assisted microdissection and quantitative real-time polymerase chain reaction

Gene amplification is one of the most important mechanisms leading to deregulated gene expression in cancer. The exact quantitative detection of this frequent genomic alteration in solid tumors is often hampered by an admixture of nonneoplastic bystander and stroma cells. To overcome this obstacle and to develop an objective quantitative method we have combined laser-assisted microdissection of tumor cells with the novel 5'-exonuclease-based real-time polymerase chain reaction (PCR) assay. The latter method enables the highly reproducible exact quantification of minute amounts of nucleic acids. As a model system amplification of c-erbB2/Her-2/neu gene and the adjacent topoisomerase IIalpha gene was determined in paraffin-embedded breast cancer specimens (n = 23) after immunohistochemical labeling and laser-based microdissection of tumor cells. The high sensitivity of real-time PCR enabled the reliable and objective detection of low-level amplifications in as few as 50 cells from archival tissue sections. Low-level amplifications were shown to escape from detection unless tumor cells were isolated by microdissection. In selected cases intratumor heterogeneity was demonstrated using areas of approximately 50 to 100 cells. This novel approach combining immunohistochemistry, laser microdissection, and quantitative kinetic PCR allows morphology-guided studies in archival tissue specimens and will enable the exact quantification of gene copy numbers in even small and precancerous lesions.     

Ligamentary structure of the base of the nail

Summary The authors report the results of 115 dissections of the base of the distal phalanx of fingers and toes. In 85% of cases including hypoplastic supernumerary digits, there is a connective ligament-like structure. It is a dorsal expansion of the lateral ligament of the distal inter-phalangeal joint arising from the intermediate phalanx and ending in the matrix and the lunula. This ligament may have a role in biomechanical strains on the nail. It can explain some dystrophic nails associated with some malpositioned joints in fingers or toes.

---

Structure ligamentaire de la base de l'ongle

Résumé Les auteurs rapportent les résultats de 115 dissections portant sur la base de la phalange distale des doigts ou des orteils. Ils retrouvent dans 85 % des cas, y compris sur des doigts hypoplasiques surnuméraires, une formation conjonctive de type ligamentaire. Il s'agit d'une expansion dorsale du ligament latéral de l'articulation interphalangienne distale, naissant de l'extrémité distale de la phalange intermédiaire et se terminant au sein de la matrice et sur la lunule. Ce ligament ostéomatriciel peut jouer un rôle dans la transmission des contraintes biomécaniques sur l'ongle et expliquer les dystrophies unguéales stéréotypées associées à certaines malpositions articulaires des doigts ou des orteils.