Porphobilinogen deaminase in acute intermittent porphyria: activity and concentration in erythrocytes and lymphocytes.
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Acute Disease↗
Biomedical subjects
L Lannfelt
Publications and source records attributed to L Lannfelt.
Genetic heterogeneity of the porphobilinogen deaminase gene in Swedish families with acute intermittent porphyria.
Acute intermittent porphyria (AIP) is an autosomal dominant metabolic disorder affecting the enzyme porphobilinogen (PBG) deaminase in the heme biosynthetic pathway. The highest prevalence of the disorder has been observed in Scandinavia, especially in northern Sweden (Lappland) where it occurs with a prevalence of 1 in 1500. Biochemical assays of the activity and concentration of PBG deaminase in red blood cells, haplotyping with 4 intragenic restriction fragment length polymorphisms (RFLPs) (MspI, PstI, BstNI, ApaLI) using the polymerase chain reaction (PCR) and screening for known base substitutions by oligonucleotide probes was performed in 28 Swedish AIP families. There was no close relationship between haplotype, biochemical findings (PBG deaminase activity, enzyme-linked immunosorbent assay [ELISA], and excess urinary excretion of delta-aminolevulinic acid or PBG), and a specific mutation. Three different haplotypes were identified. The haplotype 2/1/1/2 (MspI/PstI/BstNI/ApaLI; +/-/-/+) was found to be the most frequent among gene carriers (P less than 0.001). The disease segregated with the haplotype 2/1/1/2 in the 10 families originating from northern Sweden. All 28 families were screened for three known point mutations. Only one was found to carry one of these mutations. Thus, the genetic background of AIP is heterogeneous in Sweden.
Alleles↗
Immunological determination of porphobilinogen deaminase as a diagnostic measure in acute intermittent porphyria.
Manifest disease symptoms of acute intermittent porphyria may be provoked by several external factors. Latent gene carriers should be identified at an early stage and informed about preventive measures. Porphobilinogen deaminase activity in red blood cells may be used as one indicator of the carrier state. However, there is an overlap of enzyme activity between healthy controls and carriers of the trait. Thus latent gene carriers cannot always be identified. In the present study a recently reported enzyme-linked immunosorbent assay (ELISA) was used to quantify the concentration of the enzyme porphobilinogen deaminase in erythrocytes in 845 individuals belonging to families with acute intermittent porphyria. Using previous available diagnostic methods 417 of them had been diagnosed as gene carriers, 339 as non-carriers, and 89 were of "uncertain" classification. Of those with "uncertain" diagnosis, 19 had a decreased concentration of porphobilinogen deaminase and could thus be diagnosed as gene carriers. However, 70 cases of the 89 were still "uncertain", which underlines the need for further improvement of the diagnostic methods.
Ammonia-Lyases↗
ELISA for measuring porphobilinogen deaminase in human erythrocytes.
An ELISA method has been developed to quantitate human porphobilinogen deaminase in erythrocyte lysate. The antiserum used in the assay was raised against the erythropoietic form of human porphobilinogen deaminase. The IgG fraction was characterized by use of immunoblotting technique, rocket immunoelectrophoresis and immunotitration and shown to be monospecific. The measuring range of the method was from 4 ng to 50 pg. Intra- and inter-assay coefficients of variation were 6% and 7%, respectively. Erythrocyte lysates from 97 apparently healthy individuals were assayed giving a mean erythrocyte porphobilinogen deaminase protein concentration of 150 +/- 28 SD (micrograms/g Hb) and a specific enzyme activity of 750 +/- 140 SD (nkat/g). Eight patients with acute intermittent porphyria were also investigated. A decreased concentration of enzyme protein, i.e. 84 +/- 13 SD (micrograms/g Hb) with a normal specific activity, was found.
Ammonia-Lyases↗
Mutations in acute intermittent porphyria detected by ELISA measurement of porphobilinogen deaminase.
To study the existence of different mutations in acute intermittent porphyria, erythrocyte porphobilinogen deaminase activity and enzyme protein concentration were investigated in 125 porphyria gene carriers from 31 families, and in 121 apparently healthy controls. Porphobilinogen deaminase concentration (micrograms/gHb) was quantified using a recently developed double-sandwich ELISA. The ratio of enzyme catalytic activity to the concentration of enzyme protein was expressed as the porphobilinogen specific activity (nkat/g). The controls had a mean porphobilinogen deaminase concentration of 160 +/- 35 micrograms/gHb and a specific activity of 762 +/- 127 nkat/g. Two different types of mutation causing acute intermittent porphyria were detected. The majority (91%) of gene carriers, from 25 families, had a diminished porphobilinogen deaminase concentration of 102 +/- 18 micrograms/gHb, with a slightly lowered specific activity of 634 +/- 105 nkat/g. In 9% of the gene carriers, representing six different families, an increase in porphobilinogen deaminase concentration to 269 +/- 46 micrograms/gHb, and a highly significant reduction in specific activity to 234 +/- 48 nkat/g, were found, which indicates the presence of a different mutation.
Ammonia-Lyases↗
Porphobilinogen deaminase in human erythrocytes: purification of two forms with apparent molecular weights of 40 kDa and 42 kDa.
Porphobilinogen deaminase was purified from human erythrocytes by ion-exchange chromatography, gel filtration and hydrophobic interaction chromatography. Two forms of the enzyme were isolated, with apparent molecular weights of 40 kDa and 42 kDa, and in relative amounts of 85% and 15%, respectively. Both forms were found to have an N-terminal amino acid sequence identical to that published for the erythropoietic form of porphobilinogen deaminase, as deduced from a cDNA clone. The two forms present could each be separated into three differently charged subforms by Mono Q chromatography.
Amino Acid Sequence↗
DNA polymorphisms within the porphobilinogen deaminase gene in two Swedish families with acute intermittent porphyria.
Two unrelated families with acute intermittent porphyria (AIP), an autosomal dominant disease related to a defect in porphobilinogen deaminase (PBG-D, EC 4.1.3.8.), were studied with regard to three restriction fragment length polymorphisms (RFLPs) (MspI, PstI, BstNI) within the PBG-D gene. The results indicate that linkage analysis of RFLPs within the gene can be used as a complement to PBG-D analysis for the diagnosis of gene carriers in families with AIP.
Ammonia-Lyases↗
Apolipoprotein E epsilon4 allele, skin vessel reactivity and vascular risk factors in Alzheimer's disease.
The apolipoprotein E (ApoE) epsilon4 allele is strongly associated with Alzheimer's disease (AD), and is, at the same time, a risk factor for cardiovascular disease. Recently, it has also been suggested that skin vessel reactivity is impaired in AD. The aim of this study was to assess the impact of the ApoE epsilon4 allele on the results of skin vessel reactivity tests and vascular risk factors such as cholesterol and blood pressure in AD. Fourteen non-smoking patients, who were in good general health and took no medicines, were tested. Three vasodilating substances with different modes of action, acetylcholine (ACh), isoprenaline and nitroprusside, were iontophoresed into the skin and the resultant vasodilation of the skin vessels was evaluated with the aid of a newly developed laser Doppler perfusion imager. The results of the tests did not differ significantly between the patient group with (n=10) and without (n=4) the ApoE epsilon4 allele, perhaps due to the small number of patients. The results of the skin vessel reactivity tests of the patient subgroups were also compared to those of healthy, non-smoking, non-medicating, age-matched controls. The findings of that comparison suggest, that the presence of the epsilon4 allele in AD might have an impact on skin vessel reactivity to the cholinergic agonist ACh.
Journal Article↗
Abnormalities in Alzheimer's disease fibroblasts bearing the APP670/671 mutation.
Abnormalities in cultured fibroblasts from familial Alzheimer's Disease (FAD) cases uniquely enable the determination of how gene defects alter cell biology in living tissue from affected individuals. The current study focused on measures of calcium regulation and oxidative metabolism in fibroblast lines from controls and FAD individuals with the Swedish APP670/671 mutation. Bombesin-induced elevations in calcium in APP670/671 mutation-bearing lines were reduced by 40% (p < 0.05), a striking contrast to the 100% increase seen in sporadic AD and presenilin-1 (PS1) mutation-bearing cells in previously published studies. The APP670/671 mutation-bearing lines did not exhibit the exaggerated 4-bromo-A23187 releasable pool of calcium following 10 nM bradykinin, the enhanced sensitivity of calcium stores to low concentrations of bradykinin, nor the reduced activity of alpha-ketoglutarate dehydrogenase previously reported in cells from sporadic AD and mutant PS1 FAD. Thus, an altered regulation of internal calcium stores is common to all AD lines, but the calcium pool affected and the polarity of the alteration varies, apparently in association with particular gene mutations. Comparison of signal transduction in cell lines from multiple, genetically characterized AD families will allow testing of the hypothesis that these various pathogenic FAD abnormalities that lead to AD converge at the level of abnormal signal transduction.
Alzheimer Disease↗
Biochemical diagnostic markers to detect early Alzheimer's disease.
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Age of Onset↗
APOE polymorphism and clinical duration determine regional neuropathology in Swedish APP(670, 671) mutation carriers: implications for late-onset Alzheimer's disease.
Neurofibrillary changes throughout the brain were investigated for three relatives who carried the Swedish APP(670, 671) mutation which causes overproduction of Abeta40 and Abeta42. They differed in terms of APOE genotype, age at the onset of dementia, and disease duration (P1: epsilon2/3, age 57, 11 years; P2: epsilon2/3, age 61, 5 years; P3: epsilon4/4, age 44, 12 years). For each subject, paraffin-embedded sections from diverse anatomically and cytoarchitectonically well-preserved regions were stained using the modified Bielschowsky method. Neurofibrillary tangles (NFT) and neuritic plaques (NP) were counted, and the area occupied by plaque estimated (%NP). In addition, sections from the medial frontal gyrus were stained with monoclonal antibodies to APOE. The regional patterns of neurofibrillary changes were consistent with those for late-onset AD. Longer disease duration was associated with further accumulations in earlier-affected areas, with superficial cortical layers consistently containing higher %NP than deep layers. APOE epsilon4/4 was associated with deeper limbic and frontal NFT, with an excess of NP (especially in the outer parietal cortex) which stained heavily for APOE - as well as with very early onset. APP(670, 671) mutation carriers demonstrate regional brain neurofibrillary changes characteristic of late-onset Alzheimer's disease with evidence for more Abeta deposition for epsilon4/4 than epsilon2/3. This raises the possibility that early Braak Stage I-II lesions might also follow this pattern of promotion.
Adult↗
Lack of association between an intronic polymorphism in the presenilin-1 gene and sporadic late-onset Alzheimer disease in Polish patients.
The apolipoprotein E (APOE) gene has in many studies been identified as a susceptibility factor in Alzheimer's disease (AD). The APOE association is rather strong, but other not yet identified genetic factors are assumed to be involved in the pathogenesis of AD. Recently an association between an intronic polymorphism in presenilin-1 (PS-1) gene and late-onset AD was claimed. In order to confirm this observation we studied a sample of Polish patients with sporadic AD. However, our results did not confirm the existence of an association between the intronic polymorphism in the PS-1 gene and late-onset AD.
Age of Onset↗
Apolipoprotein E and alpha1-antichymotrypsin genotypes and age of onset of familial Alzheimer's disease.
Apolipoprotein E (APOE) and alpha1-antichymotrypsin (ACT) genotype and allele frequency distribution were investigated in 113 familial Alzheimer's disease (AD) cases. A significantly higher sigma4 frequency was observed in patients with an age of onset between 55-64 and 65-74 years compared to individuals with later or earlier onset. No difference in ACT A allele frequency was seen in any onset group, nor was any influence of ACT genotypes on the age of onset observed. However, the mean age of onset was lowered by the presence of the ACT/AA and ACT/TT genotypes among APOE sigma3/3 bearers. Possible APOE effects on age of onset were evaluated in 78 affected sib pairs. An earlier age of onset was observed in siblings with an sigma4 allele compared to siblings without an sigma4 allele. This supports the notion that the sigma4 allele promotes an earlier age of onset. However, in siblings with the same APOE genotype, a wide range of onset was seen, indicating that unknown genetic or environmental factors affect the expression of AD.
Adult↗
White matter lesions in Alzheimer patients are influenced by apolipoprotein E genotype.
To analyse the influence of apolipoprotein E (APOE) genotype on the extent of white matter lesions (WMLs) in Alzheimer's disease (AD), we examined 60 AD patients with magnetic resonance imaging. The WMLs were rated visually in different brain regions. The patients with the APOE genotype sigma4/4 had more extensive WMLs in the deep white matter than patients with genotypes sigma3/3 and sigma3/4. There was a correlation with age for WMLs in the deep white matter in patients with the APOE sigma3/3 genotype. In patients carrying at least one sigma4 allele, the WMLs showed no age correlation. The results could imply that in APOE allele sigma4 carriers, the WMLs represent a pathological process related to the aetiology of the disease.
Aged↗
Inheritance of the ApoE epsilon4 allele increases the rate of brain atrophy in dementia patients.
We investigated the influence of the apolipoprotein (ApoE) epsilon4 allele on the rate of brain atrophy in patients with clinical dementia and in subjects at risk for dementia. Eighty-one subjects, consecutively referred to a memory clinic due to symptoms of dementia, went through a comprehensive examination, including cerebral magnetic resonance imaging. After an initial investigation these subjects were divided into one of six diagnostic groups; Alzheimer's disease (AD, n = 23), objective cognitive impairment (OCI, n = 27), subjective cognitive impairment (SCI, n = 17), vascular dementia (VaD), frontotemporal dementia (FTD) and unspecified dementia (USD). The last three groups were joined into one diagnostic group designated 'other dementia' (OD, altogether n = 14). In order to study the progression of cognitive impairment as well as the rate of atrophy in different brain regions all subjects were reinvestigated after an average period of 16 months. Interest was focused on investigating if those subjects with one or two epsilon4 alleles differed in either dementia progression or rate of brain atrophy compared to those without the epsilon4 allele. We found that the ApoE epsilon4 carriers had a statistically significantly larger increase in ventricular volume as compared with the ApoE epsilon4 noncarriers. In all diagnostic groups the ApoE epsilon4 carriers showed a greater rate of ventricular volume increase, as compared to the noncarriers. However, this difference was statistically significant only for the OD subjects. No statistical significant changes over time were seen for whole brain volume or volume of the temporal lobes and the medial temporal lobes. The diagnostic groups differed in dementia progression with the AD subjects having the most pronounced reduction in MMSE scores as compared to subjects at risk for AD (OCI and SCI subjects). The presence of ApoE epsilon4 allele did not influence the change in MMSE in any of the diagnostic groups.
Aged↗
No detected mutations in the genes for the amyloid precursor protein and presenilins 1 and 2 in a swiss early-onset Alzheimer's disease family with a dominant mode of inheritance.
Mutations have been found in more than a hundred early-onset families with Alzheimer's disease (AD) in the genes for the amyloid precursor protein, presenilin 1 and presenilin 2. The object of our investigation was to identify if these mutations or novel ones were operating in a Swiss early-onset AD family (mean age of onset: 53.3 years) with 7 members available, all neuropathologically confirmed. No known or new mutations were detected. Thus, our data support the existence of a yet unknown mutation, or other genes, contributing to familial early-onset AD. CopyrightCopyright 1999S.KargerAG,Basel
Adult↗
Tau immunoreactivity detected in human plasma, but no obvious increase in dementia.
Tau proteins are central to the neuropathology of Alzheimer's disease and tau levels in cerebrospinal fluid are elevated in affected individuals. In this study, we investigated the presence of tau in plasma from subjects with Alzheimer's disease (n = 16), frontotemporal dementia (n = 10), vascular dementia (n = 16) and from healthy controls (n = 15). By using an ELISA with monoclonal tau antibodies, tau immunoreactivity was detected in approximately 20% of the subjects. However, no difference between the disease and control groups was seen. After gel filtration of tau immunopositive plasma, the peak reactivity was found in the 160-kD fraction, indicating the source to be tau-like molecules of high-molecular-weight or polymers of low-molecular-weight tau isoforms. We conclude that measurements of tau in plasma cannot be utilized diagnostically for Alzheimer's disease or for the other dementias investigated. Copyrightz1999S.KargerAG,Basel
Aged↗
Decreased plasma insulin-like growth factor-I level in familial Alzheimer's disease patients carrying the Swedish APP 670/671 mutation.
The plasma insulin-like growth factor I (IGF-I) level was determined in family members carrying the Swedish amyloid precursor protein (APP) 670/671 mutation with or without Alzheimer's disease (AD) and in age-matched controls from the same family. Plasma growth hormone (GH) and prolactin (PRL) levels were also determined. Measurement of the plasma IGF-I level by radioimmunoassay revealed a significant reduction only in the family members with AD compared to age-matched controls. However, there was no significant difference in the levels of GH and PRL between the mutation carriers with or without AD and their respective age-matched controls. These findings indicate that the mechanism(s) regulating GH and PRL were preserved and those regulating IGF-I levels might be affected in AD patients with the Swedish APP 670/671 mutation. CopyrightCopyright 1999S.KargerAG, Basel
Aged↗