Abdirashid M Shire | PubMed Health

PubMed2006

SINE elements of Entamoeba dispar.

Entamoeba histolytica and E. dispar are closely related protozoan parasites; the former causes clinical amoebiasis in humans while the latter appears to be non-pathogenic. The molecular biology of E. histolytica shows a number of unusual features, one of which is the abundance of polyadenylated but apparently untranslatable mRNAs produced; many of these are the product of at least three families of SINEs (EhSINE1-3). Here we show that the genome of E. dispar contains numerous copies of a SINE element (EdSINE1) whose 5'- and 3'-ends are very similar to those of EhSINE1 but with a much less similar middle portion. Twelve out of 18 copies examined had target site duplications. In none out of six cases examined was there a SINE element in the homologous region of the E. histolytica genome but a single copy of EdSINE1 is present in E. histolytica where it is identified as EhSINE3.

Amino Acid Sequence↗

PubMed2006

Ethnic variation in AMD-associated complement factor H polymorphism p.Tyr402His.

Age-related macular degeneration (AMD) is the most common cause of irreversible visual loss in the developed world. Previous studies have demonstrated that the c.1204T>C, p.Tyr402His allelic variant in the complement factor H (CFH) gene is associated with an approximately three-fold increased risk for AMD in Caucasians of predominantly European descent. Both the prevalence as well as the phenotypic spectrum of AMD varies widely among persons of different ethnicities. We hypothesized that populations with a lower prevalence of AMD might also have a lower prevalence of the CFH risk allele. In this study we sought to determine the frequency of this sequence variant in control populations of Caucasians, African Americans, Hispanics, Somalis, and Japanese. Normal control populations were assembled for each ethnic group: Caucasian (n=148), Somali (n=128), African American (n=75), Hispanic (n=81), and Japanese (n=82). Individuals were genotyped using a restriction digest assay and the frequency of the C allele at nucleotide position 1204 of the CFH gene was determined. A bioinformatic approach was used to identify SNPs in linkage disequilibrium with rs1061170 (c.1204T>C, p.Tyr402His) from the human haplotype map project database (HapMap) in order to validate the findings. We found widely discordant frequencies of the risk allele between some of the different ethnic groups: Japanese 0.07+/-0.02, Hispanics 0.17+/-0.03, African-Americans 0.35+/-0.04, Caucasians 0.34+/-0.03, and Somalis 0.34+/-0.03. Allele frequencies generated by analysis of the HapMap database were consistent with these findings. This study suggests that there are other yet unidentified genetic factors important in the pathogenesis of AMD that may mitigate the effects of c.1204T>C, p.Tyr402His variant.

Aged↗