High specificity PCR screening for 22q11.2 microdeletion in three different ethnic groups

Congenital heart defects are the most common of all human birth defects. Numerous studies have shown that a deletion within chromosome 22q11 is associated with DiGeorge syndrome and certain forms of sporadic congenital cardiovascular disease. We have determined the value of a PCR assay using markers D22S941, D22S944 and D22S264 designed for the screening of 22q11.2 deletion through consecutive homozygosity in an ethnically admixed urban population. The study population comprised 149 unrelated men and women from three different ethnic groups (white, mulatto and black). Test specificity for the overall population was estimated at 98.3 percent. We found no significant difference when comparing heterozygosity indices and ethnicity (P value = 0.43 (D22S944), 0.22 (D22S264), and 0.58 (D22S941)). There was no significant difference regarding assay specificity between the three different ethnic groups studied. This assay could constitute a cost-effective way to screen a large number of patients at increased risk, since PCR techniques are easily available, are fast, can be automatized, and are significantly less expensive than fluorescence in situ hybridization

Evolutionary conservation of laminin-binding proteins

The virulence of pathogens and metastatic capacity of cancer cells seems to correlate with the ability to adhere to cells and/or to basement components. A key feature of this mechanism in the expression of specific receptors for the basement membrane protein laminin. There different receptors have been already described in cells phylogenetically very distant, such as human white blood cells, Trichomonas vaginalis and Stapgylococcus aureus, all recognizing laminin with the same range of affinity. We have shown that laminin, which is also found in the circulation, enchances phagocytosis of S. aureus by macrophages in a species-specific fashion. Also, monoclonal antibodies (MAb) raised against the bacterial receptor inhibit the phagocytic enhancement mediated by laminin and recognize laminin-binding proteins in unicellular parasites and mammalian cells. The same Mab 1.H12 elutes a 52-kDa protein from bacterial extracts and a 67-kDa band from cancer cells extracts. Since the MAb is a monospecific reagent, results with 1.H12 strongly suggest and evolutionary conservation of the biding site of phylogenetically different laminin receptors