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Biomedical subjects

A Gal

Publications and source records attributed to A Gal.

At least 73 records · Page 4Linked to original sources
PubMed1998

Prenatal diagnosis of carbamoyl phosphate synthetase I deficiency by identification of a missense mutation in CPS1.

Carbamoyl phosphate synthetase I (CPS1) deficiency is an autosomal recessive metabolic disorder affecting the first enzymatic step of urea cycle. We report a consanguineous family in which the index patient died at 11 days of age from a severe form of CPS1 deficiency. Initial diagnosis was based on clinical histopathological, and enzymatic investigations. Direct sequencing of the complete CPS1 coding region revealed a disease-associated homozygous Thr544Met mutation in CPS1. On the basis of the molecular data, prenatal diagnosis was established for genomic DNA and performed at gestational week 12, after chorionic villus sampling. The fetus was homozygous for the Thr544Met mutation, and termination of pregnancy was elected. Histopathological signs of the hepatocellular metabolic disorder similar to that of the index patient were found in fetal liver thus giving morphological evidence for this hereditary error of urea cycle function as early as gestational week 12.

Base Sequence↗
PubMed1998

[Adrenoleukodystrophy and adrenomyeloneuropathy. Clinical biochemical and molecular genetic findings].

Adrenoleukodystrophy (ALD) is an X-linked peroxisomal disease affecting 1 in 20,000 males either as cerebral ALD in childhood or as adrenomyeloneuropathy (AMN) in adulthood. Recently, the ALD gene has been identified by positional cloning. We report three males patients with AMN and a fourth patient with juvenile ALD. Biochemical studies showed elevated plasma concentration of saturated very-long-chain fatty acids. Genomic DNA of the patients was analysed for possible sequence variations in the ALD gene by PCR amplification and single strand conformation polymorphism analysis. Three missense mutations (Ser515Phe, Glu267Lys and Arg401Trp) and a 9-bp deletion were detected predicting, respectively, the replacement and absence of amino acids in the deduced amino acid sequence of the ALD protein. In the patients' families, detection of the respective mutations allows the identification of carriers of ALD/AMN. Mutational screening in ALD families is of practical importance in improving genetic counseling.

ATP Binding Cassette Transporter, Subfamily D, Mem↗
PubMed1998

Refined genetic mapping of autosomal dominant retinitis pigmentosa locus RP18 reduces the critical region to 2 cM between D1S442 and D1S2858 on chromosome 1q.

Linkage analysis was performed on a large Danish family to refine the position of RP18, the locus for autosomal dominant retinitis pigmentosa, mapped previously between D1S534 and D1S305 in chromosome 1p13-q21. We genotyped the family members for five microsatellite-type DNA polymorphisms and mapped RP18 between D1S422 and D1S2858 to a region of less than 2 cM. No obvious candidate gene has yet been assigned to the chromosomal interval defined here.

Adult↗
PubMed1998

[Type I lattice corneal dystrophy. Clinical and molecular genetic study of a large family].

BACKGROUND: Lattice corneal dystrophy type I is one of the frequent forms of stromal dystrophies following autosomal dominant inheritance. The beta-IG-h3 gene encoding keratoepithelin on the long arm of chromosome 5 has recently been described as disease gene for lattice corneal dystrophy type I as well as for three other corneal dystrophies with autosomal dominant pattern of inheritance. PATIENTS AND METHODS: Ten family members in three generations of a large family with autosomal dominant lattice corneal dystrophy were analyzed clinically by slit-lamp biomicroscopy. Mutation analysis in the beta-IG-h3 gene was carried out at the mRNA level by RT-PCR and cDNA sequencing. RESULTS: A heterozygous single-base substitution (417C-->T) in exon 4 of the beta-IG-h3 gene was detected predicting the replacement of arginine-124 by cysteine. Analysis of 10 family members showed perfect cosegregation of the mutation and lattice corneal dystrophy type I. The investigation excluded this mutation in one family member previously classified as potentially affected. CONCLUSIONS: The investigation confirmed autosomal dominant inheritance with complete penetrance in the family described. The mutation 417C-->T has already been found earlier in another family of different geographic origin. These results suggest a mutation hot spot at position 417. In addition, no evidence of genetic heterogeneity of lattice corneal dystrophy type I was detected. Molecular genetic analysis (in conjunction with genetic counselling) therefore may be useful in routine diagnostics as the confirmation of the diagnosis by histological examination is possible only after keratoplasty. The common pathomechanism in lattice corneal dystrophy type I may facilitate development of new therapeutic concepts; the easy accessibility of the target organ may provide new possibilities e.g. for gene therapy.

Adult↗
PubMed1998

Etheno adducts in spleen DNA of SJL mice stimulated to overproduce nitric oxide.

In order to investigate specific DNA damage caused by nitric oxide (NO) induced lipid peroxidation, levels of promutagenic etheno adducts 1,N6-ethenodeoxyadenosine (epsilondA) and 3,N4-ethenodeoxycytidine (epsilondC) were measured in spleen DNA of SJL mice induced to produce high levels of NO by injection of RcsX (pre-B-cell lymphoma) cells. epsilondA and epsilondC levels were quantified by an ultrasensitive immunoaffinity-32P-post-labeling method. Spleen DNA of control mice (n = 5) had background levels of 9.2+/-5.4 epsilondA adducts per 10(9) dA and 13.1+/-5.7 epsilondC adducts per 10(9) dC. In RcsX cell-injected mice (n = 7), levels of these adducts were elevated approximately 6-fold, i.e. 53.9+/-39.4 epsilondA per 10(9) dA and 83.5+/-57.8 epsilondC per 10(9) dC (P < 0.05). Mice injected with RcsX cells and also treated with NG-methyl-L-arginine (NMA), an inhibitor of inducible nitric oxide synthase (n = 6), had significantly reduced levels (P < 0.05) of both epsilondA and epsilondC (13.5+/-5.7 epsilondA per 10(9) dA and 28.2+/-15.7 epsilondC per 10(9) dC). These findings constitute the first available evidence of formation of etheno adducts associated with NO overproduction in vivo. The adducts were presumably formed from lipid peroxidation products such as trans-4-hydroxy-2-nonenal (HNE), generated via oxidation of lipids by peroxynitrite. The results suggest that etheno-DNA adducts, among other types of damage, may contribute to the etiology of cancers associated with chronic infection/inflammation in which NO is overproduced.

Aldehydes↗
PubMed1998

Autosomal dominant medullary cystic kidney disease: evidence of gene locus heterogeneity.

Autosomal dominant medullary cystic kidney disease (ADMCKD; synonym: medullary cystic disease, MCD) is an autosomal dominant kidney disorder, sharing morphological and clinical features with recessive juvenile nephronophthisis (NPH), such as reduced urinary concentration ability and multiple renal cysts at the corticomedullary junction. While in NPH end-stage renal disease (ESRD) occurs in adolescence, ADMCKD leads to ESRD in adulthood. Recently a gene locus for ADMCKD has been localized to chromosome 1q21 in two large Cypriot families. This prompted us to examine linkage in three ADMCKD-families, using the same set of polymorphic microsatellite markers spanning the critical region on chromosome 1q21. Haplotype analysis revealed that none of the three families showed linkage to this locus, thus demonstrating evidence for genetic locus heterogeneity. Additional linkage analysis studies need to be performed in order to identify further gene loci cosegregating with this autosomal dominant kidney disorder.

Adult↗
PubMed1997

Characterization of canine rod photoreceptor cGMP-gated cation channel alpha-subunit gene and exclusion of its involvement in the hereditary retinal dystrophy of Swedish Briards.

The nucleotide sequence of the canine rod photoreceptor cGMP-gated cation channel alpha-subunit (cCNCG1) cDNA has been determined. The open reading frame consists of 2073 nucleotides, which encode a putative protein of 691 amino acids. In addition, we have established the exon/intron boundaries of the cCNCG1 gene and determined the complete sequence of six introns of a total of eight. The exon/intron organization (location and length of exons and introns) of the cCNCG1 gene is very similar to that of the human rod photoreceptor cGMP-gated cation channel alpha-subunit gene. We used single-strand conformation polymorphism analysis to search for potential pathogenic sequence changes in the cCNCG1 gene in a Swedish Briard and Briard-Beagle dog kindred, in which an autosomal recessive retinal dystrophy is segregating, a disease which shows phenotypic similarities to retinitis pigmentosa, a heterogeneous group of hereditary and progressive retinal degeneration in human. In intron 3, we found several DNA polymorphisms, which do not cosegregate with the affected status of the dogs, thus excluding cCNCG1 as a candidate gene for the retinal dystrophy in this strain of Swedish Briards.

Amino Acid Sequence↗
PubMed1997

Molecular analysis of the L1CAM gene in patients with X-linked hydrocephalus demonstrates eight novel mutations and suggests non-allelic heterogeneity of the trait.

Eight novel mutations were identified in the gene encoding L1CAM, a neural cell adhesion protein, in patients/families with X-linked hydrocephalus (XHC) providing additional evidence for extreme allelic heterogeneity of the trait. The two nonsense mutations (Gln440Ter and Gln1042Ter) result most likely in functional null-alleles and complete absence of L1CAM at the cell surface. The four missense mutations (Leu482Pro, Ser542Pro, Met741Thr, and Val752Met) as well as delSer526 may considerably alter the structure of L1CAM. Interestingly, a missense mutation in an XHC family predicting the Val768Ile change in the second fibronectin type III domain of L1CAM was found not only in the two affected cousins and their obligate carrier mothers but also in two unaffected male relatives of the patients. Several possible explanations of this finding are discussed; the most likely being that Val768Ile is a rare non-pathogenic variant. If this were indeed the case, our data suggest that the XHC in this family is not due to a mutation of the L1CAM gene, i.e., that, in addition to the extreme allelic heterogeneity of XHC, a non-allelic form of genetic heterogeneity may also exist in this trait.

Alleles↗
PubMed1997

Nitrotyrosine formation, apoptosis, and oxidative damage: relationships to nitric oxide production in SJL mice bearing the RcsX tumor.

In SJL mice, growth of RcsX lymphoma cells results in activation of macrophages in the spleen and lymph nodes to produce high levels of NO radical (NO.). We used this experimental model system to study the toxicology of NO. in vivo. To characterize spatial relationships between sites of NO. production and tissue damage, immunohistochemical techniques were developed for simultaneous detection of inducible NO. synthase (iNOS), 3-nitrotyrosine, and apoptosis in spleen and lymph nodes of tumor-bearing animals. Elevated expression of iNOS, presumed to reflect increased NO. production, was associated with a significant increase in frequency of apoptotic nuclei. Both apoptotic nuclei and 3-nitrotyrosine staining were found in cells juxtaposed to iNOS-expressing (ie., NO.-producing) macrophages and also within the macrophages themselves. To assess the extent of DNA damage associated with the response, 8-oxoguanine levels were quantified in DNA extracted from spleens of tumor-bearing mice. No increase in levels of this marker of oxidative DNA damage was found in tissues in which apoptosis and 3-nitrotyrosine levels were highly elevated within specific subsets of cells. Collectively, our results indicate that under the pathophysiological conditions existing in the RcsX tumor-bearing SJL mouse, cellular damage caused by NO. and/or other reactive species produced by activated macrophages is highly localized within cells in close proximity to the activated macrophages.

Animals↗
PubMed1997

Identification of 31 novel mutations in the N-acetylgalactosamine-6-sulfatase gene reveals excessive allelic heterogeneity among patients with Morquio A syndrome.

Mutation analysis of the N-acetylgalactosamine-6-sulfate sulfatase gene was performed in a group of 35 patients with mucopolysaccharidosis type IVA from 33 families, mainly of European origin. By nonradioactive SSCP screening, 35 different gene mutations were identified, 31 of them novel. Together they account for 88.6% of the disease alleles of the patients investigated. The vast majority of the gene alterations proved to be point mutations, 23 missense, 2 nonsense, and 3 affecting splicing. Six small deletions (1-27 bp) and one insertion were also characterized. In a Polish family, two mildly affected siblings were compound heterozygotes for R94G and R259Q. Their mother was homozygous for the latter point mutation, leading to enzyme deficiency and a borderline disease phenotype.

Adolescent↗
PubMed1997

Identification of 16 sulfamidase gene mutations including the common R74C in patients with mucopolysaccharidosis type IIIA (Sanfilippo A).

Mucopolysaccharidosis type IIIA (MPS IIIA or Sanfilippo A disease) is a storage disorder caused by deficiency of the lysosomal enzyme sulfamidase. Mutation screening, using SSCP/heteroduplex analyses on cDNA and genomic DNA fragments, was performed in a group of 42 European patients. Sixteen of the 17 different gene mutations characterized have not been previously described. The spectrum of gene lesions consists of two 1-bp deletions (1091delC, 1093delG), an 18-bp duplication (421ins18), a splice site mutation (IVS2-2A-->G), and 13 different missense point mutations. As in other lysosomal storage disorders, the phenotypic heterogeneity is associated with a considerable genetic heterogeneity. The missense mutation R74C, which alters an evolutionary conserved amino acid in the active site of the enzyme, was found on 56% of alleles of 16 Polish patients, whereas it was less frequent among German patients (21% of disease alleles). R245H, a previously reported common mutation, represents 35% of disease alleles in German patients, but only 3% in Polish patients. As the combined frequency of the common mutations (R74C and R245H) in German and Polish populations exceeds 55%, screening for these two mutations will assist molecular genetic diagnosis of MPS IIIA and allow heterozygote testing in these populations.

Binding Sites↗
PubMed1997

A mechanistic analysis of nitric oxide-induced cellular toxicity.

Nitric oxide (NO.)-induced toxicity was investigated in two different cell lines, Chinese hamster ovary (CHO-AA8) and human lymphoblastoid (TK6), over a range of NO. doses (0-9 mM) delivered for an exposure of 2 h. To determine both short-term and delayed effects leading to death, a range of assays was employed to decipher the major mechanisms of cytotoxicity. Examples of damage parameters measured in this study include inhibition of DNA synthesis, damage to mitochondria, loss of cell membrane integrity, apoptosis, changes in cell cycle distribution, and the occurrence of DNA strand breaks. Our results indicate that NO.-induced toxicity is an extremely complex process involving multiple pathways generally leading to apoptotic cell death. Results consistently demonstrate that TK6 cells are much more susceptible to NO.-induced toxicity than CHO-AA8 cells. This difference in sensitivity could be seen for all types of cellular damage examined. The earliest observable effect of NO. exposure is inhibition of DNA synthesis which is not the result of inhibition of ribonucleotide reductase but may be the result of DNA damage leading ultimately to cell cycle arrest.

Animals↗
PubMed1997

Ocular findings in patients with autosomal dominant retinitis pigmentosa and Cys110Phe, Arg135Gly, and Gln344stop mutations of rhodopsin.

This report describes ocular findings obtained in four patients from three families with autosomal dominant retinitis pigmentosa (adRP) due to missense mutations in the rhodopsin gene. Phenotypes were characterized by standard ophthalmologic examinations, visual fields, electroretinography (ERG), dark adaptation, and two-color dark-adapted threshold perimetry. Two patients aged 38 and 45 years, respectively, from a family with the Cys110Phe mutation showed mild fundus changes without bone spicules as well as small arcuate scotomas in the inferior quadrants of their visual fields but displayed severe functional loss of rods and cones in the ERG. Two-color dark-adapted threshold perimetry revealed a regional type of degeneration. A 48-year-old patient with an Arg135Gly mutation had typical RP with concentrically narrowed visual fields and nondetectable ERG responses. Central visual functions were well preserved for a long time. Two-color dark-adapted threshold perimetry indicated a diffuse type of retinal degeneration. An 18-year-old patient with a Gln344stop mutation has been followed for 13 years. His ERG was clearly reduced at the age of 5 years; since that time, disease progression has been very slow. Currently, there are relatively mild alterations in visual acuity, rod sensitivity, and visual fields. Our findings confirm that there is a large phenotypic variety among patients with adRP and different rhodopsin mutations.

Adolescent↗
PubMed1997

Mutations in RPE65 cause autosomal recessive childhood-onset severe retinal dystrophy.

Autosomal recessive childhood-onset severe retinal dystrophy (arCSRD) designates a heterogeneous group of disorders affecting rod and cone photoreceptors simultaneously. The most severe cases are termed Leber congenital amaurosis (LCA), while the less aggressive forms are usually considered juvenile retinitis pigmentosa. Recently, mutations in the retinal-specific guanylate cyclase gene were found in patients with LCA. Disease genes implicated in other forms of arCSRD are expected to encode proteins present in the neuroretina or in the retinal pigment epithelium (RPE). The RPE, a monolayer of cells separating the vascular-rich choroid and the neuroretina, is in intimate contact with the outer segments of rods and cones via the microvilli surrounding the photoreceptors. The RPE expresses a tissue-specific and evolutionarily highly conserved 61 kD protein (RPE65) present at high levels in vivo. Although the function of RPE65 is not yet known, an important role in the RPE/photoreceptor vitamin-A cycle is suggested by the fact that RPE65 associates both with serum retinol-binding protein and with the RPE-specific 11-cis retinol dehydrogenase, an enzyme active in the synthesis of the visual pigment chromophore 11-cis retinal. Here we report that the analysis of RPE65 in a collection of about 100 unselected retinal-dystrophy patients of different ethnic origin revealed five that are likely to be pathogenic mutations, including a missense mutation (Pro363Thr), two point mutations affecting splicing (912 + 1G-->T and 65 + 5G-->A) and two small re-arrangements (ins144T and 831del8) on a total of nine alleles of five patients with arCSRD. In contrast to other genes whose defects have been implicated in degenerative retinopathies, RPE65 is the first disease gene in this group of inherited disorders that is expressed exclusively in the RPE, and may play a role in vitamin-A metabolism of the retina.

Age of Onset↗
PubMed1997

Isolation of canine retinal arrestin cDNA and exclusion of three candidate genes for Swedish Briard retinal dystrophy.

PURPOSE: Mutations of genes encoding various retina-specific proteins are known to cause a wide spectrum of inherited retinal dystrophies in different species. In the canine, several types of genetic retinal dystrophies have been described affecting primarily the photoreceptors and/or the retinal pigment epithelium. We are performing a systematic analysis of canine candidate genes for such diseases to identify the one mutated in the retinal dystrophy in Swedish Briard dogs. METHODS: We isolated and characterised the full length cDNA of canine retinal arrestin by the method of rapid amplification of cDNA ends (RACE). RESULTS: The full length cDNA isolated by us is 1,575 base pairs (bp) long and contains a 1,218 bp-long open reading frame. CONCLUSIONS: The homology of the canine arrestin protein is highest with the human analogue (88.9%) and lowest with mouse arrestin (85.3%). The most obvious sequence differences among the different arrestins are in the extreme carboxyl terminus. PCR-SSCP (single strand conformation polymorphism) analysis and direct sequencing of retinal cDNA didn't provide any evidence that mutations in the canine arrestin gene are responsible for the retinal dystrophy seen in the Swedish strain of Briard dogs. Similar data were obtained for the genes encoding rhodopsin and the beta-subunit of photoreceptor-specific phosphodiesterase by segregation analysis.

Amino Acid Sequence↗
PubMed1997

Oguchi disease: phenotypic characteristics of patients with the frequent 1147delA mutation in the arrestin gene.

OBJECTIVE: To characterize clinical features of patients with Oguchi disease associated with a homozygous deletion of adenine at nucleotide 1147 (1147delA) in codon 309 in the arrestin gene. METHODS: Mutation screening by single-strand conformation polymorphism analysis was done, followed by sequencing. Ophthalmologic testing included evaluation of visual acuity and color vision, fundus examination, electroretinography, fluorescein angiography, evaluation of kinetic visual field, and dark adaptometry. Nine patients with Oguchi disease from seven unrelated families and family members who were unaffected by the disease were examined. RESULTS: A homozygous 1147delA mutation in the arrestin gene was identified in eight patients from six families with Oguchi disease. All patients who were examined exhibited a golden-yellow retinal reflex associated with Mizuo-Nakamura phenomenon and impairment of rod function in dark adaptation tests, although fundus examination showed slight variation in these findings. Four patients with the mutation had slightly reduced visual acuity, and the electroretinograms of three patients showed slightly reduced amplitudes during 30-Hz flicker electroretinography. CONCLUSION: Patients with Oguchi disease associated with the arrestin 1147delA mutation typically demonstrate retarded rod adaptation, whereas some patients have slightly impaired cone function.

Adolescent↗