PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Splicing mutations”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1997

Band 3 Campinas: a novel splicing mutation in the band 3 gene (AE1) associated with hereditary spherocytosis, hyperactivity of Na+/Li+ countertransport and an abnormal renal bicarbonate handling.

We have studied the molecular defect underlying band 3 deficiency in one family with hereditary spherocytosis using nonradioactive single strand conformation polymorphism of polymerase chain reaction (PCR) amplified genomic DNA of the AE1 gene. By direct sequencing, a single base substitution in the splicing donor site of intron 8 (position + 1G --> T) was identified. The study of the cDNA showed a skipping of exon 8. This exon skipping event is responsible for a frameshift leading to a premature stop codon 13 amino acids downstream. The distal urinary acidification test by furosemide was performed to verify the consequences of the band 3 deficiency in alpha intercalated cortical collecting duct cells (alphaICCDC). We found an increased basal urinary bicarbonate excretion, associated with an increased basal urinary pH and an efficient distal urinary acidification. We also tested the consequences of band 3 deficiency on the Na+/H+ exchanger, by the measurement of Na+/Li+ countertransport activity in red blood cells. The Na+/Li+ countertransport activity was increased threefold to sixfold in the patients compared with the controls. It is possible that band 3 deficiency in the kidney leads to a decrease in the reabsorption of HCO3- in alphaICCDC and anion loss, which might be associated with an increased sodium-lithium countertransport activity.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1994

A splicing mutation in the cytochrome b5 gene from a patient with congenital methemoglobinemia and pseudohermaphrodism.

We have analyzed reticulocyte and leukocyte mRNAs isolated from a patient with congenital methemoglobinemia and pseudohermaphrodism. The cytochrome b5 cDNA sequences were amplified using specific oligonucleotide primers and the polymerase chain reaction (PCR). DNA sequencing indicated that there was a 16-bp deletion in the cDNA leading to a new, in-frame stop signal and resulting in a truncated protein of 45 amino acids. Genomic DNA was analyzed, and the molecular lesion was shown to be an AG-->GG alteration in the 3' splicing junction of intron 1. The splice site alteration leads to the usage of the nearest AG as an alternative splice site, resulting in a 16-bp deletion in the mRNA. All of the studies on reticulocyte mRNA and genomic DNA indicated that the patient was homozygous for the lesion.

Base Sequence↗
PubMed1994

A novel splicing mutation in the ferrochelatase gene responsible for erythropoietic protoporphyria.

An aberrant ferrochelatase mRNA lacking exon 7 was found in a patient with erythropoietic protoporphyria (EPP). The exon 7 skipping appears to result from a G >> A transition at position +5 of the donor site of intron 7 of the ferrochelatase gene. The patient is heterozygous for the mutation. Since the patient's paternal half-brother (not available for testing) also has clinically obvious EPP, their father appeared to be the source of the mutant allele. The father was in fact found to be a carrier of the same mutation and his ferrochelatase activity was 35% of normal; however, he is asymptomatic, with only a slightly elevated erythrocyte protoporphyrin level. These findings confirm that the observed mutation is responsible for the defect. The variability in clinical expression of EPP probably reflects the great heterogeneity of the ferrochelatase gene defects and the contribution of additional exogenous and endogenous inducers of latent disease.

Alleles↗
PubMed1998

The activating splice mutation in intron 3 of the thrombopoietin gene is not found in patients with non-familial essential thrombocythaemia.

Essential thrombocythaemia (ET) is a condition of unknown aetiology characterized by sustained thrombocytosis in the absence of a detectable systemic cause. Although usually considered a clonal disease affecting myeloid cells, recent data indicate that a significant proportion of patients have polyclonal haemopoiesis. In some patients the thrombopoietin (TPO) levels are normal or raised. Recently a mutation has been described in the TPO gene in familial thrombocythaemia that results in elevated TPO levels. We have therefore screened 51 patients diagnosed with non-familial ET for the presence of this mutation, but it was not detected in any patient. The constitutional presence of this mutation is therefore unlikely to contribute to the pathogenesis of ET.

Adolescent↗
PubMed1997

Compound heterozygosity for a nonsense mutation and a splice site mutation in the type VII collagen gene (COL7A1) in recessive dystrophic epidermolysis bullosa.

Mutations in the type VII collagen gene (COL7A1) have recently been established as the molecular basis of the inherited blistering skin disorder, dystrophic epidermolysis bullosa. We report a novel combination of COL7A1 mutations in a Japanese patient with an autosomal recessive form of dystrophic epidermolysis bullosa. Clinically, the patient had suffered from generalized trauma-induced blistering since the first week of life loss of most finger- and toenails, esophageal stenosis and partial fusion of the fingers and toes. Immunofluorescence microscopy of the dermal-epidermal junction in the patient's skin revealed reduced intensity of staining with an anti-type VII collagen antibody. Transmission electron microscopy showed only a few thin, poorly formed anchoring fibrils. The patient was a compound heterozygote for a nonsense mutation on one COL7A1 allele and a donor splice site mutation on the other allele. The mutations were identified by PCR amplification of genomic DNA, heteroduplex analysis, and nucleotide sequencing, and verified by restriction endonuclease digestion. Reverse transcriptase-PCR and sequencing of cDNA from the patient's cultured keratinocyte mRNA showed evidence of aberrant splicing resulting from the donor splice site mutation, due to activation of a cryptic intronic splice site that leads to a frameshift and a downstream premature termination codon. Knowledge of the genetic lesions in this patient is helpful in elucidating the molecular consequences of COL7A1 mutations in dystrophic epidermolysis bullosa and in providing information about the fundamental mechanisms involved in maintaining adhesion between the epidermis and the dermis.

Adult↗
PubMed2003

Clinical heterogeneity and molecular findings in five Polish patients with glycerol kinase deficiency: investigation of two splice site mutations with computerized splice junction analysis and Xp21 gene-specific mRNA analysis.

Five cases of glycerol kinase deficiency are presented with clinical, biochemical, and genetic results. Two had the glycerol kinase deficiency as part of an Xp21 contiguous gene deletion syndrome-complex form-and three had an isolated form of the enzyme deficiency. In these we found two splice site mutations (IVS1+4A>G, IVS9-1G>T) and one insertion (1393_1394insG). In patients with the complex form, a deletion of the DAX1, GK genes and the distal part of the DMD gene was found. A computerized study was performed to predict the effects of the splice site mutations. It showed that the IVS9-1G>T mutation substantially altered and removed the wild-type site and enhanced a cryptic site seven nucleotides downstream, and that the IVS1+4A>G diminished the strength of the wild-type donor site from strong to leaky. To verify these predictions, we developed an RT-PCR system with gene-specific primers that exclusively amplifies the Xp21 glycerol kinase gene transcript. Identification of individuals at risk is motivated by a need to avoid delay in a correct diagnosis. For reliable identification of heterozygotes for isolated glycerol kinase deficiency, knowledge of the specific mutation in the proband is required. This is easily obtained with the RT-PCR analyses developed in this study.

Adrenal Insufficiency↗
PubMed1998

A mutation screen of the TSC1 gene reveals 26 protein truncating mutations and 1 splice site mutation in a panel of 79 tuberous sclerosis patients.

The entire coding region of the TSC1 gene has been screened for mutations in 79 unrelated patients with tuberous sclerosis. Causative mutations have been found in 27 of these patients and five other variations in the gene have been identified. 26 of the mutations are predicted to cause premature truncation of the protein product of the gene and one mutation is in a splice site. The mutation screen has revealed that TSC1 mutations are rarer in sporadic tuberous sclerosis patients than in familial cases. We have also found that the only previously described case of non-penetrance can no longer be described as such, and that a single ungual fibroma is not necessarily diagnostic of tuberous sclerosis, important findings for the genetic counselling of tuberous sclerosis patients.

Blotting, Southern↗
PubMed2000

Compound heterozygous patient with glycogen storage disease type III: identification of two novel AGL mutations, a donor splice site mutation of Chinese origin and a 1-bp deletion of Japanese origin.

Glycogen storage disease type III (GSD III) is an autosomal recessive disorder caused by deficiency of glycogen-debranching enzyme (AGL). We studied a 2-year-old GSD III patient whose parents were from different ethnic groups. Nucleotide sequence analysis of the patient showed two novel mutations: a single cytosine deletion at nucleotide 2399 (2399delC) in exon 16, and a G-to-A transition at the +5 position at the donor splice site of intron 33 (IVS33+5G>A). Analysis of the mRNA produced by IVS33+5G>A showed aberrant splicing: skipping of exon 33 and activation of a cryptic splice site in exon 34. Mutational analysis of the family revealed that the 2399delC was inherited from her father, who is of Japanese origin, and the IVS33+5G>A from her mother, who is of Chinese descent, establishing that the patient was a compound heterozygote. To our knowledge, this is the first report of a mutation identified in a GSD III patient from the Chinese population.

Child, Preschool↗
PubMed2002

Identification of seven novel missense mutations, two splice-site mutations, two microdeletions and a polymorphic amino acid substitution in the gene for ornithine transcarbamylase (OTC) in patients with OTC deficiency.

Ornithine transcarbamylase (OTC) deficiency, a X-linked disorder, is the most frequent inborn error of the urea cycle. Point mutations and small deletions/insertions in the OTC gene are responsible for the majority of the cases and have a "private" character with little recurrence. We report on eleven pathological changes in the OTC gene sequence detected in three males with mild clinical presentations, and in eight symptomatic females. All of these mutations are novel. Only one mutation affects a CpG mutational hot spot, whereas all but one of the mutations caused an abnormal SSCP of the corresponding PCR-amplified exon. Two mutations occurring in females involved one or two base deletions in codons 196 and 330, respectively, causing frameshift changes and premature termination. Another two mutations in a female and a male affected acceptor splice sites at bases -1 and -3 of the intron 6/exon 7 and intron 9/exon 10 junctions, respectively. All other mutations were point changes causing the simple amino acid substitutions (M1I, I160S, L191F, M206I, L301F, P305H and L341P), although the mutation M1I may abolish translation of the OTC polypeptide. This mutation coexisted in a female patient with the change T333A that appears to be a previously unreported polymorphism. The three male patients but only four of the eight female patients inherited the mutation.

Adult↗