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Age of onset and genetic predisposition in familial Alzheimer's disease
S128
FOURTH INTERNATIONAL CONFERENCE ON ALZHEIMER’S DISEASE
Alzheimer disease. To clarify the role of iron in brain, we have begun a systematic study of the brain ferritins. Ferritins are comprised of 24 heavy (H) and 24 light (L) subunits. There are at least 15 different human ferridn H chain sequences on 12 different chromosomes. Sequences homologous to the L subunit have bean found on 3 different chromosomes. The signiticance of these H and L Chain families is not clear. So far, only one functional ferritin H chain gene and one functional ferritin L chain gene have been isolated and characterized. These reside on chromosomes 11 and 19, respectively. We have isolated two types of ferritin heavy (H) chain cDNA clones from cDNA libraries of human fetal and adult brain; one corresponds to the wellcharacterized functional liver fe.nitin H chain mRNA. The other contajm an additional 279 bp sequence in the 3’-untranslatedregion. To map the 279 bp sequence, PCR amplification was carried out using DNA from rodent x human hybrid cell lines containingsingle humanchromosomes as templateand oligomeric primers homologous to the 3’end of the 279 bp sequence and to a coding sequence 5’ to a 158 bp untranslatedferritin H chain region conserved in liver and brain. PCR product was generated only from hybrid cell DNA containing chromosome 11. Southern analysis of this DNA indicated that sequences homologous to the PCR product were present in one Eco Rl band (17.5 kb), two Hind JIIbands (7.4 and 2.3 kb), and Bgl II bands (23 and 4 kb). These data agree with a previous report that restriction fragments of these sizes are derived from two sepamte ferridn H chain genes on chromosome I1 - the well-characterizedfunctionalLiver ferritin H chain gene, and a putative pseudogene. Interestingly, the oligome-r homologous to the 3’end of the 279 bp sequence hybridized only to the Eco JU 17.5 kb, the Hind Ill 7.4 kb and the Bgl JJ 23 kb bands - fragments reported to contain the timctional liver fenitin H chain gene. Differential processing of a primary RNA transcriptfrom the functionalferriiin H chain gene on chromosome 11 might account for the two types of fenitin H chain mRNAs in brain.
smoking and Alzheimer’s disease (AD). Two studies noted this association only among AD cases with a family history of AD, suggesting genes may be responsible. We examined this association in elderly twin pairs. Smoking history was obtained from structured questionnaires administered to the subject or to a collateral respondent. In an unmatched case control comparison, AD cases and controls differed on history of smoking (20+ pack-year history, odds ratio (ox.) = 0.43; 95% confidence interval (c.i.) 0.20 - 0.93; p < 0.05), suggesting a reduced risk of AD in smokers. However, matched co-twin control analyses with 20 monozygotic (MZ) and 21 dizygotic (DZ) twin pairs discordant for AD showed a reduced association between smoking and AD (ox = 0.67, 95% c.i. 0.21 - 2.0). To investigate confounding with genes, we compared the odds ratios in MZ and DZ pairs and found a significant difference (dependent logistic model, x2 = 2.72, p = 0.049, one-sided test), with inverse association between AD and smoking apparent only in the DZ pairs. In this sample, smoking was inversely related to the dose of allele ~4 for Apolipoprotein E (ApoE), while AD was directly related to &4dose. Pairs who were matched on ApoE genotype (20 MZ and 13 DZ pairs) showed an odds ratio of 1.0 for smoking and AD, but the odds ratio in ApoE-unmatched DZ pairs was 0.25. These data suggest that genetic confounding may explain the association between AD and smoking. The polymorphic alleles of ApoE may account at least in part for this effect.
528 AGE OF ONSETANDGENETICPREDISPOSITIONIN FAMILIAL ALZEEIMER’SDISEASE
526 MOLECULARGENETICSOF HEREDITARYDYSPHASICDEMENTIA C.Ll.endon, S. Shears, F.Busfield, C.J. Talbot. J. Renner, J.C.Morris*, A.M. Goate Department of Psychiatry; Department of Neurology*, Washington University Medical School, St Louis, MO 63 110 Hereditary Dysphasic Dementia (HDD) is a rare cerebral cortical degenerative disorder with an apparent autosomal dominant pattern of inheritance. A total of 26 affected individuals have been identified from two large unrelated kindred’s. In both kindred’s the average age of onset of the disease is in the early sixties and has an average duration of about 8 years. The clinical and pathological presentation of HDD reveals similarities with Pick’s disease, Priori dementias and Alzheimer’s disease (AD). Here we report an investigation of whether HDD represents a phenotypic variant of AD or Prion dementia, or has a distinct etiology. We have isolated DNA from the leukocytes of both affected and unaffected family members and applied the following linkage and sequencing strategies. In the larger of the two kindred’s, genetic linkage analysis was performed using highly polymorphic markers which do not show recombination with the gene or loci of interest. Linkage to two loci associated with AD was investigated; the amyloid precursor protein gene (APP), within which 5 mutations associated with AD have been reported, and an AD locus associated with the majority of early onset AD cases located to 14q24.3. Similarly, linkage to the Huntingdon’s disease locus on and the Prion protein (PrP) gene was analysed. In view of the recent evidence of an association between sporadic and familial late onset AD and the E4 allele of the ApoE gene, ApoE phenotypes have been established in the larger HDD kindred. None of the known mutations in the PrP gene have been detected as shown by direct sequencing from polymerase chain reaction products. None of the known mutations in exons 16 and 17 of the APP gene have been found using this method, nor any other deviations from the normal sequence in these exons. These studies show that HDD does not appear to be a phenotypic variant of the known prion dementias or AD. We have recently started a genome search to identify the disease locus in these families.
527 CONFOUNDING WITH GENES MAY EXPLAIN TJ-JEINVERSE ASSOCIATION OF SMOKING AND ALZHEIMER’S DISEASE. B.L. Plassman, J.C.S. Breimer, K.A. Welsh, M.J. Helms. Dept. Psychiatry, Bryan Alzheimer’s Disease Research Center, Duke University Medical Center, Durham, NC 27710 USA. Several studies have reported an inverse association between history of
F Crawford, C Bennett,A Osborne,P Diaz,M Mullan. Molecular Genetics Laboratory, Depariment of Psychiatry,Universily of South Florida, 3515 E Fletcher Av., Tampa,Florida,33613.
Weand others have previously shown thrillAlzheimer’s Disease (AD) is aeliologically heterogeneous. The most us&l clinical features which can be related lo a&logy are familial@ and age of onset. Early onset familial AD IS transmitted as an autosomal dominant. Initial linkageanalysisto markers on chromosome 2 1 in a set of British pedigrees was confounded by genetic heterogeneity, allowing the detection of a gene but mislocalising it. Subsequentanalysis in single pedigrees led lo the debxtion of linkage and the identification of mutations at the C-terminal’, 2 and lhe N-~enninal 3 of the D-amyloidsequence in the a-APPgeneon thatchromosome.The mutations co-segregate completely with age dependent occurrenceof the disease in our data set. A second locus showing linkage of early onset AD to chrC~~uu~0,rh~ I4 llaa IccwUy LnxrrLupulor h& ilrld wndirnied lhru: oIllet d&i sets including our own. Progress in isolating the causative gene will be reported. Although several clinical features occur more frequently in early Onsetfamilial disease, no particular feature demarcates either the chromosome 2 I orchromosome 14 linked forms of the disorder. However, the mean age of familial Onsetseems b be a robust feature reflecting etiology; the chromosome 14 linked families having an earlier onset age than the D-APPmutatedfamilie&. By ccwdmstto these autcsomal dominant loci, the AFQE lccus has recently been associated with late onSetfamilial and non-familial disease’l. We will discuss an analysis of variance of survival time in late onset families in relation to APOE genotype. 1. Goate et al. (1991) Notwe 349,704-706. 2. Cbanier H&in et al. (1991) Nafure353. X44-846 3. Mullan et al. 1992. Nafure Gener.1. 345-347. 4. Schellenberg et al, 1992, Science i58,668671.5. MullA et al, 1992, Nalure Gener 2, 340-342. 6. Mullan et al. Neuropsychialric Genetics, 48:129-130. 7. Corderet al. (1993) Science 261,921.
529 CLINICAL AND GENEALOGJC STUDY OF A NEW FAMILIAL ALZHEJMER’S DISEASE (FAD). G. Capocchil, A. Picchiarellil, A.C. Bruni* and G. Macchi3. ‘Institute of Neurology, University of Perugia, Italy, 2S.M.I.D. Center, General Hospital, Lamezia Terme, Italy, 3Jnstitute of Neurology, Catholic University, Rome, Italy. The clinical and genealogical aspects of a family of Calabria origin, at present living in Umbria, affected by late onset have been studied. The family is composed by 151 subjects across 6 generations. 8 subjects have been identified as AD affected, 2 by direct clinical assessment, 2 by analysis of the medical records and 4 by analysis of the medical history. In one case the diagnosis has been confirmed histologically by cortical biopsy. In all affected
FOURTH INTERNATIONAL CONFERENCE ON ALZHEIMER’S DISEASE
Alzheimer disease. To clarify the role of iron in brain, we have begun a systematic study of the brain ferritins. Ferritins are comprised of 24 heavy (H) and 24 light (L) subunits. There are at least 15 different human ferridn H chain sequences on 12 different chromosomes. Sequences homologous to the L subunit have bean found on 3 different chromosomes. The signiticance of these H and L Chain families is not clear. So far, only one functional ferritin H chain gene and one functional ferritin L chain gene have been isolated and characterized. These reside on chromosomes 11 and 19, respectively. We have isolated two types of ferritin heavy (H) chain cDNA clones from cDNA libraries of human fetal and adult brain; one corresponds to the wellcharacterized functional liver fe.nitin H chain mRNA. The other contajm an additional 279 bp sequence in the 3’-untranslatedregion. To map the 279 bp sequence, PCR amplification was carried out using DNA from rodent x human hybrid cell lines containingsingle humanchromosomes as templateand oligomeric primers homologous to the 3’end of the 279 bp sequence and to a coding sequence 5’ to a 158 bp untranslatedferritin H chain region conserved in liver and brain. PCR product was generated only from hybrid cell DNA containing chromosome 11. Southern analysis of this DNA indicated that sequences homologous to the PCR product were present in one Eco Rl band (17.5 kb), two Hind JIIbands (7.4 and 2.3 kb), and Bgl II bands (23 and 4 kb). These data agree with a previous report that restriction fragments of these sizes are derived from two sepamte ferridn H chain genes on chromosome I1 - the well-characterizedfunctionalLiver ferritin H chain gene, and a putative pseudogene. Interestingly, the oligome-r homologous to the 3’end of the 279 bp sequence hybridized only to the Eco JU 17.5 kb, the Hind Ill 7.4 kb and the Bgl JJ 23 kb bands - fragments reported to contain the timctional liver fenitin H chain gene. Differential processing of a primary RNA transcriptfrom the functionalferriiin H chain gene on chromosome 11 might account for the two types of fenitin H chain mRNAs in brain.
smoking and Alzheimer’s disease (AD). Two studies noted this association only among AD cases with a family history of AD, suggesting genes may be responsible. We examined this association in elderly twin pairs. Smoking history was obtained from structured questionnaires administered to the subject or to a collateral respondent. In an unmatched case control comparison, AD cases and controls differed on history of smoking (20+ pack-year history, odds ratio (ox.) = 0.43; 95% confidence interval (c.i.) 0.20 - 0.93; p < 0.05), suggesting a reduced risk of AD in smokers. However, matched co-twin control analyses with 20 monozygotic (MZ) and 21 dizygotic (DZ) twin pairs discordant for AD showed a reduced association between smoking and AD (ox = 0.67, 95% c.i. 0.21 - 2.0). To investigate confounding with genes, we compared the odds ratios in MZ and DZ pairs and found a significant difference (dependent logistic model, x2 = 2.72, p = 0.049, one-sided test), with inverse association between AD and smoking apparent only in the DZ pairs. In this sample, smoking was inversely related to the dose of allele ~4 for Apolipoprotein E (ApoE), while AD was directly related to &4dose. Pairs who were matched on ApoE genotype (20 MZ and 13 DZ pairs) showed an odds ratio of 1.0 for smoking and AD, but the odds ratio in ApoE-unmatched DZ pairs was 0.25. These data suggest that genetic confounding may explain the association between AD and smoking. The polymorphic alleles of ApoE may account at least in part for this effect.
528 AGE OF ONSETANDGENETICPREDISPOSITIONIN FAMILIAL ALZEEIMER’SDISEASE
526 MOLECULARGENETICSOF HEREDITARYDYSPHASICDEMENTIA C.Ll.endon, S. Shears, F.Busfield, C.J. Talbot. J. Renner, J.C.Morris*, A.M. Goate Department of Psychiatry; Department of Neurology*, Washington University Medical School, St Louis, MO 63 110 Hereditary Dysphasic Dementia (HDD) is a rare cerebral cortical degenerative disorder with an apparent autosomal dominant pattern of inheritance. A total of 26 affected individuals have been identified from two large unrelated kindred’s. In both kindred’s the average age of onset of the disease is in the early sixties and has an average duration of about 8 years. The clinical and pathological presentation of HDD reveals similarities with Pick’s disease, Priori dementias and Alzheimer’s disease (AD). Here we report an investigation of whether HDD represents a phenotypic variant of AD or Prion dementia, or has a distinct etiology. We have isolated DNA from the leukocytes of both affected and unaffected family members and applied the following linkage and sequencing strategies. In the larger of the two kindred’s, genetic linkage analysis was performed using highly polymorphic markers which do not show recombination with the gene or loci of interest. Linkage to two loci associated with AD was investigated; the amyloid precursor protein gene (APP), within which 5 mutations associated with AD have been reported, and an AD locus associated with the majority of early onset AD cases located to 14q24.3. Similarly, linkage to the Huntingdon’s disease locus on and the Prion protein (PrP) gene was analysed. In view of the recent evidence of an association between sporadic and familial late onset AD and the E4 allele of the ApoE gene, ApoE phenotypes have been established in the larger HDD kindred. None of the known mutations in the PrP gene have been detected as shown by direct sequencing from polymerase chain reaction products. None of the known mutations in exons 16 and 17 of the APP gene have been found using this method, nor any other deviations from the normal sequence in these exons. These studies show that HDD does not appear to be a phenotypic variant of the known prion dementias or AD. We have recently started a genome search to identify the disease locus in these families.
527 CONFOUNDING WITH GENES MAY EXPLAIN TJ-JEINVERSE ASSOCIATION OF SMOKING AND ALZHEIMER’S DISEASE. B.L. Plassman, J.C.S. Breimer, K.A. Welsh, M.J. Helms. Dept. Psychiatry, Bryan Alzheimer’s Disease Research Center, Duke University Medical Center, Durham, NC 27710 USA. Several studies have reported an inverse association between history of
F Crawford, C Bennett,A Osborne,P Diaz,M Mullan. Molecular Genetics Laboratory, Depariment of Psychiatry,Universily of South Florida, 3515 E Fletcher Av., Tampa,Florida,33613.
Weand others have previously shown thrillAlzheimer’s Disease (AD) is aeliologically heterogeneous. The most us&l clinical features which can be related lo a&logy are familial@ and age of onset. Early onset familial AD IS transmitted as an autosomal dominant. Initial linkageanalysisto markers on chromosome 2 1 in a set of British pedigrees was confounded by genetic heterogeneity, allowing the detection of a gene but mislocalising it. Subsequentanalysis in single pedigrees led lo the debxtion of linkage and the identification of mutations at the C-terminal’, 2 and lhe N-~enninal 3 of the D-amyloidsequence in the a-APPgeneon thatchromosome.The mutations co-segregate completely with age dependent occurrenceof the disease in our data set. A second locus showing linkage of early onset AD to chrC~~uu~0,rh~ I4 llaa IccwUy LnxrrLupulor h& ilrld wndirnied lhru: oIllet d&i sets including our own. Progress in isolating the causative gene will be reported. Although several clinical features occur more frequently in early Onsetfamilial disease, no particular feature demarcates either the chromosome 2 I orchromosome 14 linked forms of the disorder. However, the mean age of familial Onsetseems b be a robust feature reflecting etiology; the chromosome 14 linked families having an earlier onset age than the D-APPmutatedfamilie&. By ccwdmstto these autcsomal dominant loci, the AFQE lccus has recently been associated with late onSetfamilial and non-familial disease’l. We will discuss an analysis of variance of survival time in late onset families in relation to APOE genotype. 1. Goate et al. (1991) Notwe 349,704-706. 2. Cbanier H&in et al. (1991) Nafure353. X44-846 3. Mullan et al. 1992. Nafure Gener.1. 345-347. 4. Schellenberg et al, 1992, Science i58,668671.5. MullA et al, 1992, Nalure Gener 2, 340-342. 6. Mullan et al. Neuropsychialric Genetics, 48:129-130. 7. Corderet al. (1993) Science 261,921.
529 CLINICAL AND GENEALOGJC STUDY OF A NEW FAMILIAL ALZHEJMER’S DISEASE (FAD). G. Capocchil, A. Picchiarellil, A.C. Bruni* and G. Macchi3. ‘Institute of Neurology, University of Perugia, Italy, 2S.M.I.D. Center, General Hospital, Lamezia Terme, Italy, 3Jnstitute of Neurology, Catholic University, Rome, Italy. The clinical and genealogical aspects of a family of Calabria origin, at present living in Umbria, affected by late onset have been studied. The family is composed by 151 subjects across 6 generations. 8 subjects have been identified as AD affected, 2 by direct clinical assessment, 2 by analysis of the medical records and 4 by analysis of the medical history. In one case the diagnosis has been confirmed histologically by cortical biopsy. In all affected