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G Akots

Publications and source records attributed to G Akots.

15 recordsLinked to original sources
PubMed1997

Linkage of genetic markers on human chromosomes 20 and 12 to NIDDM in Caucasian sib pairs with a history of diabetic nephropathy.

The potential contribution of maturity-onset diabetes of the young (MODY) genes to NIDDM susceptibility in African-American and Caucasian NIDDM-affected sibling pairs with a history of adult-onset diabetic nephropathy has been evaluated. Evidence for linkage to NIDDM was found with polymorphic loci that map to the long arms of human chromosomes 20 and 12 in regions containing the MODY1 and MODY3 genes. Nonparametric analysis of chromosome 20 inheritance data collected with the MODY1-linked marker D20S197 provides evidence for linkage to NIDDM with a P value of 0.005 in Caucasian sib pairs using affected sibpair (ASP) analyses. Non-parametric analysis of chromosome 12 inheritance data collected with the MODY3-linked markers D12S349 and D12S86 provides evidence for linkage to NIDDM with P values of 0.04 and 0.006, respectively, in Caucasian sib pairs using similar analyses. No evidence for linkage of MODY1 and MODY3 markers to NIDDM in African-American sib pairs was observed. In addition, no evidence for linkage to MODY2 (glucokinase-associated MODY) was observed with either study population. Results of multipoint maximum logarithm of odds (LOD) score analysis were consistent with the ASP results. A maximum LOD score of 1.48 was calculated for linkage to MODY1-linked loci and 1.45 to MODY3-linked loci in Caucasian sib pairs. Tabulation of allele sharing in affected sib pairs with D20S197 and D12S349 suggests that affected sibling pairs may inherit susceptibility genes simultaneously from chromosome 20 and chromosome 12. The results suggest that genes contributing to NIDDM in the general Caucasian population are located in the regions containing the MODY1 and MODY3 genes.

Adult↗
PubMed1996

Physical and genetic mapping of the muscle phosphofructokinase gene (PFKM): reassignment to human chromosome 12q.

Phosphofructokinase (PFK) is a key rate-limiting enzyme in glycolysis and represents a major control point in the metabolism of glucose. There are at least three known isoforms of PFK in humans, referred to as the muscle, platelet, and liver forms, each of which is differentially expressed in various tissues. The gene for muscle phosphofructokinase, PFKM, is mutated in Tarui disease and conceivably contributes to non-insulin-dependent diabetes mellitus (NIDDM). Based on physical and genetic mapping, we have found that the gene for PFKM does not map to chromosome 1 as previously described, but instead maps to chromosome 12. PCR analysis with a somatic cell hybrid mapping panel using primers derived from intron 6 and exon 18 of the PFKM gene showed consistent amplification of cell lines containing chromosome 12 (concordance, 100%). Fluorescence in situ hybridization analysis with CEPH YAC 762G4, isolated with exon 18 primers, indicated that this clone maps to 12q13, centromeric to the diacylglycerol kinase gene (DAGK) at 12q13. 3. A highly informative genetic marker isolated from YAC 762G4 was used to map PFKM genetically between the CHLC framework markers D12S1090 and D12S390. This placement for 762G4 was significantly proximal to the recently reported locus for a third gene for maturity onset diabetes of the young (MODY). The PFKM-associated microsatellite will be a valuable tool in the evaluation of PFKM in diabetic populations as well as in linkage analysis in families with Tarui disease.

Blotting, Southern↗
PubMed1995

Fructose-1,6-bisphosphatase: genetic and physical mapping to human chromosome 9q22.3 and evaluation in non-insulin-dependent diabetes mellitus.

PCR primers specific to the human liver fructose-1,6-bisphosphatase (FBP) gene were designed and used to isolate a cosmid clone. Physical mapping of the FBP cosmid by FISH, and genetic mapping of an associated GA repeat polymorphism (PIC = 0.35), located the liver FBP gene to chromosome 9q22.3 with no recombination between FBP and the index markers D9S196 (Zmax = 13.2), D9S280 (Zmax = 11.7), D9S287 (Zmax = 15.6), and D9S176 (Zmax = 14.4). Amplification using FBP exon-specific primers with a YAC contig from this region of chromosome 9 further refined the placement of FBP genomic sequences to an approximately 1.7-cM region flanked by D9S280 and D9S287, near the gene for Fanconi anemia group C. Precise localization of the FBP gene enabled evaluation of FBP as a candidate gene for maturity-onset diabetes of the young (MODY) and non-insulin-dependent diabetes (NIDDM) in both Caucasian and African-American families, using the highly informative markers D9S287 and D9S176. Although FBP is a rate-limiting enzyme in gluconeogenesis, using both parametric and nonparametric analysis there was no evidence for linkage of FBP to diabetes in these families.

Animals↗
PubMed1994

Genetic and physical mapping of human recoverin: a gene expressed in retinal photoreceptors.

PURPOSE: Recoverin is a calcium-binding protein that may be involved in phototransduction in mammalian retinal photoreceptors, and is considered to be a candidate gene for retinitis pigmentosa. This study was undertaken to develop the recoverin locus into a polymorphic marker for future linkage studies on retinitis pigmentosa families. METHODS: A human genomic cosmid clone was isolated and used to map the recoverin gene to a human chromosome through hybridization to a panel of somatic hybrid cell line DNAs, and to human metaphase chromosomes by fluorescence in situ hybridization. A dinucleotide repeat polymorphism located within the coding region of the recoverin gene was identified, and used to genetically map the recoverin gene relative to index markers. In addition, three restriction fragment length polymorphisms revealed by the cosmid clone were identified and characterized. RESULTS: Hybridization to the somatic hybrid cell line DNAs localized the recoverin gene to chromosome 17. Recoverin was further localized to 17p12-p13 by fluorescence in situ hybridization. The dinucleotide repeat polymorphism and restriction fragment length polymorphisms at the recoverin locus have a cumulative polymorphic information content = 0.71. CONCLUSIONS: These polymorphic markers and additional closely linked markers will be useful for linkage analysis of families with retinitis pigmentosa.

Base Sequence↗
PubMed1993

A genetic map of chromosome 20q12-q13.1: multiple highly polymorphic microsatellite and RFLP markers linked to the maturity-onset diabetes of the young (MODY) locus.

Multiple highly polymorphic markers have been used to construct a genetic map of the q12-q13.1 region of chromosome 20 and to map the location of the maturity-onset diabetes of the young (MODY) locus. The genetic map encompasses 23 cM and includes 11 loci with PIC values > .50, seven of which have PICs > .70. New dinucleotide repeat polymorphisms associated with the D20S17, PPGB, and ADA loci have been identified and mapped. The dinucleotide repeat polymorphisms have increased the PIC of the ADA locus to .89 and, with an additional RFLP at the D20S17 locus, the PIC of the D20S17 locus to .88. The order of the D20S17 and ADA loci determined genetically (cen-ADA-D20S17-qter) was confirmed by multicolor fluorescence in situ hybridization. The previously unmapped PPGB marker is closely linked to D20S17, with a two-point lod score of 50.53 at theta = .005. These markers and dinucleotide repeat markers associated with the D20S43, D20S46, D20S55, D20S75, and PLC1 loci and RFLPs at the D20S16, D20S17, D20S22, and D20S33 have been used to map the MODY locus on chromosome 20 to a 13-cM (sex averaged) interval encompassing ADA, D20S17, PPGB, D20S16, and D20S75 on the long arm of chromosome 20 and to create a genetic framework for additional genetic and physical mapping studies of the region. With these multiple highly polymorphic loci, any MODY family of appropriate size can be tested for the chromosome 20 linkage.

Base Sequence↗
PubMed1992

A microsatellite polymorphism associated with the PLC1 (phospholipase C) locus: identification, mapping, and linkage to the MODY locus on chromosome 20.

A highly polymorphic (dC-dA)n.(dG-dT)n dinucleotide repeat at the PLC1 locus on human chromosome 20 has been identified. Primers flanking the dinucleotide repeat were used for PCR amplification of the repeat region in 37 informative kindreds from the Centre d'Etude du Polymorphisme Humain. Two-point linkage analysis indicates that PLC1 is closely linked to several chromosome 20 markers, including D20S16 (Zmax = 41.25; theta = 0.07), D20S17 (Zmax = 42.81; theta = 0.09), and ADA (Zmax = 57.24; theta = 0.05). Multipoint linkage analysis places the PLC1 locus between D20S18 and D20S17, 11.2 and 6.6 cM, respectively, from these loci (sex-averaged distances). In addition, the PLC1 gene shows linkage to the maturity-onset diabetes of the young (MODY) locus on chromosome 20 with a lod score of 4.57 at theta = 0.089.

Base Sequence↗
PubMed1992

Physical localization of chromosome 20 markers using somatic cell hybrid cell lines and fluorescence in situ hybridization.

A panel of somatic cell hybrid cell lines containing different parts of human chromosome 20 and fluorescence in situ hybridization have been used to physically localize markers to human chromosome 20. Through these complementary approaches and genetic linkage analysis, D20S16, which is closely linked to the maturity onset diabetes of the young (MODY) locus, was mapped to band 20q12 --> q13.1. The gene for growth hormone-releasing factor (GHRF) was physically mapped and reassigned to 20q11, suggesting that GHRF plays no direct role in MODY. In addition, the genes for the chromosome 20-linked glycogen phosphorylase (GYPB) and the bone morphogenetic protein (BMP2A) have been assigned to chromosome 20p, and the interleukin-6-dependent DNA-binding protein (TCF5) has been assigned to 20q12 --> q13 by hybridization to genomic DNA from the panel of somatic cell hybrid cell lines. These approaches are useful for rapid localization of candidate genes for MODY and other DNA markers mapped to chromosome 20.

Animals↗
PubMed1992

Identification of genetic markers flanking the locus for maturity-onset diabetes of the young on human chromosome 20.

A systematic search for genetic linkage with maturity-onset diabetes of the young (MODY) as expressed in the R.-W. pedigree has been carried out. Evidence for linkage was found with restriction-fragment-length polymorphism loci that map to human chromosome 20. Two-point linkage analysis with CRI-L1214 (D20S16) and MODY gave a log of the odds (lod) score of 4.16 at theta = 0.08. Multipoint linkage analysis with nine restriction-fragment-length polymorphism loci resulted in a lod score of 4.81 with the MODY locus in an approximately 20-cM region bounded by D20S16 and D20S14-D20S18. Examination of the pattern of MODY segregation suggests that additional factors, possibly genetic could be involved in the age of onset of the disease.

Adult↗
PubMed1992

Linkage analysis of maturity-onset diabetes of the young (MODY): genetic heterogeneity and nonpenetrance.

We have analyzed the inheritance of maturity-onset diabetes of the young (MODY) on chromosome 20 in a large multigeneration family, the R.-W. family, and in two other MODY families. Of the four branches of the R.-W. pedigree which have been studied, two have documented early onset of non-insulin-dependent diabetes mellitus (NIDDM), while there is no evidence of early onset in the other two branches. The early-onset branches have apparently inherited the same D20S16 allele from the affected parent, while another D20S16 allele was inherited in the two branches without evidence of early onset. A test for homogeneity, the M-test, using the results of two-point linkage analysis with D20S16 indicates heterogeneity between early- and late-onset branches of the R.-W. family (P less than or equal to .014). In addition, analysis strongly suggests that MODY as expressed in the EDI and WIS families is unlinked to loci on chromosome 20 (P less than or equal to .018-.004). Comparable results are seen when the data are analyzed by the HOMOG program. Three polymorphic loci-D20S16, D20S17, and ADA--show no recombination with the MODY locus when two-point linkage analysis is used in the early-onset branches of the family. The multipoint lod score in the early-onset branches of the R.-W. family is 10.16, with the most likely location being between D20S4 and D20S17. Multipoint linkage analysis using the CHROMPICS option of the program CRI-MAP has been used to follow inheritance of the MODY disease locus. This analysis has identified two cases of possible nonpenetrance in the early-onset branches of the family (odds of at least 156:1), as determined by the appearance of apparent isolated double crossovers at the MODY locus in these unaffected individuals.

Adolescent↗
PubMed1990

Chromosomal localization of ZFX--a human gene that escapes X inactivation--and its murine homologs.

The ZFY gene, found in the sex-determining region of the human Y chromosome, encodes a zinc-finger protein that may be the pivotal sex-determining signal. A closely related gene, ZFX, is found on the human X chromosome, and it may also function in sex determination. ZFX is one of a few genes on the human X chromosome that are known to escape X inactivation. We report the localization of ZFX, by meiotic linkage analysis and physical mapping, distal to POLA but proximal to DXS41 (p99-6), near the boundary of bands Xp21.3 and Xp22.1. (Our results suggest the following order of loci in Xp21-p22: cen-DMD-[GK,AHC]-DXS67 (pB24)-POLA-ZFX-[DXS41 (p99-6), DXS274 (CRI-L1391)]-DXS43 (pD2)-pter.) These findings contradict the model that escape from X inactivation is limited to genes near the short-arm telomere (i.e., in Xp22.3). Instead, escape from X inactivation is likely a property of several noncontiguous segments of the X chromosome. Curiously, in mouse, the homologous Zfx gene maps to X chromosome band D, near the center from which an X-inactivating signal is thought to spread. As judged by comparative mapping, it appears that an X-chromosomal segment that spans the ZFX and DMD genes has remained grossly intact during the divergence of mouse and human from a common ancestor. Conservation of this chromosomal segment may extent to marsupials, where homologs of the ZFX and DMD genes have been observed in proximity, but on an autosome. While autosomal homologs of ZFX have not been observed in other placental mammals, a locus derived from a processed Zfx transcript is found on mouse chromosome 10 band B3 or B4.

Animals↗
PubMed1988

Identification of more than 500 RFLPs by screening random genomic clones.

As part of our genome-mapping effort, we undertook a large-scale screening study to identify RFLPs useful as genetic markers. Some 1,664 single-copy or repeat-containing phage clones from a Charon 4A genomic library were tested for polymorphism against a panel of DNAs, from five unrelated individuals, digested with eight restriction enzymes. Approximately 30% (515) of the clones revealed polymorphism by Southern hybridization; 67 loci detected had PIC values greater than .5. Restriction enzymes MspI, TaqI, and RsaI were most efficient in detecting polymorphism within the 1-20-kb-fragment size range resolved. With only one exception each of the clones detected polymorphism originating from a single locus.

Cloning, Molecular↗
PubMed1987

Genetic linkage map of human chromosome 7 with 63 DNA markers.

High-density genetic maps of individual human chromosomes will permit accurate localization of disease-associated genes and provide signposts that will be useful in the construction of physical maps. We have constructed a genetic map of chromosome 7 with 63 polymorphic DNA markers by using segregation data from 23 three-generation families and recently developed multilocus linkage-analysis techniques. The map spans 250 centimorgans in females and 170 centimorgans in males, with much of the difference being concentrated in a few intervals. The density and informativeness of the markers are such that there is a high probability of detecting linkage to any disease gene on this chromosome for which 20 phase-known meioses are available.

Chromosome Mapping↗
PubMed1986

Homogeneous, liposome-based assay for total complement activity in serum.

This is a rapid, homogeneous, liposome-based assay for total complement activity in human serum. Liposome-encapsulated enzyme is unmasked by the action of complement on liposomes carrying surface-bound immune complexes. The amount of unmasked enzyme, proportional to the concentration of added complement, is quantified by measuring the absorbance of enzymically produced product at 410 nm. Complement activity in serum samples is extrapolated from a standard curve generated from dilutions of a guinea pig serum containing a known activity of complement. Interassay CVs were less than 7.0% and intra-assay CVs less than 2.8% for serum pools with complement activities spanning the normal range. Test results correlate as well with those of the hemolytic complement test (r = 0.80) as the latter correlates with itself (r = 0.82), and also correlate reasonably with measurements of complement components C3 (r = 0.62) and C4 (r = 0.74). Values for a normal population are reported. Advantages of this test include stability of reagents, speed, accuracy, simplicity, and avoidance of radioisotopes.

Alkaline Phosphatase↗
PubMed1984

Rapid, homogeneous phase, liposome-based assays for total complement activity.

A simple, rapid assay for determining total complement activity has been developed. Complement activity is quantitated spectrophotometrically by measuring the amount of liposome-encapsulated enzyme unmasked by the action of anti-Dnp antibody and complement on Dnp-tagged liposomes. The assay is homogeneous in nature and is nonisotopic. The activity of complement in guinea pig serum has been measured and shown to be proportional to complement concentration. The assay was modified to measure the complement-fixing titer of anti-Dnp antibody preparations. We have compared two monoclonal anti-Dnp antibodies (IgG1 and IgM) for their ability to fix complement. The IgM antibody preparation was 450-fold more effective than the IgG1 preparation in mediating complement-dependent damage to Dnp liposomes. In addition, the test was modified to measure complement fixation by soluble antigen-antibody complexes. This complement fixation format is capable of detecting 2 pmol Dnp antigen.

2,4-Dinitrophenol↗