June A. White

Bio: June A. White is an academic researcher from University of Minnesota. The author has contributed to research in topics: Gene mapping & Genetic linkage. The author has an hindex of 13, co-authored 16 publications receiving 2075 citations.

Genetic linkage evidence for a familial Alzheimer's disease locus on chromosome 14.

Abstract: Linkage analysis was used to search the genome for chromosomal regions harboring familial Alzheimer's disease genes. Markers on chromosome 14 gave highly significant positive lod scores in early-onset non-Volga German kindreds; a Zmax of 9.15 (theta = 0.01) was obtained with the marker D14S43 at 14q24.3. One early-onset family yielded a lod score of 4.89 (theta = 0.0). When no assumptions were made about age-dependent penetrance, significant results were still obtained (Zmax = 5.94, theta = 0.0), despite the loss of power to detect linkage under these conditions. Results for the Volga German families were either negative or nonsignificant for markers in this region. Thus, evidence indicates a familial Alzheimer's disease locus on chromosome 14.

Dementia of the Alzheimer Type: Clinical Genetics, Natural History, and Associated Conditions

Abstract: • Relatives of 125 probands, who had dementia of the Alzheimer type as proved by autopsy, were subjects of a genetic investigation. The relatives exhibited an excess of dementing illness consistent with genetic transmission. Risk to relatives decreased sharply as severity of the proband's illness decreased. Also, when compared with a control group and the general population, the relatives had excesses of Down's syndrome, lymphoma, and immune diatheses. These associated conditions also were more likely to be present when the proband had severe illness. Mortality at all ages was increased among the relatives.

Linkage and mutational analysis of familial Alzheimer disease kindreds for the APP gene region

Abstract: A large number of familial Alzheimer disease (FAD) kindreds were examined to determine whether mutations in the amyloid precursor protein (APP) gene could be responsible for the disease. Previous studies have identified three mutations at APP codon 717 which are pathogenic for Alzheimer disease (AD). Samples from affected subjects were examined for mutations in exons 16 and 17 of the APP gene. A combination of direct sequencing and single-strand conformational polymorphism analysis was used. Sporadic AD and normal controls were also examined by the same methods. Five sequence variants were identified. One variant at APP codon 693 resulted in a Glu-->Gly change. This is the same codon as the hereditary cerebral hemorrhage with amyloidosis-Dutch type Glu-->Gln mutation. Another single-base change at APP codon 708 did not alter the amino acid encoded at this site. Two point mutations and a 6-bp deletion were identified in the intronic sequences surrounding exon 17. None of the variants could be unambiguously determined to be responsible for FAD. The larger families were also analyzed by testing for linkage of FAD to a highly polymorphic short tandem repeat marker (D21S210) that is tightly linked to APP. Highly negative LOD scores were obtained for the family groups tested, and linkage was formally excluded beyond theta = .10 for the Volga German kindreds, theta = .20 for early-onset non-Volga Germans, and theta = .10 for late-onset families. LOD scores for linkage of FAD to markers centromeric to APP (D21S1/S11, D21S13, and D21S215) were also negative in the three family groups. These studies show that APP mutations account for AD in only a small fraction of FAD kindreds.

The apolipoprotein E/CI/CII gene cluster and late-onset Alzheimer disease

Abstract: The chromosome 19 apolipoprotein E/CI/CII gene cluster was examined for evidence of linkage to a familial Alzheimer disease (FAD) locus. The family groups studied were Volga German (VG), early-onset non-VG (ENVG; mean age at onset <60 years), and late-onset families. A genetic association was observed between apolipoprotein E (ApoE) allele e4 and FAD in late-onset families; the e4 allele frequency was .51 in affected subjects, .37 in at-risk subjects, .11 in spouses, and .19 in unrelated controls. The differences between the e4 frequencies in affected subjects versus controls and in at-risk subjects versus controls were highly significant (standard normal deviate [ZSND]) = 7.37, P < 10−9; and ZSND = 4.07, P < .00005, respectively). No association between the e4 allele and FAD was observed in the ENVG or VG groups. A statistically significant allelic association between e4 and AD was also observed in a group of unrelated subjects; the e4 frequency was .26 in affected subjects, versus .19 in controls (ZSND = 2.20, P < .03). Evidence of linkage of ApoE and ApoCII to FAD was examined by maximum-likelihood methods, using three models and assuming autosomal dominant inheritance: (1) age-dependent penetrance, (2) extremely low (1%) penetrance, and (3) age-dependent penetrance corrected for sporadic Alzheimer disease (AD). For ApoCII in late-onset families, results for close linkage were negative, and only small positive lod-score-statistic (Z) values were obtained (model 1, maximum Z [Zmax] = 0.61, recombination fraction [θ] = .30; model 2, Zmax = 0.47, θ = .20). For ApoE in late-onset kindreds, positive Z values were obtained when either allele frequencies from controls (model 1, Zmax = 2.02, θ = .15; model 2, Zmax = 3.42, θ = .05) or allele frequencies from the families (model 1, Zmax = 1.43, θ = .15; model 2, Zmax = 1.70, θ = .05) were used. When linkage disequilibrium was incorporated into the analysis, the Z values increased (model 1, Zmax = 3.17, θ = .23; model 3, Zmax = 1.85, θ = .20). For the ENVG group, results for ApoE and ApoCII were uniformly negative. Affected-pedigree-member analysis gave significant results for the late-onset kindreds, for ApoE (ZSND = 3.003, P = .003) and ApoCII (ZSND = 2.319, P = .016), when control allele frequencies were used but not when allele frequencies were derived from the families.

Brain metabolism as measured with positron emission tomography: serial assessment in a patient with familial Alzheimer's disease.

Abstract: This paper presents, for the first time, repeated assessments of cerebral metabolism and neuropsychological competence in early Alzheimer9s disease. Regional cerebral metabolic rates for glucose were measured with positron emission tomography and 18 F-fluoro-2-deoxy-D-glucose on three occasions at 8-month intervals, in a 57-year-old man with Alzheimer9s disease of 2 1 / 2 years9 duration and with a family history of neuropathologically confirmed Alzheimer9s disease. Data were compared with mean cerebral metabolic rates from 12 healthy men. No differences in regional cerebral metabolic rates for glucose were found on the initial patient scan, whereas metabolism on the second and third scans was reduced significantly in the parietal lobes and bilaterally in some parietal lobe regions. Memory loss was demonstrable at the first scan, but then and at later scans, other aspects of cognitive performance remained within normal limits (Wechsler Adult Intelligence Scale, Boston Naming Test, Two-dimensional Block Construction). The results show that memory loss can precede a measurable reduction of cerebral metabolism in early Alzheimer9s disease, but that later reductions in parietal lobe metabolism may not be accompanied by additional measurable neuropsychological deficits.

Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families

Abstract: The apolipoprotein E type 4 allele (APOE-epsilon 4) is genetically associated with the common late onset familial and sporadic forms of Alzheimer9s disease (AD). Risk for AD increased from 20% to 90% and mean age at onset decreased from 84 to 68 years with increasing number of APOE-epsilon 4 alleles in 42 families with late onset AD. Thus APOE-epsilon 4 gene dose is a major risk factor for late onset AD and, in these families, homozygosity for APOE-epsilon 4 was virtually sufficient to cause AD by age 80.

Alzheimer's Disease: Genes, Proteins, and Therapy

Abstract: Rapid progress in deciphering the biological mechanism of Alzheimer's disease (AD) has arisen from the application of molecular and cell biology to this complex disorder of the limbic and association cortices. In turn, new insights into fundamental aspects of protein biology have resulted from research on the disease. This beneficial interplay between basic and applied cell biology is well illustrated by advances in understanding the genotype-to-phenotype relationships of familial Alzheimer's disease. All four genes definitively linked to inherited forms of the disease to date have been shown to increase the production and/or deposition of amyloid β-protein in the brain. In particular, evidence that the presenilin proteins, mutations in which cause the most aggressive form of inherited AD, lead to altered intramembranous cleavage of the β-amyloid precursor protein by the protease called γ-secretase has spurred progress toward novel therapeutics. The finding that presenilin itself may be the long-sought γ-...

Cloning of a gene bearing missense mutations in early-onset familial Alzheimer's disease

Abstract: Some cases of Alzheimer's disease are inherited as an autosomal dominant trait. Genetic linkage studies have mapped a locus (AD3) associated with susceptibility to a very aggressive form of Alzheimer's disease to chromosome 14q24.3. We have defined a minimal cosegregating region containing the AD3 gene, and isolated at least 19 different transcripts encoded within this region. One of these transcripts (S182) corresponds to a novel gene whose product is predicted to contain multiple transmembrane domains and resembles an integral membrane protein. Five different missense mutations have been found that cosegregate with early-onset familial Alzheimer's disease. Because these changes occurred in conserved domains of this gene, and are not present in normal controls, they are likely to be causative of AD3.

Association of apolipoprotein E allele epsilon 4 with late-onset familial and sporadic Alzheimer's disease.

Abstract: Apolipoprotein E, type epsilon 4 allele (APOE epsilon 4), is associated with late-onset familial Alzheimer's disease (AD). There is high avidity and specific binding of amyloid beta-peptide with the protein ApoE. To test the hypothesis that late-onset familial AD may represent the clustering of sporadic AD in families large enough to be studied, we extended the analyses of APOE alleles to several series of sporadic AD patients. APOE epsilon 4 is significantly associated with a series of probable sporadic AD patients (0.36 +/- 0.042, AD, versus 0.16 +/- 0.027, controls [allele frequency estimate +/- standard error], p = 0.00031). Spouse controls did not differ from CEPH grandparent controls from the Centre d'Etude du Polymorphisme Humain (CEPH) or from literature controls. A large combined series of autopsy-documented sporadic AD patients also demonstrated highly significant association with the APOE epsilon 4 allele (0.40 +/- 0.026, p < or = 0.00001). These data support the involvement of ApoE epsilon 4 in the pathogenesis of late-onset familial and sporadic AD. ApoE isoforms may play an important role in the metabolism of beta-peptide, and APOE epsilon 4 may operate as a susceptibility gene (risk factor) for the clinical expression of AD.