Germline fumarate hydratase mutations and evidence for a founder mutation underlying multiple cutaneous and uterine leiomyomata.

Multiple cutaneous and uterine leiomyomata syndrome (MCL) is an autosomal dominant disease characterized by the presence of concurrent benign tumors of smooth muscle origin (leiomyoma) in the skin and uterus of affected females, and in the skin of affected males. MCL can also be associated with type II papillary renal cell cancer (HLRCC). The genetic locus for MCL and HLRCC was recently mapped to chromosome 1q42.3-43 and subsequently, dominantly inherited mutations in the fumarate hydratase gene ( FH ) were identified. Importantly, analysis of the FH gene in tumors of MCL patients revealed a second mutation inactivating the wild-type allele in some tumors. Based on these findings, it has been suggested that FH may function as a tumor suppressor gene in MCL. Here, we report the analysis of the FH gene in a group of 11 MCL families, with the identification of 8 different mutations accounting for the disease in all families. One of the mutations, 905-1G>A, has been identified in 4 families of Iranian origin. The analysis of highly polymorphic markers in the vicinity of the FH gene showed a shared haplotype in these 4 families, suggesting that 905-1G>A represents a founder mutation. Collectively, identification of 5 novel and 3 recurrent mutations further supports the role of FH in the pathogenesis of MCL.

Recapitulation of the hairless mouse phenotype using catalytic oligonucleotides: implications for permanent hair removal.

Ribozyme technology is widely used to target mRNA in a sequence-specific fashion and thus change the expression pattern of cells or tissues. While the goal of mRNA targeting is usually the cleavage of mutant mRNAs with the prospect of gene therapy for inherited diseases, in certain instances, targeting of wild-type genes can be used therapeutically. Lack of expression of the mouse hairless gene due to inherited mutations leads to the complete and irreversible loss of hair known as atrichia. We designed this study to recapitulate the hairless phenotype in a restricted manner by topical application of deoxyribozyme-targeting molecules to specifically cleave the mouse hairless mRNA. Histological samples taken from treated skin at different times demonstrated a decreased number of hair follicles, an involution of the remaining follicles, a separation of the dermal papillae, and the presence of dermal cysts, all characteristics of the hairless phenotype, but not normally present in the skin of C57Bl/6 J mice. In this study, we successfully recapitulated the hairless phenotype using topically applied target-specific catalytic oligonucleotides designed to cleave the mouse hairless mRNA. Our results demonstrate the feasibility of using ribozyme technology to alter the gene expression in the skin via topical application and provide proof of principle for the development of this strategy for permanent hair removal.

Paternal germline mosaicism in Herlitz junctional epidermolysis bullosa.

We studied a single patient with the lethal (Herlitz) type of junctional epidermolysis bullosa (H-JEB). Screening for mutations in the LAMB3 gene in the patient revealed the previously described hotspot mutation R635X and a novel one basepair deletion in exon 10. The single basepair deletion 1094delA could be detected in the clinically unaffected mother, while the nonsense mutation R635X could not be found in the peripheral blood DNA of either parent. After excluding non-paternity by microsatellite analysis using random markers on chromosomes 3, 8 and 18, we determined that the mutation R635X in the proband was most likely the result of a de novo event or alternatively, germline mosaicism. The parents requested prenatal diagnosis for a second pregnancy, and while the maternal mutation 1094delA could not be detected in DNA from the fetus, unexpectedly, the mutation R635X was present in the chorionic villus DNA. These findings were most consistent with paternal germline mosaicism for the recessive mutation R635X. The results have had a significant impact on the genetic counseling in this family. To our knowledge, this study represents the first documented case of germline mosaicism in junctional epidermolysis bullosa, and serves as a reminder that germline mosaicism should be considered in cases in which a 'new' mutation is found in the offspring of a clinically and/or genetically unaffected parent.

Strategy to assess the efficiency of U1 RNA-hammerhead ribozyme constructs using GFP-tagged targets.

The application of ribozymes for gene therapy of autosomal dominant diseases has become popularized in recent years. Further this technology has widespread utility in the treatment of any disease, acquired or inherited, by inhibition of gene expression. The design of ribozymes is usually accomplished using computer assisted design programs, however they are not very useful in predicting the behavior of the ribozyme in the in vivo setting. To overcome this technical challenge, we developed a simple in vivo strategy to accurately assess the efficiency of ribozyme cleavage that significantly enhances the computer based design programs.