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Background: Lactose intolerance with adult-onset is due to the inadequate enzymatic activity of lactase-phlorizin hydrolase (LPH). It is frequently seen in patients with Crohn disease, but the mechanism remains to be elucidated. Two DNA genotypes, C/C -13910 and G/G -22018 , located upstream from the LCT locus, the gene encoding for LPH, were recently identified as representing genetic markers for lactose intolerance. We utilized these two DNA genotypes to study their role in inflammatory bowel disease. Methods: We investigated the prevalence of these two DNA variants using specific restriction enzyme digest assays in 166 patients with Crohn disease, in 120 healthy first-degree relatives of Crohn disease patients, in 63 patients with ulcerative colitis and in 187 healthy individuals. Results: The analysis revealed a frequency of 21.4% of the 2 genotypes for adult-type hypolactasia in our studied German cohort of healthy individuals, which is higher than previously reported (15%) based on the hydrogen (H 2 ) breath test. This might indicate a higher sensitivity of genotyping, but it has to be confirmed in larger cohorts. No significant difference was detectable in the frequency of the C/C -13910 and G/G -22018 genotypes in patients with Crohn disease (C/C -13910 : 21.7%; G/G -22018 : 22.3%) compared to first-degree relatives (C/C -13910 : 21.7%; G/G -22018 : 20.8%), patients with ulcerative colitis (C/C -13910 : 20.3%; G/G -22018 : 20.3%) and healthy individuals (C/C -13910 : 21.4%; G/G -22018 : 21.4%). Conclusion: The C/C -13910 and G/G -22018 genotype of adult-type hypolactasia is not associated with susceptibility to the pathogenesis of Crohn disease and ulcerative colitis. [ABSTRACT FROM AUTHOR]

Eukaryotic MutLα (mammalian MLH1-PMS2 heterodimer; MLH1-PMS1 in yeast) functions in early steps of mismatch repair as a latent endonuclease that requires a mismatch, MutSα/β, and DNA-loaded proliferating cell nuclear antigen (PCNA) for activation. We show here that human PCNA and MutLα interact specifically but weakly in solution to form a complex of approximately 1:1 stoichiometry that depends on PCNA interaction with the C-terminal endonuclease domain of the MutLα PMS2 subunit. Amino acid substitution mutations within a PMS2 C-terminal 721 QRLIAP motif attenuate or abolish human MutLα interaction with PCNA, as well as PCNA-dependent activation of MutLα endonuclease, PCNA- and DNA-dependent activation of MutLα ATPase, and MutLα function in in vitro mismatch repair. Amino acid substitution mutations within the corresponding yeast PMS1 motif ( 723 QKLIIP) reduce or abolish mismatch repair in vivo. Coupling of a weak allele within this motif ( 723 AKLIIP) with an exo1 Δ null mutation, which individually confer only weak mutator phenotypes, inactivates mismatch repair in the yeast cell., Competing Interests: The authors declare no conflict of interest.

Repair of dsDNA breaks requires processing to produce 3'-terminated ssDNA. We biochemically reconstituted DNA end resection using purified human proteins: Bloom helicase (BLM); DNA2 helicase/nuclease; Exonuclease 1 (EXO1); the complex comprising MRE11, RAD50, and NBS1 (MRN); and Replication protein A (RPA). Resection occurs via two routes. In one, BLM and DNA2 physically and specifically interact to resect DNA in a process that is ATP-dependent and requires BLM helicase and DNA2 nuclease functions. RPA is essential for both DNA unwinding by BLM and enforcing 5' → 3' resection polarity by DNA2. MRN accelerates processing by recruiting BLM to the end. In the other, EXO1 resects the DNA and is stimulated by BLM, MRN, and RPA. BLM increases the affinity of EXO1 for ends, and MRN recruits and enhances the processivity of EXO1. Our results establish two of the core machineries that initiate recombinational DNA repair in human cells.

The DNA mismatch repair protein PMS2 was recently found to encode a novel endonuclease activity. To determine the biological functions of this activity in mammals, we generated endonuclease-deficient Pms2E702K knock-in mice. Pms2EK/EK mice displayed increased genomic mutation rates and a strong cancer predisposition. In addition, class switch recombination, but not somatic hypermutation, was impaired in Pms2EK/EK B cells, indicating a specific role in Ig diversity. In contrast to Pms2-/- mice, Pms2EK/EK male mice were fertile, indicating that this activity is dispensable in spermatogenesis. Therefore, the PMS2 endonuclease activity has distinct biological functions and is essential for genome maintenance and tumor suppression.

MutSbeta (MSH2-MSH3) mediates repair of insertion-deletion heterologies but also triggers triplet repeat expansions that cause neurological diseases. Like other DNA metabolic activities, MutSbeta interacts with proliferating cell nuclear antigen (PCNA) via a conserved motif (QXX(L/I)XXFF). We demonstrate that MutSbeta-PCNA complex formation occurs with an affinity of approximately 0.1 microM and a preferred stoichiometry of 1:1. However, up to 20% of complexes are multivalent under conditions where MutSbeta is in molar excess over PCNA. Conformational studies indicate that the two proteins associate in an end-to-end fashion in solution. Surprisingly, mutation of the PCNA-binding motif of MutSbeta not only abolishes PCNA binding, but unlike MutSalpha, also dramatically attenuates MutSbeta-MutLalpha interaction, MutLalpha endonuclease activation, and bidirectional mismatch repair. As predicted by these findings, PCNA competes with MutLalpha for binding to MutSbeta, an effect that is blocked by the cell cycle regulator p21(CIP1). We propose that MutSbeta-MutLalpha interaction is mediated in part by residues ((L/I)SRFF) embedded within the MSH3 PCNA-binding motif. To our knowledge this is the first case where residues important for PCNA binding also mediate interaction with a second protein. These findings also indicate that MutSbeta- and MutSalpha-initiated repair events differ in fundamental ways.

A purified system comprised of MutSalpha, MutLalpha, exonuclease 1 (Exo1), and replication protein A (RPA) (in the absence or presence of HMGB1) supports 5'-directed mismatch-provoked excision that terminates after mismatch removal. MutLalpha is not essential for this reaction but enhances excision termination, although the basis of this effect has been uncertain. One model attributes the primary termination function in this system to RPA, with MutLalpha functioning in a secondary capacity by suppressing Exo1 hydrolysis of mismatch-free DNA (Genschel, J., and Modrich, P. (2003) Mol. Cell 12, 1077-1086). A second invokes MutLalpha as the primary effector of excision termination (Zhang, Y., Yuan, F., Presnell, S. R., Tian, K., Gao, Y., Tomkinson, A. E., Gu, L., and Li, G. M. (2005) Cell 122, 693-705). In the latter model, RPA provides a secondary termination function, but together with HMGB1, also participates in earlier steps of the reaction. To distinguish between these models, we have reanalyzed the functions of MutLalpha, RPA, and HMGB1 in 5'-directed mismatch-provoked excision using purified components as well as mammalian cell extracts. Analysis of extracts derived from A2780/AD cells, which are devoid of MutLalpha but nevertheless support 5'-directed mismatch repair, has demonstrated that 5'-directed excision terminates normally in the absence of MutLalpha. Experiments using purified components confirm a primary role for RPA in terminating excision by MutSalpha-activated Exo1 but are inconsistent with direct participation of MutLalpha in this process. While HMGB1 attenuates excision by activated Exo1, this effect is distinct from that mediated by RPA. Assay of extracts derived from HMGB1(+/+) and HMGB1(-/-) mouse embryo fibroblast cells indicates that HMGB1 is not essential for mismatch repair.

Mismatch repair contributes to genetic stability, and inactivation of the mammalian pathway leads to tumor development. Mismatch correction occurs by an excision-repair mechanism and has been shown to depend on the 5' to 3' hydrolytic activity exonuclease 1 (Exo1) in eukaryotic cells. However, genetic and biochemical studies have indicated that one or more Exo1-independent modes of mismatch repair also exist. We have analyzed repair of nicked circular heteroduplex DNA in extracts of Exo1-deficient mouse embryo fibroblast cells. Exo1-independent repair under these conditions is MutL alpha-dependent and requires functional integrity of the MutL alpha endonuclease metal-binding motif. In contrast to the Exo1-dependent reaction, we have been unable to detect a gapped excision intermediate in Exo1-deficient extracts when repair DNA synthesis is blocked. A possible explanation for this finding has been provided by analysis of a purified system comprised of MutS alpha, MutL alpha, replication factor C, proliferating cell nuclear antigen, replication protein A, and DNA polymerase delta that supports Exo1-independent repair in vitro. Repair in this system depends on MutL alpha incision of the nicked heteroduplex strand and dNTP-dependent synthesis-driven displacement of a DNA segment spanning the mismatch. Such a mechanism may account, at least in part, for the Exo1-independent repair that occurs in eukaryotic cells, and hence the modest cancer predisposition of Exo1-deficient mammalian cells.

The error-free repair of double-stranded DNA breaks by homologous recombination requires processing of broken ends. These processed ends are substrates for assembly of DNA strand exchange proteins that mediate DNA strand invasion. Here, we establish that human BLM helicase, a member of the RecQ family, stimulates the nucleolytic activity of human exonuclease 1 (hExo1), a 5'-->3' double-stranded DNA exonuclease. The stimulation is specific because other RecQ homologs fail to stimulate hExo1. Stimulation of DNA resection by hExo1 is independent of BLM helicase activity and is, instead, mediated by an interaction between the 2 proteins. Finally, we show that DNA ends resected by hExo1 and BLM are used by human Rad51, but not its yeast or bacterial counterparts, to promote homologous DNA pairing. This in vitro system recapitulates initial steps of homologous recombination and provides biochemical evidence for a role of BLM and Exo1 in the initiation of recombinational DNA repair.

Wilson's disease (WD) is a rare inborn metabolic error characterized by deficient biliary copper excretion secondary to ATP7B gene mutations. Neurological presentations are variable in respect to both pattern and age of onset; commonly a movement disorder presents in the second or third decade. The aim of this study was to ascertain genotype correlations with distinct neurological manifestations in 41 WD patients in a Brazilian center for WD. A total of 23 distinct mutations were detected, and the frameshift 3402delC had the highest allelic frequency (31.7%). An association between 3402delC and dysphagia was detected (p=0.01) but the limited number of patients is insufficient to allow one to draw conclusions. Both clinical studies analyzing larger cohorts and basic research on ATP7B protein function could potentially shed more light on our understanding of WD.

Background: Inflammatory bowel disease (IBD) results from an aberrant immune response to the indigenous intestinal flora in genetically susceptible hosts. Therefore, the study of candidate genes involved in host pathogen interactions is of key interest., Methods: In this two-center, retrospective German and Hungarian cohort study, patients with Crohn's disease (CD) (n = 379; German n = 235, Hungarian n = 144) and ulcerative colitis (UC) (n = 263; German n = 145, Hungarian n = 118) and healthy controls (n = 605; German n = 403, Hungarian n = 202) were genotyped for the presence of the CD14 c.1-260C>T promoter variant and the TLR4 c.896A>G (p.D299G) variant by melting curve analysis using fluorescence resonance energy transfer probes. Data were stratified according to the presence of NOD2 (CARD15) mutations and a detailed genotype-phenotype analysis was performed., Results: In the German cohort the CD14 single-nucleotide polymorphism was associated with UC, but not CD (UC p = 0.016 vs. CD p = 0.190), while the opposite was found in the Hungarian cohort (UC p = 0.083 vs. CD p = 0.019). No association of IBD with the TLR4 single-nucleotide polymorphism was found in either cohort (UC p = 0.430, CD p = 0.783 vs. UC p = 0.745, CD p = 0.383)., Conclusion: IBD appears to be associated with the CD14 c.1-260C>T promoter variant in Germans and Hungarians, but not with the TLR4 c.896A>G (p.D299G) variant.

Background: One-third of cases of dilated cardiomyopathy (DCM) is of familial aetiology. Several genes have been reported to cause the autosomal dominant form of DCM., Aims: To analyze the lamin A/C gene (LMNA) in 31 unrelated patients with DCM and conduction system disease (CSD)., Methods: Patients and family members underwent physical examination, ECG/Holter-ECG, echocardiography, and selective coronary angiography. Genetic analysis of all coding exons of LMNA was performed using PCR and sequencing., Results: Three different LMNA mutations (Arg377His, c.1397delA, c.424_425ins21nt) were identified in three families with autosomal dominant disease comprised of 39 individuals. 21 individuals were mutation carriers, of whom 12 were symptomatic. We observed a progressive and age-dependent form of DCM with CSD and arrhythmias. First, the patients developed a moderate left ventricular dilatation without symptoms. Later, systolic function declined progressively and the patients became symptomatic resulting in a high mortality due to sudden death and heart failure., Conclusions: Genetic screening leads to the identification of symptomatic and asymptomatic mutant carriers. The latter at a young age should be regarded as "presymptomatic" because of the age-dependent disease manifestation. New guidelines are required for the management of these individuals.

Objectives: Genetic variants within DLG5 were recently reported to be associated with inflammatory bowel disease (IBD). The aim of our study was to test for allelic and haplotype associations of six DLG5 variants in 668 IBD patients from two European populations. Furthermore, we evaluated whether DLG5 variants alter gastrointestinal permeability in Crohn's disease (CD)., Methods: Six DLG5 variants (p.R30Q, p.P1371Q, p.G1066G, rs2289308, DLG_e26, p.D1507D) were genotyped in two study populations: (1) German IBD patients (CD n = 250; ulcerative colitis (UC) n = 150) and German healthy controls (n = 422); (2) Hungarian IBD patients (CD n = 144; UC n = 124) and Hungarian healthy controls (n = 205). Subtyping analysis was performed in respect of CARD15 mutations and clinical characteristics. We also tested for differences within DLG5 genotypes in German CD patients with respect to gastroduodenal and intestinal permeability measured by triple-sugar-test., Results: Allele as well as genotype frequencies of DLG5 variants did not differ between IBD patients and controls in either study population. Indeed, the p.R30Q polymorphism was found more frequently in controls than in patients. The distribution of DLG5 genotypes in German and Hungarian CD patients with CARD15 mutations was not different from patients without mutated CARD15. We did also not observe any association between DLG5 variants and clinical parameters. Importantly, DLG5 variants were not associated with gastroduodenal or intestinal permeability., Conclusions: We could not replicate that DLG5 is a relevant disease susceptibility gene for IBD in German or Hungarian subjects. In addition, we have no evidence that DLG5 variants are involved in altered gastrointestinal permeability in CD.

Background and Aims: A genetically impaired intestinal barrier function has long been suspected to be a predisposing factor for Crohn's disease (CD). Recently, mutations of the capsase recruitment domain family, member 15 (CARD15) gene have been identified and associated with CD. We hypothesise that a CARD15 mutation may be associated with an impaired intestinal barrier., Methods: We studied 128 patients with quiescent CD, 129 first degree relatives (CD-R), 66 non-related household members (CD-NR), and 96 healthy controls. The three most common CARD15 polymorphisms (R702W, G908R, and 3020insC) were analysed and intestinal permeability was determined by the lactulose/mannitol ratio., Results: Intestinal permeability was significantly increased in CD and CD-R groups compared with CD-NR and controls. Values above the normal range were seen in 44% of CD and 26% of CD-R but only in 6% of CD-NR, and in none of the controls. A household community with CD patients, representing a common environment, was not associated with increased intestinal permeability in family members. However, 40% of CD first degree relatives carrying a CARD15 3020insC mutation and 75% (3/4) of those CD-R with combined 3020insC and R702W mutations had increased intestinal permeability compared with only 15% of wild-types, indicating a genetic influence on barrier function. R702W and G908R mutations were not associated with high permeability., Conclusions: In healthy first degree relatives, high mucosal permeability is associated with the presence of a CARD15 3020insC mutation. This indicates that genetic factors may be involved in impairment of intestinal barrier function in families with IBD.

We compared the effect of the p.H1069Q mutation and other non-p.H1069Q mutations in ATP7B on the phenotypic expression of Wilson's disease (WD), and assessed whether the clinical phenotype of WD in compound heterozygotes depends on the type of mutation coexisting with the p.H1069Q. One hundred forty-two patients with clinically, biochemically, and genetically diagnosed WD were studied. The mutational analysis of ATP7B was performed by direct sequencing. A total number of 26 mutations in ATP7B were identified. The p.His1069Gln was the most common mutation (allelic frequency: 72%). Seventy-three patients were homozygous for this mutation. Of compound heterozygotes, 37 had frameshift/nonsense mutation, and 20 had other missense mutation on one of their ATP7B alleles. Twelve patients had two non-p.H1069Q mutations. Patients homozygous for the p.H1069Q mutation had the less severe disturbances of copper metabolism and the latest presentation of first WD symptoms. The most severely disturbed copper metabolism and the earliest age at initial disease manifestation was noticed in non-p.H1069Q patients. In compound heterozygotes, the type of mutation coexisting with the p.H1069Q to a small extent influenced WD phenotype. The phenotype of WD varied considerably among patients with the same genotype. The p.H1069Q mutation is associated with late WD manifestation and with a mild disruption of copper metabolism. In compound heterozygotes, the phenotype of WD to a small extent depends on the type of mutation coexisting with the p.H1069Q. Besides genotype, additional modifying factors seem to determine WD manifestations., (Copyright (c) 2005 Movement Disorder Society.)

The reaction responsible for replication error correction by mismatch repair proceeds via several steps: mismatch recognition, mismatch-provoked excision, repair DNA synthesis, and ligation. Key steps in this process are the recognition and subsequent exonucleolytic removal of the mispair. A minimal system comprised of human MutSalpha (MSH2*MSH6), MutLalpha (MLH1*PMS2), exonuclease I (EXOI), replication protein A (RPA), proliferating cell nuclear antigen (PCNA), and replication factor C (RFC) is sufficient to support mismatch-provoked excision in vitro. This chapter describes methods for analysis of the reconstituted excision reaction.

Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism. The clinical phenotype of the disease is varied. It is proposed that this variation may be a result of differential functional disruption of ATPase7B (ATP7B) resulting from mutations in the gene ATP7B. We aimed to assess the relationship between specific mutational defects in ATP7B and divergence in the phenotypic expression of WD. One hundred and forty-two patients with clinically, biochemically and genetically diagnosed WD were included in the study. The phenotypic expression of WD was compared between patients with different types of mutations in ATP7B, detected by direct sequencing of exons 1-21 of the gene. Twenty-six mutations were identified in ATP7B; eleven of them were mutations predicted to result in the absence of a full-length normal protein [frameshift/nonsense mutations; classified as 'severe' mutations (SMs)], 14 were missense mutations (MMs) and one was a splice site mutation. Patients with one or two SMs on their alleles had lower serum copper and ceruloplasmin and were younger when the first symptoms of the disease appeared, compared with individuals with two MMs. The effect of SMs on the WD phenotype was dose-dependent. It is concluded that mutations within ATP7B are very heterogeneous. Frameshift and nonsense mutations are associated with a severe phenotype of WD.

Dunnigan-type familial partial lipodystrophy (FPLD) is caused by mutations in LMNA, the gene that encodes nuclear lamins A and C. FPLD is characterized by peripheral fat loss, excess central adiposity, insulin resistance, and hyperlipidaemia, which are difficult to treat. We present our 2 years' experience of treatment with rosiglitazone in a subject with FPLD. Insulin requirement decreased significantly from 240 IU/day to 76 IU/day (range 20-240 IU/day) and serum triglyceride concentration was lowered from 13.7 +/- 14.4 mmol/l to 4.5 +/- 4.3 mmol/l and remained stable. Mean HbA(1c) prior to rosiglitazone therapy was 9.4 +/- 1.32% and decreased to 7.4 +/- 0.6% during therapy with rosiglitazone. This case demonstrates the benefits of PPARgamma-agonists on glycaemic control and dyslipidaemia in a patient with FPLD. This in turn implies that PPARgamma may play a pathophysiological role in FPLD.

Objectives: Characterization of familial clusters of subjects with metabolic derangements predisposing to hepatic steatosis and nonalcoholic steatohepatitis could facilitate genomic studies to identify risk factors for their development. Dunnigan-type familial partial lipodystrophy (FPLD) is an autosomal dominantly inherited disorder caused by mutations in the LMNA gene. Affected subjects have loss of subcutaneous fat from the extremities and symptoms similar to those characterizing the metabolic syndrome, including insulin resistance and dyslipidemia. The goal of this study was to determine the prevalence of steatosis in subjects with FPLD., Methods: We examined 18 subjects from six families with FPLD for mutations in LMNA and analyzed plasma lipid and serum glucose concentrations. Liver ultrasound and serum aminotransferase activities were used as indicators of steatosis or steatohepatitis. In two subjects, histological examination of hepatic tissue was performed., Results: All subjects had FPLD-causing mutations in LMNA. Plasma lipids were measured in 17 subjects, 16 of whom had hyperlipidemia and 14 presented with either documented insulin resistance or diabetes mellitus. Hepatic steatosis was present in 15 subjects who had ultrasound examinations and 9 of these had elevated serum aminotransferase activities. Liver biopsy confirmed steatosis in 2 subjects., Conclusions: Hepatic steatosis is part of the clinical phenotype of FPLD. This familial disorder may provide a human metabolic model system to facilitate genomic and environmental studies to determine risk factors for hepatic steatosis and nonalcoholic steatohepatitis.

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism. The disorder is caused by mutations in the ATP7B gene, encoding a copper transporting P-type ATPase. The worldwide incidence is in the order of 30 cases per million, with a gene frequency of 0.56% and a carrier frequency of 1 in 90. The increased number of Wilson disease patients in the island of Crete led us to study the spectrum of mutations in a small village close to the city of Heraklion, from where many patients have been referred during the last 25 years. In order to estimate the frequency of the disease, we firstly investigated the number of births and the number of WD patients in the village since 1978. Six out of 90 births were diagnosed as WD patients, presenting the highest prevalence of WD reported so far. Analysis of the whole gene in three Wilson disease patients, and relatives of a boy who died from WD, led to the detection of 4 different point mutations. Two of them were missense (p.I1148T and p.G1176R) and cosegregated in cis in the same patient; the other allele of this patient carried a nonsense mutation (p.Q289X). This is the first report in the literature of three mutations co-segregating in the same WD patient. The fourth mutation identified was a novel frameshift mutation (c.398delT) with documented cosegregation. When screening 200 inhabitants originating from the same area, 18 were found to be carriers of one of these mutations. These findings indicate the need for health education intervention, genetic counselling and newborn screening for the Wilson disease.

Aim: To analyse the impact of NOD2/CARD15 mutations on the clinical course of Crohn's disease patients from an eastern European country (Hungary)., Methods: We investigated the prevalence of the three common NOD2/CARD15 mutations (Arg702Trp, Gly908Arg, 1007finsC) in 148 patients with Crohn's disease, 128 patients with ulcerative colitis and 208 controls recruited from the University of Szeged, Hungary. In patients with Crohn's disease, the prevalence of NOD2/CARD15 mutations was correlated to the demographical and clinical parameters., Results: In total, 32.4% of Crohn's disease patients carried at least one mutant allele within NOD2/CARD15 compared to 13.2% of patients with ulcerative colitis (P = 0.0002) and to 11.5% of controls (P<0.0001). In Crohn's disease patients, the allele frequencies for Arg702Trp, Gly908Arg and 1007finsC were 7.1%, 3.0% and 10.8% respectively. Interestingly, only the 1007finsC mutation was associated with a distinct clinical phenotype. The patients positive for the 1007finsC mutation suffered more frequently from stenotic disease behaviour (P = 0.008). Furthermore, 51.9% of patients positive for the 1007finsC mutation underwent a surgical resection within the ileum compared to only 17.4% of patients without the 1007finsC mutation (P = 0.001). With respect to the other two mutations (Arg702Trp and Gly908Arg), no associations were found with all investigated clinical parameters., Conclusion: NOD2/CARD15 mutations are frequently found in Crohn's disease patients from Hungary. The 1007finsC mutation is associated with stenotic disease behaviour and frequent ileal resections.

Lamin A and C are components of the nuclear envelope, located at the nucleoplasmatic surface of the inner nuclear membrane within cells. Recently, mutations within LMNA encoding lamin A/C have been associated with various disease entities including cardiomyopathy. We screened heart transplant recipients suffering from dilated cardiomyopathy (DCM) with a positive family history of LMNA mutations. Four index patients and one relative belonging to four unrelated families carrying LMNA mutations were identified. The mutations p.Q355X and p.S22L have not been reported before, whereas p.R190W has already been reported in other studied DCM cohorts. In the patients of the present study, the mean age at manifestation of heart disease was 37.6 years (range 30-45 years), with progression to end-stage heart failure requiring transplantation at a mean age of 45.8 years (range 35-54 years). Three patients presented initially with atrial fibrillation. These data confirm the involvement of LMNA mutations in patients with DCM and extend the mutational spectrum of LMNA. The p.R190W mutation has been reported in different populations and may therefore be useful for analyzing the impact of a specific LMNA mutation on the phenotype of muscle disease., (Copyright 2005 S. Karger AG, Basel.)

Background and Aims: To evaluate genotyping for two DNA variants (c.1993+327C>T and c.1438+117G>A), recently found to be associated with adult-type hypolactasia, in the diagnosis of lactose intolerance., Methods: In total, 166 consecutive patients with gastrointestinal symptoms mimicking hypolactasia admitted to the clinic between March 2002 and December 2002 were included. Genotyping for the two DNA variants (c.1993+327C>T and c.1438+117G>A) and standard H2 breath test was performed., Results: Among 116 patients with positive H2 breath test, the c.1993+327C variant was detectable in 106 (91.4%) patients. Among 50 patients with negative H2 breath test, the c.1993+327C variant was seen in 2 patients. Sensitivity, specificity, positive and negative predictive values for the c.1993+327C variant were 91.4, 96.0, 98.1 and 82.8%, respectively. Genotyping for the c.1438+117G variant did not bring any additional information. Among 4 of the 10 patients with positive H2 breath test but negative for the c.1993+327C and the c.1438+117G variant,further evaluation revealed other diseases known to cause secondary hypolactasia such as celiac disease and short bowel syndrome., Conclusion: In symptomatic patients, genotyping for the DNA variant c.1993+327C is a reliable test for adult-type hypolactasia with high sensitivity and specificity and thus provides a new tool in the diagnostic workup of hypolactasia., (Copyright (c) 2005 S. Karger AG, Basel.)