Gene Microsatellite Research Articles

Lack of IFN-gamma 2/2 homozygous genotype independently of recipient age and intensity of conditioning regimen influences the risk of aGVHD manifestation after HLA-matched sibling haematopoietic stem cell transplantation.

A total of 110 patients (71 adults and 39 children) who received allogeneic haematopoietic stem cell transplantation from HLA-matched sibling donors were studied for the incidence of acute graft-versus-host disease (aGvHD) in relation to IFN-gamma gene microsatellite polymorphism. A strong tendency was observed towards the lower incidence of grades II-IV aGvHD in patients having an IFN-gamma 2/2 genotype as compared to the recipients with other IFN-gamma genotypes (0.12 vs 0.33, P=0.06). This relationship was independent of the intensity of conditioning regimen and diagnosis. IFN-gamma polymorphic features, together with other clinical and biological factors (patient's age, donor-recipient gender, diagnosis, conditioning regimen, transplant material and GvHD prophylaxis), were subjected to multivariate analysis for aGvHD manifestation in order to exclude indirect association of the IFN-gamma 2/2 genotype. In multivariate analysis, myeloablative therapy (OR=11.462, P=0.013), recipient age (OR=4.896, P=0.009) and lack of IFN-gamma 2/2 genotype (OR=4.311, P=0.048) were found to significantly contribute to the development of grade II-IV aGvHD, while type of GvHD prophylaxis showed less-strong influence (OR=2.963, P=0.066). Thus, it appeared that the IFN-gamma 2/2 genotype constituted an independent and protective factor associated with a decreased risk of grade II-IV aGvHD. However, this genotype was not found to be associated with the risk of cGvHD or survival.

The ??1Na,K-AtPase Locus Plays an Additive Role in Na,K Pump Rate Modulation with Respect to the ??-Adducin Gene in Essential Hypertension

Background: The W allele of the G460W α-adducin polymorphism is associated with increased erythrocyte Na transport rates, lower plasma renin activity (PRA) and a greater response to hydrochlorothiazide in North Sardinian patients with essential hypertension. The α1Na,K-ATPase gene microsatellite marker (D1S453ATP1A1) is associated with essential hypertension in the same ethnic group. Objective: We examined whether the D1S453ATP1A1 marker, alone and in combination with G460Wadd, is associated with erythrocyte Na transport, PRA and response to hydrochlorothiazide. Methods: D1S453ATP1A1 (6 alleles) was genotyped in 250 never-treated patients with essential hypertension in whom the G460Wadd, the erythrocyte Na transporters, PRA and blood pressure (BP) changes after 8 weeks’ hydrochlorothiazide 25 mg/day had been previously studied. Results: In patients with at least one #4D1S453 allele, compared with patients with no #4D1S453 alleles, the Na,K pump rate was faster (p < 0.001). In patients with the W460add genetic background, the D1S453ATP1A1 #4 allele is associated with a further rise in the Na,K pump rate, compared with the other D1S453ATP1A1 alleles (p < 0.001). No such effect was shown on the other Na transport systems, nor on the PRA and BP response to diuretic treatment. Conclusions: The D1S453ATP1A1 may affect the Na,K-pump function both alone and when combined with G460Wadd in essential hypertension. The G460Wadd/D1S453ATP1A1 interaction could help in understanding the pathophysiology of hypertension, and represents a further example of the concept that a given gene polymorphism could act selectively on a pertinent intermediate phenotype.

Non-radioactive detection of five common microsatellite markers for ATP7B gene in Wilson disease patients

Haplotype analysis using microsatellite markers is a useful indicator of specific mutations and is often exploited as the first large-scale screening technique to carry out the molecular characterization of the disease gene in probands from a specific population. However, the methodologies available are still cumbersome and require the use of either radioactive compounds or specialized equipment suitable to follow fluorescent dyes. Both these techniques may not be available for newly developing clinical laboratories. We have set up a sensitive and easy-to-use protocol to characterize five closely spaced, highly polymorphic microsatellite polymorphisms (CA repeats) that span the Wilson disease (WD) region, i.e. D13S316, D13S133, D13S301, D13S314, D13S315. The technique described here for the analysis of the WD gene microsatellite system relies on the quick detection method of silver staining, avoiding the use of toxic or sophisticated equipment. This approach could be the method of choice to implement molecular genetic testing in clinical laboratories, even those not especially equipped for DNA analysis and in particular in newly developed molecular genetics centers in countries whose population has not yet been characterized for WD-causing ATP7B gene mutations.

Protocolo da extração de DNA de material parafinado para análise de microssatélites em leiomioma

É apresentada a padronização de protocolo de extração de DNA de material parafinado para análise da instabilidade de microssatélites de genes relacionados ao leiomioma uterino, utilizando-se 30mg a 40mg de tecido retirado de blocos de parafina. Os blocos são desparafinizados por banhos de xilol a 65ºC, reidratados com soluções de concentrações decrescentes de ETOH e água deionizada. A extração de DNA é obtida através das etapas de lise celular, com solução Promega, digestão de proteínas por proteinase K, precipitação com proteínas com solução Promega e precipitação do DNA com ETOH 70% gelado e ressuspendido com solução Promega. Este protocolo resulta em um DNA viável para uso na reação em cadeia da polimerase (PCR).

The Adenomatous Polyposis Coli (APC) gene microsatellite marker D5S1385 is equally informative for loss of heterozygosity as the marker D5S346

Molecular analyses for loss of heterozygosity (LOH) at a gene locus are used to identify genomic imbalance in tumor tissue. A frequently utilized microsatellite marker for the Adenomatous Polyposis Coli (APC) gene is denoted D5S346. However, when an individual has two identical forms of this microsatellite, then a second microsatellite, also near the APC gene, is needed. We present data on an APC microsatellite marker designated D5S1385, located on the 5′ end of the APC gene, and we compare these to data utilizing the marker D5S346. Polymerase chain reaction (PCR) was used, followed by gel electrophoresis. Homozygosity for the marker D5S1385 was present in 55 individuals, or 28%. Thirty-seven carcinomas and 32 adenomas were assessed for LOH from individuals informative with both microsatellite markers. D5S1385 detected LOH in 39 of 41 lesions, or 95%, for which D5S346 detected LOH. D5S1385 is moderately polymorphic and is informative at least as often as D5S346.

Overlapping translation of nucleic acid sequences for bioinformatics applications

Summary: An alternative method to TblastX has been developed. Nucleic acids in database and query sequences were translated into overlapping protein-like sequences (overlappingly translated sequences or OTSs) before searching with BlastP. Thus, each nucleic acid sequences is represented by a single ‘protein like’ sequence instead of three ‘proteins’ in different reading frames. The 3×3 comparison of TblastX is represented by a single comparison, giving faster results. Additional advantages are: (1) it can be more sensitive to detect weak sequence similarities than either blastN or TblastX; (2) codon redundancy is eliminated; (3) the sensitivity to single nucleotide polymorphism, mutation and sequencing errors is reduced; (4) it is insensitive to frame shifts. Results: BlastP using OTS detected about two thirds of blastN and TblastX matches but discovered additional similarities. When blastN and TblastX against nucleic acids were compared to blastP against OTS, identical matches discovered by blastP were generally longer (602, respectively. 213 letters, p<0.01), had higher scores (748 respectively 460 bits, p<0.05) and lower E values (3.16E − 20 vs. 1.17E + 03, p<0.01) but the percentage identity was lower (25% respectively 61%, p<0.001). A qualitative evaluation with LALIGN showed an improvement of the visualization when OTS-s were used instead of nucleic acids. Many extensive sequence similarities became better visible, for example the repeating similarity between prion protein and human insulin gene micro-satellite, and the surprising similarity between the first part of prion protein coding region and the human pro-insulin (34.4% identity and additional 17.2% similarity through 238 residues, score >295 which is expected 4.6e − 18 times by chance).

P3458 Inflammatory response to coronary artery bypass surgery: does the Heme-Oxygenase-1 gene microsatellite polymorphism play a role?

P3458 Inflammatory response to coronary artery bypass surgery: does the Heme-Oxygenase-1 gene microsatellite polymorphism play a role?

Androgen receptor (AR) gene microsatellite polymorphism in postmenopausal women: correlation to bone mineral density and susceptibility to osteoporosis

Objective: To investigate the correlation of the androgen receptor gene microsatellite polymorphism (CAG trinucleotide repeat polymorphism on exon 1) with bone mineral density and their relationship to osteoporosis in postmenopausal women. Study design: A number of 168 of 477 postmenopausal women were randomly recruited. The androgen receptor gene microsatellite polymorphism was determined using polymerase chain reaction-based microsatellite analysis. Bone mineral density of the lumbar spine and proximal femur was measured using dual-energy X-ray absorptiometry. Results: The AR genotype was classified from “9” to “32” according to the number of CAG trinucleotide repeats they contained to represent “signposts”. After adjustment for potential confounding factors such as age, height, weight, years since menopause, and daily calcium intake, subjects with genotype 20+ ( n=64) had lower bone mineral density values and a significantly greater risk for osteoporosis (OR 4.2, 95% CI 1.0–17.2) when compared with subjects with genotype 20− ( n=104) at the femoral neck. Conclusion: The present study suggests that the androgen receptor gene microsatellite polymorphism may be a candidate genetic marker for risk of osteoporosis in postmenopausal women.

Microsatellites in starch-synthesizing genes in relation to starch physicochemical properties in waxy rice ( Oryza sativa L.).

Rice starch is composed of amylose and amylopectin. Amylose content, an important determinant of rice starch quality, is primarily controlled by the waxy gene, encoding granule-bound starch synthase (GBSS). The starch branching enzyme (SBE) and soluble starch synthase (SSS) play major roles in the synthesis of amylopectin. Microsatellite polymorphisms in the three genes, the wx gene encoding granule-bound starch synthase I, the SBE gene encoding starch branching enzyme I and the SSS gene encoding soluble starch synthase I, were studied for 56 accessions of waxy rice ( Oryza sativa L.). Four (CT)(n) microsatellite alleles, (CT)(16), (CT)(17), (CT)(18) and (CT)(19), at the wx locus were detected in this set of waxy rice, of which (CT)(17) was the most frequent. Three (CT)(n) microsatellite allele classes were found at the SBE locus, (CT)(8) or (CT)(10) together with an insertion sequence of CTCTCGGGCGA, and (CT)(8) alone without the insertion. There were multiple microsatellites clustered at the SSS locus. However, these alleles can also be grouped into three classes, i.e. the allele class SSS-A = (AC)(2) em leader TCC(TC)(11) em leader (TC)(5)C(ACC)(11), the allele class SSS-B = (AC)(3) em leader TCT(TC)(6) em leader (TC)(4)C(ACC)(9), and the allele class SSS-C = (AC)(3) em leader TCT(TC)(6) em leader (TC)(4)C(ACC)(8). The analyses of starch physicochemical properties among different microsatellite genotypes indicated that the waxy rice group with the (CT)(19) allele, the SBE-A allele and the SSS-B allele was quite different from other groups. Nine out of 15 accessions with a high gelatinization temperature (GT) belonged to the wx (CT)(19) group, all of them belonged to the SBE-A group and 13 of them belonged to the SSS-B group. These microsatellites might be useful in marker-assisted breeding for the improvement of rice grain quality.

Inflammatory bowel disease in children and adolescents: Working Group Report of the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition.

Inflammatory bowel disease in children and adolescents: Working Group Report of the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition.

Relation of the estrogen receptor α gene microsatellite polymorphism to bone mineral density and the susceptibility to osteoporosis in postmenopausal Chinese women in Taiwan

Objective: Osteoporosis is a common disorder with a strong genetic component. Our aim was to investigate the correlation of the estrogen receptor α gene microsatellite polymorphism (TA dinucleotide repeat polymorphism 5′ upstream of exon 1) with bone mineral density and their relationship to osteoporosis. Methods: We determined the estrogen receptor α gene microsatellite polymorphism using polymerase chain reaction-based microsatellite analysis in postmenopausal Chinese women in Taiwan. Bone mineral density of the lumbar spine and proximal femur were measured using dual-energy X-ray absorptiometry. Results: The ERα genotype was classified into ‘12’ through ‘27’ according to the number of TA dinucleotide repeats they contained, as a ‘signpost’. After adjustment for potential confounding factors including age, height, and weight, subjects with genotype 18+ ( n=4) had lower bone mineral density values and a 54.5 times greater risk for osteoporosis when compared with subjects with genotype 18− ( n=170) at the lumbar spine. This should be interpreted with caution because of the small number of subjects with the unfavorable genotype 18+. According to mean number of TA dinucleotide repeats, women with a high number of repeats (TA≧20) ( n=38) had the lowest bone mineral density and a 6.1 times greater risk for osteoporosis than women with a low number of repeats (TA≦15) ( n=61) at the femoral neck, after adjustment for potential confounding factors such as age, height, and weight. Conclusion: The present study suggests that the estrogen receptor α gene microsatellite polymorphism may be a candidate genetic marker for risk of osteoporosis in postmenopausal Chinese women in Taiwan.

Microsatellites in the eukaryotic DNA mismatch repair genes as modulators of evolutionary mutation rate.

All minor components of the human DNA mismatch repair (MMR) system-MSH3, MSH6, PMS2, and the recently discovered MLH3-contain mononucleotide microsatellites in their coding sequences. This intriguing finding contrasts with the situation found in the major components of the DNA MMR system-MSH2 and MLH1-and, in fact, most human genes. Although eukaryotic genomes are rich in microsatellites, non-triplet microsatellites are rare in coding regions. The recurring presence of exonal mononucleotide repeat sequences within a single family of human genes would therefore be considered exceptional.

Genotoxicity of the steroidal oestrogens oestrone and oestradiol: possible mechanism of uterine and mammary cancer development

Oestrogens, including the natural hormones oestrone and oestradiol, induce various tumours in laboratory animals and have been recognized to be carcinogens in humans, raising the risk for breast and uterine cancer. As part of the search for the mechanism of hormone‐induced carcinogenesis, various types of DNA damage have been detected which have been induced by oestrogens in cell‐free systems, in cells in culture, or in vivo. Nevertheless, oestrogens have been postulated to act only as promoters of mammary carcinogenesis by receptor‐mediated growth stimulation without consideration of their genotoxicity because these hormones failed to induce mutations in commonly used assays. More recently, oestradiol‐induced numerical chromosomal changes (aneuploidy) and structural chromosomal aberrations have been detected in cells in culture and in hamster kidney, a target of oestrogen‐induced cancer. In this animal model, oestradiol generates c‐myc gene amplification and microsatellite instability. Mutations of the hprt gene have been induced by oestradiol in V79 cells and by catecholoestrogen metabolites in Syrian hamster embryo cells. Sequencing of this gene isolated from V79 mutant clones revealed point mutations and deletions. It is concluded that oestradiol plays a dual role as mutagen/carcinogen and as growth‐stimulating hormone in the induction of tumours.

Lack of association between estrogen receptor beta dinucleotide repeat polymorphism and autoimmune thyroid diseases in Japanese patients.

BackgroundThe autoimmune thyroid diseases (AITDs), such as Graves' disease (GD) and Hashimoto's thyroiditis (HT), appear to develop as a result of complex interactions between predisposing genes and environmental triggers. Susceptibility to AITDs is conferred by genes in the human leukocyte antigen (HLA) and genes unlinked to HLA, including the CTLA-4 gene. Recently, estrogen receptor (ER) β, located at human chromosome 14q23-24.1, was identifed. We analyzed a dinucleotide (CA)n repeat polymorphism located in the flanking region of ERβ gene in patients with AITDs and in normal subjects. High heterozygosity makes this polymorphism a useful marker in the genetic study of disorders affecting female endocrine systems. We also correlated a ERβ gene microsatellite polymorphism with bone mineral density (BMD) in the distal radius and biochemical markers of bone turnover in patients with GD in remission.ResultsFourteen different alleles were found in 133 patients with GD, 114 patients with HT, and 179 controls subjects. The various alleles were designated as allele*1 through allele*14 according to the number of the repeats, from 18 to 30. There was no significant difference in the distributions of ERβ alleles between patient groups and controls. Although recent study demonstrated a significant relation between a allele*9 in the ERβ gene and BMD in postmenopausal Japanese women, there were no statistically significant interaction between this allele and BMD in the distal radius, nor biochemical markers in patients with GD in remission.ConclusionsThe present results do not support an association between the ERβ microsatellite marker and AITD in the Japanese population. We also suggest that the ERβ microsatellite polymorphism has at most a minor pathogenic importance in predicting the risk of osteoporosis as a complication of GD.

Gene amplification and microsatellite instability induced in tumorigenic human bronchial epithelial cells by alpha particles and heavy ions.

Gene amplification and microsatellite alteration are useful markers of genomic instability in tumor and transformed cell lines. It has been suggested that genomic instability contributes to the progression of tumorigenesis by accumulating genetic changes. In this study, amplification of the carbamyl-P-synthetase, aspartate transcarbamylase, dihydro-orotase (CAD) gene in transformed and tumorigenic human bronchial epithelial (BEP2D) cells induced by either alpha particles or (56)Fe ions was assessed by measuring resistance to N-(phosphonacetyl)-l-aspartate (PALA). In addition, alterations of microsatellite loci located on chromosomes 3p and 18q were analyzed in a series of primary and secondary tumor cell lines generated in nude mice. The frequency of PALA-resistant colonies was 1-3 x 10(-3) in tumor cell lines, 5-8 x 10(-5) in transformed cells prior to inoculation into nude mice, and less than 10(-7) in control BEP2D cells. Microsatellite alterations were detected in all 11 tumor cell lines examined at the following loci: D18S34, D18S363, D18S877, D3S1038 and D3S1607. No significant difference in either PALA resistance or microsatellite instability was found in tumor cell lines that were induced by alpha particles compared to those induced by (56)Fe ions.

Study on molecular mechanism of liver yang ascending syndrome in hypertension

Objective: To investigate the molecular mechanism of Liver Yang Ascending Syndrome (LYAS) in hypertension.Methods: The plasma norepinephrine (NE), epinephrine (E) contents in patients with LYAS or Liver and Kidney Yin Deficiency Syndrome ( LKYDS) of hypertension and normal controls were determined by high performance liquid chromatography-electrochemical detector (HPLC-ECD). The polymorphism of tyrosine hydroxylase (TH) gene in the three groups were analysed by Southern Blot assay. The polymorphism of TH and monoamine oxidation A(MAO-A), monoamine oxidation B(MAO-B) gene microsatellite in these groups were analysed by polymerase chain reaction (PCR)-SSCP. At the same time, the LYAS model was established by administering Aconitum preparation (AP) to spontaneous hypertension rats (SHR). The adrenal gland medulla of the experimental animal was examined for their TH expression at the protein level after ABC immuno-histochemical staining with the TH monoclonal antibody (McAb). The adrenal TH gene mRNA expression was demonstrated by in situ hybridization with the synthetized TH oligonucleic acid probe. The results of immuno-histochemistry and in situ hybridization were analyzed with the image analysis system ( IAS).Results: The plasma NE and E contents in patients with LYAS were more obviously increased than those in LKYDS and normal controls. The TH gene amplified and the type A1 TH microsatellite D11S4046 was markedly higher in the LYAS group than those in the other groups. The TH mRNA protein expression in the adrenal tissue of the AP induced LYAS model in SHR elevated.Conclusion: The LYAS of hypertension has the characters as amplified TH gene and increased TH mRNA and protein expression, which suggested that the overex-pression of TH is probably the mechanism of LYAS in hypertension.

The generation of diversity by Haemophilus influenzae

This short article has described how microsatellites can be markers for highly adaptable genes responsible for both intra- and interstrain diversity in H. influenzae. Such genes are often associated with allelic polymorphisms and have a heterogeneous distribution. Variation in the length of repetitive sequences is a key factor in the rapid rate of change in gene expression associated with these loci. The contribution of characteristics of microsatellites other than the length of the repetitive tract to the rate of on–off switching has yet to be explored in detail and several questions remain. Why is the same nucleotide sequence often found in different microsatellites in genes of related function? What is the effect on the mutation rate of the different nucleotides and number of nucleotides forming each repeat unit? Finally, the possibility that trans-acting elements affect the rate of slipped-strand mispairing and the repair of these mutations has been raised and merits further investigation14xHypermutation in pathogenic bacteria: frequent phase variation in meningococci is a phenotypic trait of a specialized mutator biotype. Bucci, C. Mol. Cell. 1999; 3: 435–445Abstract | Full Text | Full Text PDF | PubMed | Scopus (94)See all References14. An understanding of the multiple factors affecting these hypermutable loci will facilitate future studies to determine how and when this plethora of phenotypes promotes survival.

Tyrosine hydroxylase gene microsatellite polymorphism associated with insulin resistance in depressive disorder

A high association between type 2 diabetes mellitus and depressive illness has been reported. Insulin resistance during depressive illness might contribute to the linkage between depression and type 2 diabetes. To determine whether the genetic polymorphisms of the tyrosine hydroxylase ([TH] HUMTH01) and insulin (INS-VNTR) genes contribute to insulin resistance in depressive illness, we analyzed the association between the polymorphisms and insulin resistance in 41 Japanese patients with depressive disorder, 204 normal control subjects, 161 cohort subjects with normal glucose tolerance (NGT) and without depressive symptomatology, and 59 NGT subjects with depressive symptomatology. The depressive patients had a significantly lower insulin sensitivity index (SI) than the control subjects (P = .016). Depressive NGT subjects had a significantly higher homeostasis model assessment (HOMA) insulin resistance index [HOMA(R)] than the nondepressive NGT subjects (P < .0001). The depressive patients and NGT subjects had more HUMTH01 allele 7 (TH7) than the controls and nondepressive NGT subjects. SI was significantly lower in patients with the TH7/7 homozygote versus patients with the other genotypes and the controls. TH7 was associated with higher HOMA(R) as compared with the other alleles in the NGT subjects. Insulin resistance was associated with depressive disorders. The HUMTH01 and INS-VNTR were associated with insulin resistance and depressive symptoms.

Study of V1-vascular Vasopressin Receptor Gene Microsatellite Polymorphisms in Human Essential Hypertension

M. Thibonnier, M. K. Graves, M. S. Wagner, N. Chatelain, F. Soubrier, P. Corvol, H. F. Willard and X. Jeunemaitre. Study of V1-vascular Vasopressin Receptor Gene Microsatellite Polymorphisms in Human Essential Hypertension. Journal of Molecular and Cellular Cardiology (2000) 32, 557–564. Vasopressin (AVP) actions on vascular tone and blood pressure are mainly mediated by the V1-vascular receptor (V1R). We recently reported the structure and functional expression of the human V1R cDNA and described the genomic characteristics, tissue expression, chromosomal localization, and regional mapping of the human V1R gene, AVPR1A. To test whether the V1R is a marker for human essential hypertension, we sequenced the human AVPR1A gene and its 5 upstream region and found several DNA microsatellite motifs. One (GT)14-(GA)13-(A)8microsatellite is located 2983 bp downstream of the transcription start site, within a 2.2 kbp intron interrupting the coding sequence of the receptor. Three other microsatellites are present in the 5 flanking DNA of the AVPR1A gene: a (GT)25dinucleotide repeat, a complex (CT)4-TT-(CT)8-(GT)24motif and a (GATA)14tetranucleotide repeat located respectively 3956 bp, 3625 bp and 553 bp upstream of the transcription start site. Analysis of these polymorphisms in 79 hypertensive and 86 normotensive subjects for the (GT)14-(GA)13-(A)8and the (GT)25motifs revealed a high percentage of heterozygosity but no difference in alleles frequencies between the two groups. A linkage study using the affected sib pair method and the (GT)25repeat in 446 hypertensive sib pairs from 282 French Caucasian pedigrees showed no excess of alleles sharing at the AVPR1A locus. No linkage was found in the subgroups of patients with early onset hypertension (diagnosis before age 40) or severe hypertension (diastolic blood pressure ≥100 mmHg or requirement for ≥two medications). These findings suggest that molecular variants of the V1R gene are not involved in unselected forms of essential hypertension.

The FHIT gene in oral squamous cell carcinoma: allelic imbalance is frequent but cDNA aberrations are uncommon

The FHIT (fragile histidine triad) gene at chromosome 3p14.2 spans the FRA3B fragile site and encodes for a diadenosine triphosphate hydrolase-type protein. FHIT is frequently abnormal in solid tumours including those of the upper aerodigestive tract (UAT) and has therefore been proposed as a tumour-suppressor gene. This proposition was evaluated here for oral squamous cell carcinoma (SCC) using microsatellite analysis, reverse transcription-polymerase chain reaction (RT-PCR), FHIT exon 5 PCR and direct sequencing. Fifty-eight primary oral SCCs were examined with two FHIT gene microsatellite markers (D3S4103 and D3S1300) and two markers flanking FHIT. Allelic imbalance (AI) occurred in 28 of 52 informative cases (54%) at one or both FHIT markers (D3S4103: 53%; D3S1300: 42%). A significant association was noted between frequency of AI and advanced stage tumours for D3S4103 but not between AI frequency and smoking. AI frequency at D3S1300 and at a flanking marker correlated with low survival. Of eight oral/UAT SCC cell lines examined, six produced abundant wild-type transcript and one yielded mostly truncated transcripts, the most abundant of which lacked exons 5-7. A double deletion was also detected in one of 11 primary oral SCCs. Our microsatellite assay results show that the FHIT gene is frequently disrupted in oral SCC. However, as FHIT was shown to be expressed normally in the great majority of oral/UAT SCCs studied, its likely involvement in the molecular pathogenesis of the disease as a tumour suppressor remains doubtful.