Dwie mutacje w jednym genie dystrofiny

Background and purpose Duchenne/Becker muscular dystrophies (DMD/BMD) lead to progressive irreversible muscle deterioration caused by recessive mutations in the dystrophin encoding gene (Xp21.1). Approximately 60% of mutations are deletions, 10% are duplications and the remaining 30% are point mutations. The aim of the study is to present the rare occurrence of two pathogenic mutations (deletions or duplications) in one allele of the dystrophin gene. Material and methods DNA of patients from 1364 DMD/BMD families was tested. Two techniques – PCR-multiplex and multiplex ligation-dependent probe amplification – were used to search for mutations in the dystrophin gene. Results Deletion was detected in 648 families and duplication was found in 74 families (analysis in progress). In two families, presence of two mutations in one gene was documented – in the first family two deletions were found (exons 45–49 and 60–61), and in the second family two duplications were detected (exons 2–7 and 50–59). One of the deletions disrupted the reading frame, and the other deletion retained the reading frame. Both duplications also retained the reading frame of the gene but in both families the disease took a severe course (DMD). In the family with two duplications prenatal diagnosis was also carried out, and carriership of both mutations was discovered in the female fetus. Conclusions In the analyzed group of DMD/BMD families, the frequency of combined occurrence of two mutations in one gene was 2 per 722 (0.3%). The phenomenon of detected non-contiguous deletions and duplications is presented together with 31 similar cases published so far.Wstęp i cel pracy Dystrofia mięśniowa Duchenne'a/Beckera (DMD/BMD) jest związana z postępującym i nieodwracalnym zanikiem mięśni wywołanym recesywnymi mutacjami w genie dystrofiny (Xp21.1). Szacuje się, że 60% mutacji stanowią delecje, a 10% – duplikacje; pozostałe 30% mutacji ma charakter punktowy. Celem pracy jest przedstawienie rzadkich przypadków współwystąpienia w jednym allelu genu dystrofiny dwóch chorobotwórczych mutacji – delecji lub duplikacji. Materiał i metody Badano DNA pacjentów z 1364 rodzin skierowanych z podejrzeniem DMD lub BMD. Mutacji poszukiwano, używając dwóch technik: PCR-multiplex i MLPA (multiplex ligation-dependent probe amplification). Wyniki W 648 rodzinach wykryto delecję, a w 74 rodzinach – duplikację (badania w toku). W dwóch rodzinach udokumentowano łączne wystąpienie w jednym genie dystrofiny dwóch mutacji – w pierwszej rodzinie w jednym allelu wykryto dwie delecje (eksony 45–49 i 60–61), a w drugiej rodzinie dwie duplikacje (eksony 2–7 i 50–59). Jedna z delecji naruszała fazę odczytu, druga zaś ją zachowywała; obie duplikacje zachowywały fazę odczytu, jednak w obu rodzinach choroba przybierała ostrą postać (DMD). W rodzinie, w której wykryto dwie duplikacje, wykonano diagnostykę prenatalną, stwierdzając u płodu płci żeńskiej nosicielstwo obu mutacji. Wnioski W analizowanej grupie rodzin z delecją lub duplikacją częstość łącznego wystąpienia dwóch mutacji wyniosła 2 na 722 (0,3%). Zjawisko wykrytych nieciągłych delecji i duplikacji przedstawiamy w zestawieniu z opisanymi dotychczas 31 podobnymi przypadkami

Nieinwazyjna diagnostyka prenatalna trisomii 21,18 i 13 z wykorzystaniem wolnego pozakomórkowego DNA płodu

Trisomy 21, 18 and 13 are the most common trisomies diagnosed in newborns. Screening methods consist of ultrasound and maternal serum markers. High risk for fetal aneuploidies is an indication for routine karyotyping, which requires collection of fetal tissue through amniocentesis or chorionic villous sampling. They are invasive procedures and carry a potential risk of miscarriage. The discovery of cell free fetal DNA (cffDNA) in maternal blood offered new opportunities for noninvasive prenatal diagnosis. The fraction of cell-free fetal DNA in total pool of cell-free DNA in maternal plasma is very low, therefore the analysis of cffDNA is very challenging. The introduction of massive parallel sequencing has enabled the application of noninvasive prenatal testing in the clinical practice and a variety of recent studies have proven its high efficacy in diagnosing common aneuploidies.Trisomie chromosomów 21, 18 i 13 należą do najczęściej diagnozowanych aberracji chromosomowych u noworodków. Obecnie w celu oceny ryzyka ich wystąpienia wykonuje się badanie ultrasonograficzne oraz testy biochemiczne. Stwierdzenie na podstawie testów przesiewowych wysokiego ryzyka trisomii u płodu jest wskazaniem do oznaczenia kariotypu klasyczną metodą cytogenetyczną, która niesie za sobą potrzebę pobrania materiału genetycznego płodu. Badania inwazyjne (amniopunkcja, biopsja trofoblastu) obarczone są ryzykiem straty ciąży. Wykrycie obecności wolnego pozakomórkowego DNA płodu (cffDNA – cell free fetal DNA) we krwi matki zapoczątkowało szereg badań nad możliwościami jego wykorzystania w diagnostyce prenatalnej. cffDNA stanowi jednak tylko niewielką część całkowitej puli wolnego DNA we krwi matki, dlatego jego analiza jest trudna. Wprowadzenie metody masywnego równoległego sekwencjonowania umożliwiło zastosowanie nieinwazyjnych testów w praktyce klinicznej, a prowadzone w ostatnich latach liczne badania dowiodły skuteczności metody w diagnostyce prenatalnej trzech najczęściej występujących trisomii

Multiplex Ligation-dependent Probe Amplification (MLPA) – new possibilities of prenatal diagnosis

Multiplex Ligation-dependent Probe Amplification (MLPA) is a relatively new method of molecular diagnosis. It enables a relative quantitative assessment of up to 50 different PCR amplicons in one reaction by the use of a very small amount of examined DNA. Nowadays MLPA is becoming a very helpful tool in prenatal diagnosis and is widely used for the detection of aneuploidies, familial single gene disorders, common microdeletion syndromes, sub-telomeric alterations and identification of marker chromosomes in fetuses. This review demonstrates possible applications of MLPA in prenatal diagnosis

Postać dziedziczna choroby prionowej w Polsce

Background and purpose The aim of the study was to perform molecular analysis in a group of patients affected with prion disease. Diagnosis was based on results of clinical and/or histopathological examination of the brain. This is the largest investigation of this type performed so far in Poland. Material and methods Analysed material contained 36 cases of prion disease, including 35 cases of Creutzfeldt-Jakob disease and one case of Gerstmann-Sträussler-Scheinker disease, as well as two familial cases initially suspected of Huntington disease and Alzheimer disease. The control group consisted of 87 subjects. The most frequent known mutations in the PRNP gene were looked for, namely those in codons 102, 117, 178, 200, 217 and OPRI; the polymorphism Met/Val in codon 129 was also analysed. The methods applied were PCR-RFLP and DNA sequencing. Results The following mutations were found: E200K in 5 families, P102L in one family (previously identified), D178N in one family and 6OPRI in one family. Overall, mutations were detected in 17 persons (including 8 preclinical ones) from 8 pedigrees. Highly significant difference of codon 129 Met/Val heterozygosity frequencies was found between the affected subjects and the controls. Frequency of the familial form of prion disease in the material analysed was 14%. Conclusions Screening for mutations in the PRNP gene should be performed in all diagnosed cases of prion disease and cases of familial occurrence of early onset dementia of unknown aetiology. Families with identified mutations should be offered genetic counselling and informed of risks of blood and organs’ donation.Wstęp i cel pracy Celem pracy była analiza molekularna w grupie osób dotkniętych chorobą prionową, rozpoznaną na podstawie objawów klinicznych i/lub wyniku badania neuropatologicznego mózgu. Było to największe tego typu badanie przeprowadzone dotychczas w Polsce. Materiał i metody W skład analizowanego materiału weszło 36 przypadków choroby prionowej, w tym 35 przypadków choroby Creutzfeldta-Jakoba i jeden przypadek choroby Gerstmanna-Sträusslera-Scheinkera, a także dwa przypadki rodzinne podejrzane o chorobę Huntingtona i chorobę Alzheimera oraz grupa kontrolna (87 osób). Poszukiwano najczęstszych mutacji w genie PRNP: wkodonach 102, 117, 178, 200, 217 i OPRI. Kodon 129 analizowano również pod kątem zygotyczności (walina/metionina). Stosowano metodę PCR-RFLP i sekwencjonowanie. Wyniki Wykryto mutacje: E200K – pięć rodzin, P102L – jedna rodzina (wcześniej zidentyfikowana), D178N – jedna rodzina, 6OPRI – jedna rodzina. Łącznie stwierdzono mutację w 8 rodowodach u 17 osób, w tym u 8 osób w fazie przedobjawowej. Zaobserwowano także bardzo istotną różnicę w częstości występowania heterozygotyczności Met/Val pomiędzy grupą badaną i grupą kontrolną. Częstość dziedzicznej postaci choroby prionowej w analizowanym materiale wynosi 14%. Wnioski Mutacji w genie PRNP należy poszukiwać we wszystkich przypadkach choroby prionowej oraz w przypadkach rodzinnie występującego otępienia o wczesnym początku i niewyjaśnionej etiologii. Przebieg kliniczny i zmiany neuropatologiczne w niektórych przypadkach dziedzicznych chorób prionowych mogą się różnić od spotykanych najczęściej w sporadycznej postaci choroby. Rodziny ze stwierdzoną mutacją winny być objęte poradnictwem genetycznym i poinformowane o zagrożeniu związanym z dawstwem krwi i narządów do przeszczepienia

MLPA based detection of mutations in the dystrophin gene of 180 Polish families with Duchenne/Becker muscular dystrophy

Duchenne/Becker muscular dystrophy (DMD/BMD) is a recessive, X-linked disorder caused by a mutation in the dystrophin gene. Deletions account for approximately 60–65% of mutations, duplications for 5–10%. The remaining cases are mainly point mutations. According to Monaco theory clinical form of the disease depends on maintaining or disrupting the reading frame. The purpose of the study was to determine frequency and location of deletions and duplications in the dystrophin gene, to determine the compliance between maintaining/disrupting the reading frame and clinical form of the disease and to check the effectiveness of MLPA (multiplex ligation-dependent probe amplification) in the detection of these mutations in hemizygous patients and heterozygous female carriers. The material is composed of combined results of molecular diagnosis carried out in years 2009–2012 in 180 unrelated patients referred with the diagnosis of DMD/BMD tested by use of MLPA. We identified 110 deletions, 22 duplication (in one patient two different duplications were detected) and 2 point mutations. Deletions involved mainly exons 45–54 and 3–21, whereas most duplications involved exons 3–18. The compliance with Monaco theory was 95% for deletions and 76% for duplications. Most of mutations in the dystrophin gene were localized in the hot spots – different for deletions and duplications. MLPA enabled their quick identification, exact localization and determination whether or not they maintained or disrupted the reading frame. MLPA was also effective in detection of deletions and duplications in female carriers

Nieinwazyjna diagnostyka prenatalna najczęstszych aneuploidii na podstawie płodowego DNA we krwi matki – doniesienie wstępne

Objectives: The aim of the study was to present initial results of non-invasive prenatal diagnosis of common aneuploidies of chromosomes 21, 18 and 13 based on cell-free fetal DNA in maternal serum in high-risk patients, and to compare the results with routine karyotyping. Material and methods: Before the invasive procedure, 10 ml of peripheral blood from 10 patients was collected to isolate cell-free fetal DNA and to perform a non-invasive fetal trisomy test (NIFTY provided by Beijing Genomics Institute, BGI, Shenzen, China). Results: Three out of 10 samples showed an abnormal karyotype in traditional karyotyping. There were 9 conclusive NIFTY results. NIFTY detected 1 out of 2 trisomies 18. The quantity of cell-free fetal DNA in maternal plasma in the second probe with trisomy 18 was unsatisfactory for a conclusive NIFTY result. In 1 case traditional karyotyping revealed mosaicism impossible to detect with NIFTY.Cel pracy: Wstępne przedstawienie wyników wykorzystania płodowego DNA z krwi matki w nieinwazyjnej diagnostyce prenatalnej aneuploidii chromosomów 21, 18 i 13 u pacjentek wysokiego ryzyka aberracji chromosomowych u płodu oraz ich porównanie z wynikami klasycznego badania cytogenetycznego. Materiał i metoda: Od dziesięciu ciężarnych pacjentek przed wykonaniem badania inwazyjnego pobrano 10 ml krwi obwodowej celem izolacji pozakomórkowego DNA płodu (cffDNA – cell free fetal DNA) i przeprowadzenia testu NIFTY (Non-Invasive Fetal Trisomy Test; Beijing Genomics Institute, BGI, Shenzen, China). Wyniki: W trzech z dziesięciu próbek w badaniu cytogenetycznym stwierdzono nieprawidłowy kariotyp płodu. Na podstawie płodowego DNA z dziewięciu próbek osocza za pomocą testu NIFTY udało się określić ryzyko aneuploidii u płodu. Wysokie ryzyko aneuploidii prawidłowo oceniono w jednym z dwóch przypadków trisomii chromosomu 18. W drugiej probce podejrzewano wysokie ryzyko trisomii chromosomu 18, ale ilość cffDNA była zbyt mała, aby wynik spełniał standardy producenta. Wykryty w badaniu cytogenetycznym kariotyp mozaikowy z założenia nie mógł zostać wykryty metodą nieinwazyjną. Wnioski: Płodowe DNA z krwi matki może służyć do wykrywania najczęstszych aneuploidii u płodu. Test mógłby posłużyć jako badanie przesiewowe II rzutu, prowadząc do zmniejszenia liczby pacjentek poddawanych badaniu inwazyjnemu

Evaluation of the frequency of ADIPOQ c.45 T>G and ADIPOQ c.276 G>T polymorphisms in adiponectin coding gene in girls with anorexia nervosa

Introduction: Anorexia nervosa (AN) is a serious chronic psychosomatic disorder, the essence of which are attempts by the sufferer to obtain a slim silhouette by deliberate weight loss (restrictive diet, strenuous physical exercise, provoking vomiting). The aetiology of this disorder is multifactorial. Genetic factors that influence the predisposition to AN have been sought. A broad meta-analysis points to a strong genetic correlation between AN and insulin resistance. Adiponectin (ADIPO) increases insulin sensitivity. In our pilot study we demonstrated that the TT genotype in locus ADIPOQ c.276 G>T of the ADIPO gene and a higher concentration of ADIPO in blood serum occurred significantly more frequently in 68 girls suffering from AN than in 38 healthy girls. The objective of this study was to evaluate the frequency of the occurrence of ADIPOQ c.45 T>G and ADIPOQ c.276 G>T in the ADIPO gene in a larger cohort of girls with AN and healthy girls, as well as an analysis of correlations between variants of the aforementioned polymorphisms and the levels of ADIPO in blood serum. Material and methods: The study covered 472 girls (age: 11–19 years): 308 with the restrictive form of AN (AN) and 164 healthy girls (C). The level of ADIPO in blood serum was determined by means of the ELISA method on a Bio-Vendor, LLC (Asheville, North Carolina, USA). The DNA isolation was carried out by means of Genomic Mini AX BLOOD (SPIN). The PCR reaction was carried out in a ThermoCycle T100 thermocycler. 80–150 ng of the studied DNA and relevant F and R starters were added to the reaction mixture. The reaction products were subjected to digestion by restriction enzymes and separated on agarose gels (RFLP). Results: The distribution of genotypes in the polymorphic site ADP c.45 of the ADIPO gene and ADP c.276 was similar in both groups. In both groups the T allele was most frequent in locus ADIPOQ c.45 and the G allele in locus ADIPOQ c.276. In all the study subjects collectively (AN and C) a statistically significant negative correlation between the levels of ADIPO in blood serum on one hand and body weight (r = –0.46; p < 0.0001) and BMI (r = –0.67; p < 0.0001) on the other was demonstrated. Exclusively in the AN group a significant correlation between the level of ADIPO in blood and the distribution of TG, TT, and GG alleles in loci ADIPOQ c.45 and ADIPOQ c.276 was demonstrated (p = 0.0052 and p < 0.0001, respectively). Conclusions: The genotype in loci ADIPOQ c.45 and ADIPOQ c.276 of the ADIPO gene seems to have no effect on the predisposition to AN. Girls suffering from AN with the TT genotype in loci ADIPOQ c.45 and ADIPOQ c. 276 may demonstrate higher insulin sensitivity because they have significantly higher levels of ADIPO than girls suffering from AN with other genotypes. This may be suggestive of their better adaptation to the state of malnutrition, and it has a potential effect on treatment results

Evaluation of the frequency of RETN c.62G>A and RETN c.-180C>G polymorphisms in the resistin coding gene in girls with anorexia nervosa

Introduction: Anorexia nervosa (AN) is a serious psychosomatic syndrome, classified as an eating disorder. AN patients strive to lose weight below the normal limits defined for a specific age and height, achieving their goal even at the expense of extreme emaciation. AN has a multifactorial aetiology. Genetic factors are believed to be significant in the predisposition to the development of AN. In girls suffering from AN significantly lower levels of resistin (RES) in blood serum are observed as compared to healthy girls. These differences may lead to a thesis that functional genetic polymorphisms in RES coding genes can be responsible for this phenomenon. In our pilot study we demonstrated significant differences in the distribution of genotypes in the locus RETN c.-180C>G of the RES gene in 67 girls with AN and 38 healthy girls. It seems reasonable to compare the frequency of polymorphisms of RETN c.62G>A and RETN c.-180C>G in the RES gene in girls with AN and in healthy subjects in a bigger cohort and to analyse correlations between individual variants of the polymorphisms referred to above and the RES levels in blood plasma. Material and methods: The study covered 308 girls with the restrictive form of AN (AN) and 164 healthy girls (C) (aged 11–19 years). The RES levels in blood serum were determined by means of the ELISA method on a Bio-Vendor machine from LLC (Asheville, North Carolina, USA). The DNA isolation was carried out by means of Genomic Mini AX BLOOD (SPIN). The PCR reaction was carried out on a ThermoCycle T100 thermocycler. 80–150 ng of the studied DNA and relevant F and R starters were added to the reaction mixture. The reaction products were subjected to digestion by restriction enzymes and separated on agarose gels (RFLP). Results: The average RES level in blood serum in the AN group was significantly lower (p < 0.0001) than in the C group. The distribution of genotypes in the locus RETN c.62 of the RES gene was similar in both groups. A significant difference was demonstrated in the distribution of genotypes in the polymorphic site RETN c.-180 of the RES gene between AN and C (p = 0.0145) and in the distribution of the C and G alleles in the locus RETN c.-180 (p < 0.0001). The C allele occurred significantly more frequently than the G allele in the C group as compared to the AN group. In all the study subjects jointly (AN and C) a significant positive correlation between the blood RES levels on one hand and the body mass (r = 0.42; p < 0.0001) and BMI (r = 0.61; p< 0.0001) on the other was observed. There was no correlation between the concentration of RES in blood serum and the distribution of genotypes in the loci of the resistin gene referred to above. Conclusions: The CG genotype in the locus RETN c.-180 C>G of the RES gene may constitute one of the factors predisposing to the development of AN in girls. The genotype in the loci RETN c.62 G>A and RETN c.-180 C>G of the resistin gene has no influence on the levels of this hormone in blood in AN patients

Phenotype modifiers of spinal muscular atrophy: the number of SMN2 gene copies, deletion in the NAIP gene and probably gender influence the course of the disease

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by mutations of the SMN1 gene. It is characterized by significant phenotype variability. In this study, we analyzed possible phenotype modifiers of the disease - the size of the deletion in the SMA region, the number of SMN2 gene copies, as well as the effect of gender. Among the factors analyzed, two seem to influence the SMA phenotype: the number of SMN2 gene copies and a deletion in the NAIP gene. A higher number of SMN2 copies makes the clinical symptoms more benign, and the NAIP gene deletion is associated with a more severe phenotype. The influence of gender remains unclear. In a group of 1039 patients, 55% of whom were male, the greatest disproportion was in the SMA1 (F/M = 0.78) and SMA3b (F/M = 0.45) forms. In SMA1 a deletion in the NAIP gene was seen twice as frequently in girls compared to boys. In three patients, we observed genotypes atypical for the chronic forms of SMA: two patients with SMA3a and 3b had a deletion of the NAIP gene, and a third patient with SMA2 had one copy of the SMN2 gene