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A Sahota

Publications and source records attributed to A Sahota.

At least 55 records · Page 3Linked to original sources
PubMed1994

Identification of a 7-basepair deletion in the adenine phosphoribosyltransferase gene as a cause of 2,8-dihydroxyadenine urolithiasis.

We describe a family of Turkish origin with adenine phosphoribosyltransferase (APRT) deficiency and renal stone disease. The proband had 2,8-dihydroxyadenine urolithiasis but an older sister, who was also deficient in enzyme activity, is so far asymptomatic. The proband was homozygous for a 7-bp deletion in exon 3 of the APRT gene. One allele from each of the parents also contained this deletion. The patient and her father were homozygous for an intragenic TaqI RFLP (1.25-kb fragment) whereas the mother was heterozygous (1.25- and 1.91-kb fragments), indicating that the mutation was present on the allele carrying the 1.25 kb TaqI fragment. The deletion alters the reading frame downstream of codon 93 and would be expected to abolish enzyme activity.

Adenine↗
PubMed1993

Adenine phosphoribosyltransferase deficiency with renal deposition of 2,8-dihydroxyadenine leading to nephrolithiasis and chronic renal failure.

Homozygous adenine phosphoribosyltransferase deficiency is a genetic defect that is associated with 2,8-dihydroxyadenine urolithiasis. Since the prevalence of the heterozygous state is found in 0.4% to 1.2% of the population, it is surprising that more cases of 2,8-dihydroxyadenine urolithiasis have not been reported. Herein we describe a patient with complete adenine phosphoribosyltransferase deficiency with 2,8-dihydroxyadenine urolithiasis leading to chronic renal failure. Gene sequencing revealed that the patient is a compound heterozygote. One of the mutations (a T insertion between bases 346 and 347) has been encountered before, but the second (a G-to-A substitution at base 1356) has not been previously reported. Possible explanations for the unexpected rarity of 2,8-dihydroxyadenine urolithiasis are discussed.

Adenine↗
PubMed1993

Analysis of germline and in vivo somatic mutations in the human adenine phosphoribosyltransferase gene: mutational hot spots at the intron 4 splice donor site and at codon 87.

We have characterized 18 germline and 10 in vivo somatic mutations in the human adenine phosphoribosyltransferase (APRT) gene. Both germline and in vivo somatic mutations were clustered at the intron 4 splice donor site and at codon 87. In vitro somatic mutations in human APRT do not appear to show this clustering. These findings suggest that the spectrum of germline mutations in APRT may be similar to that incurred by somatic cells in vivo, but different from that seen in cultured cells. Thus, in vivo, rather than in vitro, somatic mutations in this gene may be more representative of mutational events occurring in the germline.

Adenine Phosphoribosyltransferase↗
PubMed1993

Resting metabolic rate in homozygous sickle cell disease.

The resting metabolic rate in 20 patients with homozygous sickle cell (SS) disease was 19% higher than in 20 age- and sex-matched control subjects with a normal hemoglobin genotype (AA). The difference was not accounted for by differences in lean body mass. It is postulated that this increased energy expenditure reflects the energy expenditure of erythropoietic hyperplasia and leads to a marginal nutritional state that may contribute to the abnormal growth in SS disease.

Adolescent↗
PubMed1991

Mutational basis of adenine phosphoribosyltransferase deficiency.

The mutational basis of APRT deficiency was studied in non-Japanese and Japanese patients. Fifteen different mutations have been identified altogether. Of these 4 were common, 6 were located in exon 3, and two at the exon 4-intron 4 junction. The common mutations were a missense mutation in exon 3 (asp65----val) and a T insertion at the exon 4-intron 4 junction in non-Japanese patients, a nonsense mutation in exon 3 (trp98----end) in Type I Japanese patients, and an exon 5 missense mutation (met136----thr) in Type II patients. The other mutations in Type I patients consisted mainly of single base changes and small deletions.

Adenine Phosphoribosyltransferase↗
PubMed1991

Transduction of the CHO aprt gene into mouse L cells using an adeno-5/APRT recombinant virus.

An adenovirus-5 recombinant virus Adapt1 carrying the Chinese hamster ovary (CHO) adenine phosphoribosyltransferase (aprt) gene was constructed by insertion of a 2.5-kb fragment containing the complete CHO aprt structural gene linked to a Moloney murine sarcoma virus (MSV) promoter into the E3 region of adenovirus-5. The CHO aprt gene was in the opposite orientation to the adenovirus E3 promoter. Mouse Lapt- tk- (LAT) cells expressed the CHO aprt gene when infected with the virus, even at low MOI (O.1). APRT activity was detectable from approximately 20 h postinfection. At a low frequency, LAT cells were transformed to aprt+, and four stable transductants were selected in adenine, azaserine (AA) medium. Such cells expressed APRT at approximately 50% wild-type activity and the enzyme was shown to be CHO APRT by starch gel electrophoresis. DNA was isolated from the transductants and probed with CHO aprt-specific DNA and with viral DNA probes. The results indicated that the CHO aprt gene was integrated into the LAT cells at a site other than mouse aprt. Although neighboring viral sequences were integrated and maintained in the transductants, viral sequences further upstream and downstream of the aprt gene were absent.

Adenine↗
PubMed1991

Polymerase chain reaction amplification and sequence analysis of human mutant adenine phosphoribosyltransferase genes: the nature and frequency of errors caused by Taq DNA polymerase.

Using the polymerase chain reaction (PCR) with Taq DNA polymerase, we have amplified a 2.4-kb fragment of genomic DNA containing the adenine phosphoribosyltransferase (APRT) gene from patients with APRT deficiency. Several clones from each patient were sequenced after subcloning the PCR product into M13mp18. Selected regions of the amplified fragment were also sequenced directly. This enabled us to distinguish PCR-induced errors from endogenous mutations and polymorphisms in each clone. 44 PCR errors were found in a total of 57,94 kb of DNA sequenced from 25 clones from 7 patients. All the errors were due to the PCR process and not to subcloning, as shown by sequence analysis of 5 APRT-positive clones isolated from a phage genomic library.

Adenine Phosphoribosyltransferase↗
PubMed1991

2,8-Dihydroxyadenine lithiasis in a Japanese patient heterozygous at the adenine phosphoribosyltransferase locus.

All reported cases of 2,8-dihydroxyadenine (DHA) lithiasis have been due to functional homozygous deficiency of adenine phosphoribosyltransferase (APRT). Here we describe the first case of DHA lithiasis in a patient who has functional APRT activity in cultured lymphoblasts. The patient is heterozygous for Japanese-type (type II) APRT deficiency as demonstrated by starch-gel electrophoresis and DNA sequence analysis. We also demonstrate the use of starch-gel electrophoresis for differentiation between the type II mutant enzyme and the wild-type enzyme.

Adenine↗
PubMed1991

Identification of a single missense mutation in the adenine phosphoribosyltransferase (APRT) gene from five Icelandic patients and a British patient.

We have completely sequenced the adenine phosphoribosyltransferase (APRT) gene from each of six patients--five (I-V) from Iceland and one (VI) from Britain. Cases I and II shared a common ancestor six and seven generations ago, and cases I and V shared a common ancestor seven generations ago, but cases III and IV were unrelated to the above or to each other, over seven generations. Genomic DNA was amplified by PCR, subcloned into M13mp18, and sequenced. Genomic and PCR-amplified DNAs were also analyzed by restriction-enzyme digestion and Southern blotting. The same missense mutation was identified in all six patients. This mutation leads to the replacement of asp (GAC) by val (GTC), at amino acid position 65. The gene sequences from all patients were otherwise identical to our wild-type sequence. The homozygous nature of the mutation was confirmed by sequencing the PCR product directly. All six patients were homozygous for the 1.25-kb TaqI RFLP. The Icelandic patients were also homozygous for the 8-kb SphI RFLP, but the British patient was heterozygous at this site. These studies suggest that a founder effect is likely to be responsible for APRT deficiency in the Icelandic population. The finding of the same mutation in a patient from Britain suggests that this mutation may have originated in mainland Europe.

Adenine Phosphoribosyltransferase↗
PubMed1990

Identification of a splice mutation at the adenine phosphoribosyltransferase locus in a German family.

We examined the molecular basis of adenine phosphoribosyltransferase (APRT) deficiency in homozygous-deficient, identical twin brothers who were born to non-consanguineous German parents. DNA was isolated from blood, and the APRT gene was amplified by PCR, subcloned into M13, and sequenced completely. A single T insertion between bases 1831-1832 or 1832-1833 was identified. This alters the consensus sequence at the exon 4 - intron 4 spice donor site and leads to aberrant splicing. The same mutation has been described previously in two affected brothers from Belgium, and the Indianapolis group has also identified it in two other, unrelated Caucasian patients. Thus, this mutation may be a common cause of APRT deficiency in the Caucasian population.

Adenine Phosphoribosyltransferase↗
PubMed1987

Mutants of Saccharomyces cerevisiae deficient in adenine phosphoribosyltransferase.

Spontaneous and ethyl methanesulfate induced mutants of Saccharomyces cerevisiae, with partial and complete deficiency of adenine phosphoribosyltransferase (APRT, EC 2.4.2.7), were isolated by selection for resistance to 8-azaadenine. Matings between totally deficient mutants and tester strain resulted in diploid heterozygotes that were sensitive to azaadenine. Upon sporulation and tetrad analysis, azaadenine resistance (and APRT deficiency) segregated as expected for a single Mendelian gene. Hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) activity in the mutants was similar to that in the wild-type cells. There was no detectable activity of adenine aminohydrolase (EC 3.5.4.2) in the wild-type or mutant cells.

Adenine↗