Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have discovered a single homoallelic nucleotide substitution as the putative cause of the perinatal (lethal) form of hypophosphatasia in Canadian Mennonites. Previous linkage and haplotype analysis in this population suggested that a single mutational event was responsible for this autosomal recessive form of hypophosphatasia. The mutation is a guanosine-to-adenosine substitution at nucleotide position 1177 in exon 10 of the tissue nonspecific (liver/bone/kidney) alkaline phosphatase gene. This Gly317-->Asp mutation segregates exclusively with the heterozygote phenotype we previously assigned by biochemical testing (maximum combined lod score of 18.24 at theta = 0.00). This putative disease-causing mutation has not been described in controls nor in other non-Mennonite probands with both lethal and nonlethal forms of hypophosphatasia studied to date. This Gly317-->Asp mutation changes a polar glycine to an acidic aspartate at amino acid position 317 within the highly conserved active site region of the 507-amino-acid polypeptide. Carrier screening for this lethal mutation in our high-risk population is now feasible.
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PMID:A homoallelic Gly317-->Asp mutation in ALPL causes the perinatal (lethal) form of hypophosphatasia in Canadian mennonites. 840 53

Hypophosphatasia, an inheritable metabolic disorder affecting calcification, has been shown to have various oral manifestations. Recently, it was suggested that it may serve as a predisposing factor in the pathogenesis of early-onset periodontitis. The present study was designed to examine the frequency of hypophosphatasia among patients with juvenile periodontitis and rapidly progressive periodontitis. Eighteen patients, nine females and nine males (age 19-37 years, mean 23.2 years), were included in this study. Venous blood and urinary samples were collected and assayed for alkaline phosphatase and urinary phosphoethanolamine. Mean alkaline phosphatase levels (109 +/- 35 IU/L) were within the normal limits for all patients except one who exhibited slightly lower than normal values. Urinary phosphoethanolamine, a typical marker of hypophosphatasia, was absent from all specimens, which rules out the possible diagnosis of such disorder in these patients. Until more information is available, the role of hypophosphatasia as a predisposing factor in early-onset periodontitis is yet to be established.
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PMID:Lack of evidence for hypophosphatasia as a factor in the pathogenesis of early-onset periodontitis. 853 Dec 51

Hypophosphatasia is a rare (1/100,000), inherited inborn error of metabolism characterized by low serum and tissue alkaline phosphatase activities resulting in skeletal abnormalities. Four clinical forms are recognized depending on the age of diagnosis. Since treatment is not available and the prognosis is always lethal, detection of index cases and prenatal diagnosis is subsequent pregnancies is very important. Here we report a case with the most severe form of hypophosphatasia associated with lung hypoplasia.
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PMID:Neonatal form of hypophosphatasia. A case report. 856 Jun 13

We successfully assessed a fetus at risk for lethal infantile hypophosphatasia using amniocyte DNA and allele-specific oligonucleotide (ASO) probes for two missense mutations in the tissue-non-specific alkaline phosphatase isoenzyme (TNSALP) gene. The nucleotide changes had been discovered in a sister who died at 8 months of age from this inborn error of metabolism. The mother was known to carry the 747 (cDNA) G-->A transition, whereas her husband and 5-year-old daughter, who were also healthy, carried the 1309 A-->T transversion. Amniocytes, obtained at 16 weeks' gestation, provided genomic DNA for polymerase chain reaction (PCR) amplification of the appropriate TNSALP gene exons. ASO hybridization revealed absence of the 747A mutation and presence of the 1309T base changes in the fetus, indicating a carrier for hypophosphatasia. At 8 months of age, the offspring was in excellent health and without any radiological evidence of skeletal disease. His serum ALP activity and plasma pyridoxal 5'-phosphate level were decreased and increased, respectively, at levels consistent with the prenatal assessment. The ASO studies were confirmed postnatally using peripheral blood leukocyte DNA. This is the first application of direct mutational analysis to assess a fetus at risk for hypophosphatasia.
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PMID:Infantile hypophosphatasia: successful prenatal assessment by testing for tissue-non-specific alkaline phosphatase isoenzyme gene mutations. 860 78

The markedly variable clinical expressivity of hypophosphatasia was explored by examining biochemical properties of alkaline phosphatase (ALP) in fibroblasts cultured from 16 patients with severe autosomal recessive forms of this metabolic bone disease. Outcome ranged from death in utero to survival into childhood. Mean ALP activity in patients was 4.3% of controls. Gel filtration analysis indicated a mixture of dimeric and tetrameric ALP in both subject groups. Control cells produced levels of bone ALP cross-reacting material that correlated strongly with ALP activity. Patient bone ALP cross-reacting material levels averaged 41% of the control mean with a wide range of individual values that did not correlate with ALP activity. Control ALP activity was stable in 3% SDS and during electrodialysis. Patient ALP activity was generally unstable under both conditions but with a considerable range of individual values. Fibroblast ALP from every patient exhibited some aberrancy in physicochemical and immunoreactive properties. These data strongly correlated (r = 0.95) with clinical severity. There appeared to be specific associations of tissue nonspecific (bone/liver/kidney isoenzyme) ALP (TNSALP) gene mutations with aberrant enzyme properties and disease severity. We conclude that a spectrum of aberrant biochemical properties of the TNSALP enzyme, caused by different combinations of TNSALP gene missense mutations, reflects the variable clinical expressivity of hypophosphatasia.
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PMID:Aberrant properties of alkaline phosphatase in patient fibroblasts correlate with clinical expressivity in severe forms of hypophosphatasia. 867 82

Hypophosphatasia is a rare inherited metabolic disease characterised by reduced plasma and tissue alkaline phosphatase activity, and may present in infancy, childhood or adulthood. The differing modes of inheritance, presentation and natural history are likely to reflect variable expression of the alkaline phosphatase gene defect. A case of infantile hypophophatasia presenting with hypercalcaemia is described and the histological and radiological resolution of the mineralisation defect present initially are reported.
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PMID:Hypophosphatasia. 888 24

Hypophosphatasia is associated with a defect of the tissue-non-specific alkaline phosphatase gene. We performed a mutational analysis in a surviving patient diagnosed at birth as having hypophosphatasia, on the basis of a low level of serum alkaline phosphatase (ALP) activity and characteristic radiographical findings. She had two sisters, one of whom died of respiratory failure complicated by perinatal hypophosphatasia; the other seemed healthy, with a relatively low activity level of ALP. The patient's parents also had low ALP activity. Sequence analysis of the tissue-nonspecific alkaline phosphatase gene was performed, using genomic DNA and total RNA from the skin fibroblasts of the patient and the peripheral mononuclear cells of her parents. The conversion of Phe to Leu at codon 310 (F310L) and Gly to Arg at 439 (G439R) were identified in the patient. Interestingly, the reconstructive experiments demonstrated that the F310L mutant exhibited an ALP activity level 65% of the normal level, whereas the mutant G439R had no activity. Moreover, the digestion by StuI, after a PCR using complementary DNA extracted from fibroblasts of the patient and lymphocytes of her father, revealed a relatively low messenger RNA level of F310L. These findings suggest that the neonatal case of hypophosphatasia was associated with compound mutations, one of which caused the loss of ALP activity and the other of which caused a slight reduction of the ALP activity, with a relatively low level of messenger RNA.
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PMID:Identification of novel missense mutations (Phe310Leu and Gly439Arg) in a neonatal case of hypophosphatasia. 895 59

Hypophosphatasia is a rare metabolic bone disease characterized biochemically by deficient enzymatic activity of the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). All isoforms of TNSALP (e.g. bone and liver TNSALP), apparently differing only by posttranslational modifications, are affected. To explore the biochemical basis and extremely variable severity of hypophosphatasia, we used 2-site immunoradiometric assays that quantify in serum either 1) bone TNSALP (iBALP) alone, or 2) both bone and liver TNSALP (iTNSALP). Sera from 33 patients in 26 kindreds reflecting all 6 clinical types of the disorder were studied. In every patient, except the two with pseudohypophosphatasia, serum iBALP and iTNSALP levels were decreased compared to age-appropriate control ranges. The magnitude of the decrease in iBALP and iTNSALP levels correlated with clinical severity. The mean ratio of iBALP or iTNSALP level to total ALP activity was unremarkable for the mild childhood, adult, and odonto forms of hypophosphatasia. For the severe perinatal and infantile forms, the mean ratios were low. If our finding of reduced iBALP levels in the circulation reflects a similar abnormality in the skeleton, the pathogenesis of hypophosphatasia could involve decreased amounts of extracellular TNSALP in bone and cartilage. How TNSALP gene mutations affect the enzyme and cause skeletal disease requires further investigation.
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PMID:Hypophosphatasia: levels of bone alkaline phosphatase immunoreactivity in serum reflect disease severity. 896 42

We report the inactivation, via homologous recombination, of two of the three active mouse alkaline phosphatase genes, i.e., embryonic (EAP) and tissue nonspecific (TNAP). Whereas expression of the EAP isozyme was abolished in all tissues that express EAP developmentally (such as the preimplantation embryo, thymus, and testis), the EAP knock-out mice show no obvious phenotypic abnormalities. They reproduce normally and give birth to live offspring, indicating the nonessential role of EAP during embryonic development. Mice deficient in the TNAP gene mimic a severe form of hypophosphatasia. These TNAP-/- mice are growth impaired, develop epileptic seizures and apnea, and die before weaning. Examination of the tissues indicates abnormal bone mineralization and morphological changes in the osteoblasts, aberrant development of the lumbar nerve roots, disturbances in intestinal physiology, increased apoptosis in the thymus, and abnormal spleens. Our results indicate that, in the mouse, TNAP appears not to be essential for the initial events leading to bone mineral deposition but that TNAP seems to play a role in the maintenance of this process after birth. The other phenotypic manifestations may be a consequence of the lack of TNAP in the developing neural tube between stages E8.5 and E13.5 of embryogenesis. We hypothesize that the autonomic nervous system is compromised in these TNAP-/- mice.
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PMID:Inactivation of two mouse alkaline phosphatase genes and establishment of a model of infantile hypophosphatasia. 905 46

This chapter summarizes the many recent advances in our understanding of the principal heritable disorders of bone. In the course of little more than a decade many diseases that were recognizable only by their clinical and radiological features have become explicable in molecular terms. Large numbers of mutations of the genes coding for collagen, for alkaline phosphatase, for the cell surface receptors for parathyroid hormone and for calcium, and for a number of other proteins, are recognized. The chapter covers the many variants of osteogenesis imperfecta, the most common heritable cause of fractures. It also covers osteopetrosis, hypophosphatasia, pseudohypoparathyroidism (with Albright's hereditary osteodystrophy), familial benign hypercalcaemia, autosomal dominant hypocalcaemia and the molecular causes of some chondrodysplasias.
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PMID:Osteogenesis imperfecta and other heritable disorders of bone. 922 92


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