Three-Year Follow-Up after Intrauterine mTOR Inhibitor Administration for Fetus with TSC-Associated Rhabdomyoma.

Tuberous sclerosis complex (TSC) is a multisystem disorder characterized by seizures, neuropsychiatric disorders, and tumors of the heart, brain, skin, lungs, and kidneys. We present a three-year follow-up of a patient with TSC-associated rhabdomyoma detected in utero. Genetic examination of the fetus and the parents revealed a de novo variant in the TSC2 gene (c.3037delG, p.Asp1013IlefsTer3). Oral everolimus was initiated in the pregnant mother to regress the fetal tumor, which was successful. To the best of our knowledge, there is very little information regarding the use of everolimus therapy during pregnancy. West-syndrome was diagnosed when the proband was four months old. The symptoms were well-manageable, however temporarily. Therapy-resistant focal seizures were frequent. The patient had good vitals and was under regular cardiological control, showed a balanced circulation, and did not require any medication. Subependymal giant cell astrocytoma (SEGA) identified by regular neuroimaging examinations remained unchanged, which may be a consequence of early intrauterine treatment. Early detection of the pathogenic TSC2 variant, followed by in utero administration of everolimus and early vigabatrin therapy, allowed the detection of a milder developmental delay of the proband. Our study emphasizes how early genetic testing and management of epilepsy are pivotal for proper neurodevelopmental impacts and therapeutic strategies.

Observation of a Possible Successful Treatment of DEPDC5-Related Epilepsy with mTOR Inhibitor.

The mechanistic target of the rapamycin signaling pathway serves as a central regulator of cell metabolism, growth, proliferation, and survival. In its regulation, the GTPase-activating protein activity toward Rags1 complex has an inhibitory effect. Mutations in genes encoding this complex protein are among the most common abnormalities in focal epilepsies. Within these mutations, the mutations affecting the DEPDC5 gene have been associated with different autosomal dominantly inherited epilepsy types. Due to the limited data available on mTOR inhibitor therapy in nontuberous sclerosis complex epileptic patients, here we present the clinical management of a patient with intractable epilepsy, skin hypopigmentation, and a DEPDC5 variant. The patient's phenotype is compatible with a nonlesional DEPDC5-related epileptic encephalopathy. We initiated compassionate, off-label everolimus treatment as the patient's condition continuously deteriorated. Due to bilateral pneumonia occurring at the beginning of the treatment, it was temporarily discontinued, and resumed in half the dose. Follow-up examination after 18 months showed a 90% reduction in seizure frequency with moderate improvement in attention function and nutritional status. Our case report emphasizes the importance of early genetic testing in patients with epileptic encephalopathy. Clinical consequences of mammalian target of rapamycin complex 1 (mTORC1) upregulation may be amenable to tailored treatment with mTOR inhibitors. A clinical trial on an international scale would be needed to draw conclusions.

TUBB4B gene mutation in Leber phenotype of congenital amaurosis syndrome associated with early-onset deafness.

Beta-tubulin 4B isotype is one of the subunits of microtubules encoded by TUBB4B gene on chromosome 9, which is responsible for the maintenance of microtubule stability. In humans, mutations in microtubule-encoding genes have been associated with several tubulinopathies with very heterogeneous symptoms. So far, only two missense mutations in TUBB4B gene have been found to have pathological implications in this disorder. Here we report a Hungarian family with three affected members, mother and her 12- and 14-year-old children, who suffer from ophthalmologic and hearing impairments probably due to c.1171C > T missense variant in the TUBB4B gene. The presented case is the second report, and unique in the literature because of three affected family members carrying the same mutation and the family provides evidence for a quite similar but not identical phenotype of LCAEOD in subjects carrying this mutation.

Xp11.2 Duplication in Females: Unique Features of a Rare Copy Number Variation.

Among the diseases with X-linked inheritance and intellectual disability, duplication of the Xp11.23p11.22 region is indeed a rare phenomenon, with less than 90 cases known in the literature. Most of them have been recognized with the routine application of array techniques, as these copy number variations (CNVs) are highly variable in size, occurring in recurrent and non-recurrent forms. Its pathogenic role is not debated anymore, but the information available about the pathomechanism, especially in affected females, is still very limited. It has been observed that the phenotype in females varies from normal to severe, which does not correlate with the size of the duplication or the genes involved, and which makes it very difficult to give an individual prognosis. Among the patients studied by the authors because of intellectual disability, epilepsy, and minor anomalies, overlapping duplications affecting the Xp11.23p11.22 region were detected in three females. Based on our detailed phenotype analysis, we concluded that Xp11.23p11.22 duplication is a neurodevelopmental disorder.

Gene testing in Treacher Collins syndrome / Génvizsgálat Treacher Collins-szindrómában

Összefoglaló. A Treacher Collins-szindróma a mandibulofacialis dysostosisok csoportjába tartozó kórkép. Fobb jellegzetességei a maxillaris és mandibularis dysostosis, az antimongoloid szemrések, az alsó szemhéj colobomája, illetve a vezetéses halláscsökkenés. A szindrómával járó tünetek egyénenként és családon belül is nagyon eltéroek lehetnek; legenyhébb formái csaknem észrevehetetlenek, míg a súlyosabb esetekben az életet veszélyezteto légúti szövodmények léphetnek fel. Hátterében az esetek dönto többségében a TCOF1-gén eltérései játszanak szerepet, mely eltérések autoszomális domináns módon öröklodnek. Esetbemutatásunk célja, hogy felhívjuk a figyelmet a genetikai vizsgálat elvégzésének fontosságára olyan, klinikailag jól felismerheto tünetegyüttes, mint a Treacher Collins-szindróma esetén. Bár a betegség a klinikai kép alapján diagnosztizálható, az ismétlodés kockázatát csak úgy tudjuk pontosan meghatározni, ha ismerjük a családtagok genotípusát. A bemutatott család több tagjánál kimutatható volt a TCOF1-gén mutációja, annak ellenére, hogy klinikai tünetük nem volt. A jelenség magyarázata az inkomplett penetrancia, azaz a hibás gén fenotípusosan nem kerül kifejezodésre. Orv Hetil. 2020; 161(52): 2201-2205. Summary. Treacher Collins syndrome belongs to the group of mandibulofacial dysostoses. Its main features are maxillary and mandibular dysostosis, downward-slanting palpebral fissures, coloboma of the lower eyelid and conductive hearing loss. The symptoms associated with the syndrome can vary greatly from individual to individual and within the family. In its mildest form, the syndrome is almost imperceptible, and when severe, life-threatening respiratory complication can occur. TCOF1 is the major gene involved with an autosomal dominant mode of inheritance. The purpose of our case study is to draw attention to the importance of performing genetic testing in a clinically recognizable disorder such as Treacher Collins syndrome. Although the disease can be diagnosed based on the clinical symptoms, the risk of recurrence can only be accurately determined if the genotype of the family members is known. Several members of the presented family had a mutation in the TCOF1 gene despite having no clinical symptoms. The explanation for this phenomenon is incomplete penetrance, i.e., the defective gene is not expressed in the phenotype. Orv Hetil. 2020; 161(52): 2201-2205.

Investigating the genetic characteristics of the Csangos, a traditionally Hungarian speaking ethnic group residing in Romania.

Csango people are an East-Central European ethnographic group living mostly in the historical region of Moldavia, Romania. Their traditional language, the Csango is an old Hungarian dialect, which is a severely endangered language due to language shift. Their origin is still disputed among experts and there are many hypotheses since the 19th century. Previous genetic studies found connection with ethnic groups living in Hungary and provided evidence which might support their Hungarian origin. Another study found Inner Asian Altaic ancestry in their genetic makeup. The goal of this study was to analyze the genetic characteristics of the Csango people by comparing their genetic characteristics to contemporary Eurasian populations based on genome-wide autosomal marker data. Our findings suggest that genetic affinity of Csangos to Hungarians is more significant than to Romanians. They also have a detectable connection with Central-Asian and Siberian Turkic ethnic groups. Besides the presumable Middle Eastern/Central-Asian Turkic ancestry, Csangos show ~4% Turkic ancestry from Central Asia/Siberia, which makes them unique in comparison to all other East-Central European populations investigated in this study. The admixture that resulted in this Turkic ancestry could have occurred 30-40 generations ago, which date interval corresponds to Hungarian historical events regarding their migration and the conquest of the Carpathian basin.

Marked Differences of Haplotype Tagging SNP Distribution, Linkage, and Haplotype Profile of APOA5 Gene in Roma Population Samples.

Roma people are underprivileged, neglected population worldwide, with severe healthcare problems. They have significantly increased prevalence of cardiovascular morbidity, presumably related to their poor social status, alcohol consumption and smoking habits. Assuming that genetic background also plays a role in their susceptibility for cardiovascular diseases, we hypothesized that APOA5 gene polymorphisms, an important role-player in lipid metabolism and in the development of metabolic syndrome and cardio/cerebrovascular events, may also be involved. We examined four APOA5 polymorphisms in 363 Roma and 404 Hungarian DNA samples. For rs662799, rs2266788, rs207560 and rs3135506 we found elevated plasma triglyceride levels in the risk allele carriers compared to non-carriers in both populations. At least a two-fold significant increase was detected in minor allele frequencies in Roma when compared to Hungarians, except the rs2266788 variant. Haplotype analysis revealed significant increase of APOA5*2, APOA5*4 in Roma, as opposed to the higher levels of APOA5*5 found in Hungarians. Different linkage disequilibrium was found between rs207560 and rs3135506 variants in Roma compared to Hungarians. The profound differences observed in almost all APOA5 polymorphisms in Roma require special attention, since these variants are known to associate with cardio/cerebrovascular susceptibility.

Functional variants of lipid level modifier MLXIPL, GCKR, GALNT2, CILP2, ANGPTL3 and TRIB1 genes in healthy Roma and Hungarian populations.

The role of triglyceride metabolism in different diseases, such as cardiovascular or cerebrovascular diseases is still under extensive investigations. In genome-wide studies several polymorphisms have been reported, which are highly associated with plasma lipid level changes. Our goal was to examine eight variants: rs12130333 at the ANGPTL3, rs16996148 at the CILP2, rs17321515 at the TRIB1, rs17145738 and rs3812316 of the MLXIPL, rs4846914 at GALNT2, rs1260326 and rs780094 residing at the GCKR loci. A total of 399 Roma (Gypsy) and 404 Hungarian population samples were genotyped using PCR-RFLP method. Significant differences were found between Roma and Hungarian population samples in both MLXIPL variants (C allele frequency of rs17145738: 94.1% vs. 85.6%, C allele frequency of rs3812316: 94.2% vs. 86.8% in Romas vs. in Hungarians, p < 0.05), in ANGPTL3 (T allele frequency of rs1213033: 12.2% vs. 18.5% in Romas vs. Hungarians, p < 0.05) and GALNT2 (G allele frequency of rs4846914: 46.6% vs. 54.5% Romas vs. in Hungarians, p < 0.05), while no differences over SNPs could be verified and the known minor alleles showed no correlation with triglyceride levels in any population samples. The current study revealed fundamental differences of known triglyceride modifying SNPs in Roma population. Failure of finding evidence for affected triglyceride metabolism shows that these susceptibility genes are much less effective compared for example to the apolipoprotein A5 gene.

Retrospective assessment of the most common mitochondrial DNA mutations in a large Hungarian cohort of suspect mitochondrial cases.

Prevalence estimations for mitochondrial disorders still vary widely and only few epidemiologic studies have been carried out so far. With the present work we aim to give a comprehensive overview about frequencies of the most common mitochondrial mutations in Hungarian patients. A total of 1328 patients were tested between 1999 and 2012. Among them, 882 were screened for the m.3243A > G, m.8344A > G, m.8993T > C/G mutations and deletions, 446 for LHON primary mutations. The mutation frequency in our cohort was 2.61% for the m.3243A > G, 1.47% for the m.8344A > G, 17.94% for Leber's Hereditary Optic Neuropathy (m.3460G > A, m.11778G > A, m.14484T > C) and 0.45% for the m.8993T > C/G substitutions. Single mtDNA deletions were detected in 14.97%, while multiple deletions in 6.01% of the cases. The mutation frequency in Hungarian patients suggestive of mitochondrial disease was similar to other Caucasian populations. Further retrospective studies of different populations are needed in order to accurately assess the importance of mitochondrial diseases and manage these patients.

Hodgkin disease therapy induced second malignancy susceptibility 6q21 functional variants in roma and hungarian population samples.

Patients treated successfully for pediatric Hodgkin's lymphoma are known to develop secondary malignancies; care is already taken in treatment to prevent this adverse effect. Recent GWAS study identified rs4946728 and rs1040411 noncoding SNPs located between PRDM1 and ATG1 genes on chromosome 6q21 as risk factors for secondary malignancies in patients formerly treated with radiotherapy for pediatric Hodgkin disease. We investigated the allele frequencies of these two SNPs in biobanked, randomly selected DNA of average, apparently healthy Hungarians (n = 277) and in samples of Roma (n = 279) population living Hungary. The risk allele frequency for rs4946728 was 79.4 % in Hungarian and 83.5 % in Roma samples, while for rs1040411 it was 56.4 % in Hungarian and 55.8 % in Roma samples. These values are quite similar in the two populations, and are rather high. The values are higher than those frequencies observed in the controls (rs4946728: 59.1 % and rs1040411: 39.6 %, p < 0.05), and are in the range of the cases (86 % and 68.2 %, respectively) of the above original GWAS study. Our findings suggest, that beside the already taken precautions, genetic characterization of Hungarian pediatric Hodgkin patients seems to be advantageous prior to the treatment of their disease.

Association of myasthenia gravis with polymorphisms in the gene of histamine N-methyltransferase.

INTRODUCTION: Histamine N-methyltransferase (HNMT) is the main metabolizing enzyme of histamine. Histamine modulates immune responses and plays a role in the pathogenesis of autoimmune disorders. METHODS: The non-synonymous HNMT C314T polymorphism and the A939G single-nucleotide polymorphism (SNP) influencing HNMT mRNA stability were genotyped in 213 patients with myasthenia gravis (MG) and 342 healthy controls. RESULTS: The carrier frequency of the A allele of the A939G SNP was over-represented among patients with anti-AchR and anti-Titin antibodies (P = 0.05 and P = 0.004, respectively); the presence of the minor G allele was protective against anti-AchR and anti-Titin positive MG (OR = 0.67 and OR = 0.54, respectively). The combination of the G allele carrier status with wild-type C314C homozygosity was also protective against MG (OR = 0.55, P = 0.008) and against the development of anti-AchR antibodies (OR = 0.37, P = 0.01). DISCUSSION: The A939G HNMT polymorphism is associated with autoimmune MG, while no association with C314T SNP was found.

Non-syndromic Hearing Impairment in a Hungarian Family with the m.7510T>C Mutation of Mitochondrial tRNA(Ser(UCN)) and Review of Published Cases.

The m.7510T>C mitochondrial DNA (mtDNA) mutation is a tRNA(Ser(UCN)) alteration leading to matrilineal isolated hearing impairment. The current paper reviews the available reports on the m.7510T>C mtDNA mutation, with special attention to phenotypic variations and haplogroup background. A Hungarian family, the fourth family reported in the literature, is presented, in which analysis of three generations with bilateral isolated hearing loss revealed the m.7510T>C tRNA(Ser(UCN)) mutation in homoplasmic form in the affected members. Haplogroup analysis verified an unnamed subgroup of mitochondrial haplogroup H. Previously reported Spanish and North American Caucasian families belong to different subgroups of haplogroup H. Analyzing our biobank of Hungarian patients with sensorineural hearing loss, we did not detect this mutation in any other patient, nor was it found in Caucasian haplogroup H control samples. Comparing the cases reported so far, there is interfamilial variablity in the age of onset, accompanying symptoms, and haplogroup background. Our case adds further genetic evidence for the pathogenicity of the m.7510T>C mutation and underlines the need to include full mtDNA sequencing in the screening for unexplained hearing loss.

[Significance of thiopurine s-methyltransferase gene test in a clinical case]. / Thiopurin s-metil-transzferáz gén vizsgálatának jelentosége egy eset kapcsán.

Thiopurine s-methyltransferase enzyme is responsible for the metabolism of immunosuppressant thiopurines, which are used in inflammatory bowel diseases, acute lymphoblastic leukemia and autoimmune diseases. Because of the relative narrow therapeutic index of thiopurines serious or life threatening side effects can occur. A total of 28 variant alleles of the gene coding for the thiopurine s-methyltransferase enzyme are responsible for altered catalytic activity of the enzyme. Patients with one non-functional (heterozygous) allele have intermediate, while those with two non-functional (homozygous) alleles have low enzyme activity. Using polymerase chain reaction/restriction fragment length polymorphism and direct DNA sequencing the authors determined the G238C, G460A and A719G polymorphisms of the thiopurine s-methyltransferase gene in a child with Crohn's disease who developed thiopurine-induced severe agranulocytosis. The presence of the G460A and A719G polymorphic alleles in homozygous forms were detected which corresponded to the *3A variant allele. This variant has been shown to be associated with lower enzyme activity and low amount of the enzyme resulting in thiopurine toxicity and agranulocytosis. These findings underline the need for genotyping of the thiopurine s-methyltransferase variants prior to thiopurine treatment.

Common functional variants of APOA5 and GCKR accumulate gradually in association with triglyceride increase in metabolic syndrome patients.

The common functional variants of the apolipoprotein A5 (APOA5) and the glucokinase regulatory protein genes (GCKR) have been shown to associate with increased fasting triglyceride (TG) levels. Albeit the basic association has been extensively investigated in several populations of different origin, less is known about quantitative traits of them. In our study accumulation rates of four APOA5 (T-1131, IVS3 + G476A, T1259C and C56G) and two GCKR (C1337T and rs780094) functional SNPs were analyzed in patients stratified into four TG quartile groups. Randomly selected 325 metabolic syndrome patients were separated into four quartile (q) groups based on the TG levels as follows q1: TG <1.38 mmol/l; q2: 1.38-1.93 mmol/l; q3: 1.94-2.83 mmol/l; and q4: TG >2.83 mmol/l. We observed significant stepwise increase of prevalence rates of minor allele frequencies in the four plasma TG quartiles for three APOA5 SNPs: -1131C (q1: 4.94%; q2: 8.64%; q3: 11.6%; q4: 12.3%), IVS3 + 476A (q1: 4.32%; q2: 7.4%; q3: 10.36%; q4: 11.1%), and 1259C (q1: 4.94%; q2: 7.41%; q3: 10.4%; q4: 11.7%). The haplotype analysis revealed, that the frequency of APOA5*2 haplotype gradually increased in q2, q3 and q4 (q1: 9.87%; q2: 14.8%; q3: 18.3%; q4: 21%). The distribution of the homozygotes of the two analyzed GCKR variants resembled to the APOA5 pattern. Contrary to the hypothetically predictable linear association coming from the current knowledge about the APOA5 and GCKR functions, the findings presented here revealed a unique, TG raise dependent gradual accumulation of the functional variants of in MS patients. Thus, the findings of the current study serve indirect evidence for the existence of rare APOA5 and GCKR haplotypes in metabolic syndrome patients with higher TG levels, which contribute to the complex lipid metabolism alteration in this disease.

Triglyceride level-influencing functional variants of the ANGPTL3, CILP2, and TRIB1 loci in ischemic stroke.

Stroke is a common multifactorial disease, and the third leading cause of death worldwide, which results in serious long-term mental and physical disability among survivors. The role of affected triglyceride metabolism in the development of ischemic stroke is under extensive investigations. Here, we examined three SNPs, rs12130333 located within the ANGPTL3 locus; rs16996148 residing at the CILP2 gene locus; and rs17321515 at the TRIB1 locus, which were originally reported in association with decreased triglyceride levels; therefore, we investigated their possible protective effect against the development of ischemic stroke. A total of 459 Caucasian stroke patients, stratified as large-vessel, small-vessel, and mixed stroke groups, and 168 control subjects were genotyped using PCR-RFLP methods. As a result, we could not detect any differences in triglyceride or total cholesterol levels in relation to any allelic variants of rs16996148, rs17321515, or rs12130333 SNPs. No correlation was found between the minor alleles rs16996148-T (P = 0.881), rs17321515-G (P = 0.070), or rs12130333-T allele (P = 0.757) and the risk for development of stroke. The data presented here suggest different scale of effect of triglyceride modifier alleles and also their variable susceptibility or protective nature.

[Genetics of ischemic stroke: where are we now?]. / Ischaemiás stroke genetikai háttere: Hol tartunk most?

As stroke is the third leading cause of death after heart failure and tumors worldwide, cerebrovascular diseases reached substantial attention. In the past few years, significant progression has been seen in identification of genetic variants in the background of stroke and other cerebrovascular and cardiovascular events. Examination of these variants is a new approach to recognize pathogenesis of disorders that hopefully helps in future prevention and prospects of screening and, optimistically, it contributes to special care of patients susceptible for stroke. In the background of ischemic stroke several genetic variants have been identified, which localize in genes encoding proteins involved in hemostasis, renin-angiotensin system and lipid metabolism. The number of these variants exponentially increases permanently due to rapid spreading of genome wide association studies. The goal of this review is to summarize the results of genetic studies on ischemic stroke. Here the authors focus on genetic variants which can have major role in personalized medicine and prevention of stroke.

Haplotype analysis of the apolipoprotein A5 gene in obese pediatric patients.

OBJECTIVE: Apolipoprotein A5 (APOA5) gene variants have been shown to be associated with elevated TG levels; the T-1131C (rs662799) variant has been reported to confer risk for the metabolic syndrome in adult populations. Little is known about the APOA5 variants in pediatric population, no such information is available for pediatric obesity at all. Here we examined four haplotype-tagging polymorphisms (T-1131C, IVS3 + G476A [rs2072560], T1259C [rs2266788] and C56G [rs3135506]) and studied also the frequency of major naturally occurring haplotypes of APOA5 in obese children. METHODS: The polymorphisms were analyzed in 232 obese children, and in 137 healthy, normal weight controls, using PCR-RFLP methods. RESULTS: In the pediatric patients we could confirm the already known adult subjects based association of -1131C, IVS3 + 476A and 1259C variants with elevated triglyceride concentrations, both in obese patients and in the controls. The prevalence of the APOA5*2 haplotype (containing the minor allele of T-1131C, IVS3 + G476A and T1259C SNPs together) was 15.5% in obese children, and 5.80% in the controls (p<0.001); multiple logistic regression analysis revealed that this haplotype confers susceptibility for development of obesity (OR=2.87; 95% CI: 1.29-6.37; p≤0.01). By contrast, the APOA5*4 haplotype (with -1131C alone) did not show similar associations. Our findings also suggest that the APOA5*5 haplotype (1259C alone) can be protective against obesity (OR=0.25; 95% CI: 0.07-0.80; p<0.05). CONCLUSIONS: While previous studies in adults demonstrated, that the APOA5 -1131C minor allele confers risk for adult metabolic syndrome, here we show, that the susceptibility nature of this SNP restricted to the APOA5*2 haplotype in pediatric obese subjects.

Stepwise positive association between APOA5 minor allele frequencies and increasing plasma triglyceride quartiles in random patients with hypertriglyceridemia of unclarified origin.

Apolipoprotein A5 (ApoA5) gene and its protein product play a central role in the complex regulation of circulating triglyceride levels in humans. Naturally occurring variants of the apolipoprotein A5 gene have been associated with increased triglyceride levels and have been found to confer risk for cardiovascular diseases. In our study, four polymorphisms, the T-1131C, IVS3+G476A, T1259C, and C56G alleles of APOA5 were analyzed in a total of 436 patients by polymerase chain reaction-restriction fragment length polymorphism methods. The randomly selected patients were classified into four quartile (q) groups based on triglyceride levels (q1: TG<1.31 mmol/l; q2: 1.31-2.90 mmol/l; q3: 2.91-4.85 mmol/l; q4: TG>4.85 mmol/l). We observed significant stepwise increasing association between the four APOA5 minor allele carrier frequencies and plasma triglyceride quartiles: -1131C (q1: 4.44%; q2: 8.95%; q3: 12.9%; q4: 20.6%), IVS3 + 476A (q1: 4.44%; q2: 5.79%; q3: 11.1%; q4: 19.7%), 1259C (q1: 4.44%; q2: 6.84%; q3: 11.1%; q4: 20.6%) and 56G (q1: 5.64%; q2: 6.31%; q3: 11.16%; q4: 11.9%). The serum total cholesterol and high density lipoprotein-cholesterol levels also showed allele-dependent differences in the quartiles. The findings presented here revealed a special arrangement of APOA5 minor alleles in patients with different serum triglyceride ranges in Hungarians.

Genetic variability and haplotype profile of MDR1 (ABCB1) in Roma and Hungarian population samples with a review of the literature.

The genetic variability, haplotype profile and ethnic differences of MDR1 polymorphisms in healthy Roma and Hungarian populations were analyzed and the results were compared with those of other populations available from the literature. Healthy subjects (465 Roma and 503 Hungarian) were genotyped for C1236T, G2677T/A and C3435T variants of MDR1 by PCR-RFLP assay. Differences were found between the Roma and Hungarian populations in the frequencies of MDR1 1236 CC (20.7 vs. 33.2%) and TT genotypes (30.8 vs. 21.9%), in T allele frequency (0.551 vs. 0.443) (p < 0.002), and in 3435T allele frequency (0.482 vs. 0.527, p < 0.04). Furthermore, the frequency of CGC, CGT and CTT haplotypes was significantly higher in the Hungarian population than in Roma (41.4 vs. 35.3%, 9.04 vs. 6.02% and 2.88 vs. 1.08%, respectively; p < 0.009), whereas the frequency of TGC and TTC haplotypes was higher in the Roma population than in the Hungarian (7.31 vs. 1.68% and 6.67 vs. 2.08%, respectively; p < 0.001). The prevalence of MDR1 polymorphisms in the Hungarian population is similar to that of other European populations; however, some differences were observed in the haplotype structures. In contrast, the Roma population differs from Hungarians, from Caucasians and from populations from India in the incidence of MDR1 common variants and haplotypes.