Genomic organization of the human cholesterol-responsive ABC transporter ABCA7: Tandem linkage with the minor histocompatibility antigen HA-1 gene
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Authors: Kaminski, WE; Piehler, A; Schmitz, G
Abstract
We have recently cloned a novel cholesterol-responsive ABC transporter, designated ABCA7, which is predominantly expressed in human leukocytes. Here we report the structure of the human ABCA7 gene. The ABCA7 gene spans a region of similar to 32 kb and comprises 46 exons. Its putative promoter sequence contains potential binding sites for transcription factors with roles in hematopoiesis and cholesterol metabolism. Surprisingly, sequence analysis of the ABCA7 3' gene flanking region revealed that the terminal exon of ABCA7 borders immediately on the 5' end of the coding region of the recently identified human minor histocompatibility antigen HA-1. We demonstrate that the coding regions of ABCA7 and HA-1 are physically separated by a 1.7-kb intergene region. Subsequent genomic structure analysis showed that the HA-1 gene consists of 23 exons which extend across a 16-kb genomic region. Our results provide evidence that the genes for the human minor histocompatibility antigen HA-1 and the ABC transporter ABCA7 are arranged in a head-to-tail array and that both genes localize to a common locus of similar to 48 kb size on chromosome 19p13.3. (C) 2000 Academic Press.
Association among ABCA7 Gene Polymorphism, rs3764650 and Alzheimer's Disease in the Turkish Population
CLINICAL AND INVESTIGATIVE MEDICINE
Authors: Oznur, Murat; Hatipoglu, Omer F.; Ayturk, Zubeyde; Dede, Serap; Akbas, Kubra; Aydin, Duygu; Urhan, Ayse; Artut, Elif; Karaaslan, Afranur
Abstract
Purpose: Alzheimer's disease (AD), the most common form of dementia, is an irreversible and progressive neurodegenerative disease that is characterized by the progressive loss of cognitive functions, behavioral and psychological disorders and a decrease in daily routine activities. Among people aged 65 years and over, AD is steadily increasing. Genome-wide association studies have shown that various gene polymorphisms are highly associated with the pathogenesis of AD. Among them, ABCA7 gene polymorphism has been identified as one of the genetic risks. The purpose of this study was to investigate the relationship among ABCA7 gene polymorphism, rs3764650 and AD, and to determine if it could be use as a biomarker for AD susceptibility in the Turkish population. Methods: Peripheral blood samples of 54 Alzheimer's patients and 57 control subjects were collected. Genomic DNA was isolated by SDS/proteinase K treatment followed by phenolchloroform extraction and ethanol precipitation. The presence of the ABCA7 gene rs3764650 polymorphism was investigated by PCR-RFLP and selected samples were confirmed by DNA sequencing. Results: In the Turkish population, the ABCA7 gene rs3764650 polymorphism did not show a significant association with AD when compared with the control group (p>0.05). APOE-epsilon 3 allele frequencies were higher in both AD patients and control subjects (76.85% and 84.21%, respectively). Conclusion: Both previously published studies and our current study did not cover the complete genetic variation in the gene. To detect variants that are disease-related, studies with larger sample sizes are needed.