Mordechai Mizrachi-Koren

Bethlehem University, Bayt Laḩm, West Bank, Palestinian Territory

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Publications (3)17.29 Total impact

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    ABSTRACT: The routine diagnosis of genodermatoses is significantly complicated by the fact that in this group of disorders, clinical manifestations may result from mutations in unrelated genes (genetic heterogeneity) and mutations in the same gene often lead to dissimilar clinical signs (phenotypic heterogeneity). In this study, we applied the principles of homozygosity mapping as a screening method before formal mutational analysis in an attempt to facilitate the molecular diagnosis of genodermatoses in consanguineous families. The method was evaluated in a retrospective fashion in 4 families previously assessed with junctional epidermolysis bullosa and in a prospective manner in 11 families with congenital recessive ichthyosis. The method was found to be efficient in directing the molecular analysis to one of the 4 genes commonly involved in the pathogenesis of junctional epidermolysis bullosa or in identifying cases of congenital recessive ichthyosis caused by mutations in TGM1. We found that this diagnostic strategy results in a 5-fold decrease in the cost of mutation analysis. The proposed diagnostic strategy is applicable to consanguineous families only and, therefore, cannot be used in outbred populations. Our results indicate that homozygosity mapping may serve as a useful adjunct in the molecular diagnosis of junctional epidermolysis bullosa or congenital recessive ichthyosis in inbred populations. This study emphasizes the usefulness in human genetics of diagnostic strategies tailored to the demographic features of target populations.
    Journal of the American Academy of Dermatology 10/2006; 55(3):393-401. · 4.91 Impact Factor
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    ABSTRACT: Epidermolysis bullosa (EB) encompasses a large group of inherited blistering skin disorders caused by mutations in at least 10 genes. Numerous studies, mainly performed in European and US families with EB, have revealed a number of characteristic epidemiological and genetic features, which form the basis for current diagnostic and counseling strategies. However, little is currently known about the molecular epidemiology of EB in Middle East populations. In the present study, we assessed 55 EB families for pathogenic sequence alterations in the 10 genes known to be associated with EB. Our results show unique EB subtype distribution and patterns of inheritance in our cohort. We also failed to detect recurrent mutations frequently encountered in Europe and the US, and did not consistently observe genotype-phenotype correlations formerly established in Western populations. Thus, the molecular epidemiology of EB in the Middle East is significantly different from that previously delineated in Europe and the US. Our data raise the possibility that similar differences may also be found in other genetically heterogeneous groups of disorders, and indicate the need for population-specific diagnostic and management approaches.
    Journal of Investigative Dermatology 05/2006; 126(4):777-81. · 6.19 Impact Factor
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    ABSTRACT: Congenital recessive ichthyoses represent a vast and markedly heterogeneous group of diseases that have been mapped to at least seven distinct chromosomal loci. In this study, we ascertained two consanguineous families presenting with congenital ichthyosis. Using homozygosity mapping, we identified a 6.5 cM homozygous region on 12p11.2-q13 shared by all affected individuals. Multipoint logarithm of odds ratio (LOD) score analysis placed the new locus between markers D12S345 and D12S390 with a maximum LOD score of 4.79 at marker CH12SSR13. This region harbors PPHLN1, encoding periphilin 1, a protein involved in the cornification process. No deleterious mutations were identified within the coding region of this gene, suggesting the existence of another gene associated with epidermal differentiation on 12p11.2-q13.
    Journal of Investigative Dermatology 10/2005; 125(3):456-62. · 6.19 Impact Factor