No description available.

The aim of this thesis is to summarize the available data concerning the influence of trombophilic states on the process of pregnancy and to present the results obtained by investigating the prevalence of congenital trombophilia in infertile women and its influence on the success rate of assisted reproduction. It is aimed at those interested in the problematics - be it professionals, medical students or women planning pregnancy or cannot get pregnant. The theoretical part draws data from literature written by leading Czech experts in the field and from scientific journals, included are also foreign sources. The practical part was executed with the kind permission of the PRONATAL s.r.o. centre for assisted reproduction. Key words: venous thromboembolism, trombophilia, trombophylaxis, gravidity, mutation, screening

As distrofias musculares tipo cinturas (DMC) incluem um grupo heterogêneo de doenças genéticas, caracterizadas por degeneração progressiva da musculatura esquelética pélvica e escapular, cuja herança pode ser autossômica dominante (DMC1) ou autossômica recessiva (DMC2). As formas dominantes são relativamente raras, compreendendo menos que 10% dos casos. Até o momento foram mapeados 8 locos para DMC1, (DMC1A-H), onde 3 genes já foram identificados (DMC1A-C) e 17 locos para DMC2 (DMC2A-Q), onde 16 genes já foram identificados. No presente estudo, identificamos uma família uruguaia (família 1) com 11 indivíduos afetados por DMC, distribuídos em 3 gerações, com um padrão de herança autossômico dominante. Os objetivos desse trabalho foram: mapear e refinar o loco gênico associado a uma manifestação familiar de DMC1, verificar se há co-localização da região mapeada com outras formas de DMC1 descritas na literatura e, apontar genes candidatos na região mapeada e triar mutações. Foi realizado estudo de ligação, no qual mapeou-se o loco para essa doença na região 4q13-q24 com Lod score de valor máximo 4.78 para o marcador D4S414. A região foi delimitada entre os marcadores D4S392 e D4S1572. A análise da região redefiniu o loco em 4q21.22-21.23, com uma redução de 33 Mb para 4Mb. Esse loco compreende a DMC1G (família 2), descrita anteriormente pelo nosso grupo. A triagem de mutação, realizada em amostras de afetados das duas famílias, nos permitiu encontrar uma alteração Thr141Iso no exon 5 do gene FAM175A apenas nos pacientes da família 2. Essa mesma alteração foi encontrada em 1 dos 500 controles testados, o que não nos permite excluir esse gene como um candidato para DMC1G já vez que essa frequência foi inferior a 1%. O fato dessa alteração não ter sido vista na família 1 também não nos permite excluí-lo, pois foi sequenciada apenas a região exônica e a metodologia utilizada também não nos permite verificar deleções nem duplicações. Estudos mais detalhados precisam ser realizados a fim de elucidar: (1) se a alteração desse gene é a causadora dessas DMCs ou, (2) se excluído esse gene, poderia ser o responsável. / Limb girdle muscular dystrophy (LGMD) include a heterogeneous group of genetic diseases characterized by progressive degeneration of skeletal muscles of the pelvic and scapular girdles, whose inheritance may be autosomal dominant (LGMD1) or autosomal recessive (LGMD2). The dominant forms are relatively rare, comprising less than 10% of cases. So far eight loci were mapped for LGMD1 (LGMD1A-H), where three genes have been identified (LGMD1A-C) and 17 loci for LGMD2 (LGMD2A-Q), with 16 identified genes. In this study, we analised a family from Uruguay (family 1) with 12 individuals affected by LGMD, with an autosomal dominant pattern distributed in three generations. The objectives of this study were: to map and refine the gene locus associated with a familial DMC1, check for co-location of the mapped region to other forms of DMC1 described in the literature and, to point candidate genes mapped in the region and to screen mutations. A linkage study was conducted, and we mapped the locus for this disease in the region 4q13-q24 with a maximum Lod score of 4.78 for marker D4S414. The region was defined between markers D4S392 and D4S1572. The analysis of the region has redefined the locus to 4q21.22-in 21:23, a reduction from 33 Mb to 4 Mb. This site includes LGMD1G (family 2), previously described by our group. Mutation screening, performed on samples of affected pacients from both families, allowed us to find a modification Thr141Iso in exon 5 on FAM175A gene only in patients of family 2. This same alteration was found in one of the 500 controls tested but does not allow us to exclude this gene as a candidate for LGMD1G since that frequency was less than 1%. The fact that this change was not seen in a family 1 does not allow us to exclude it either because only the exonic region was sequenced and the methodology used does not allow us to detect deletions or duplications. More detailed studies should be conducted to elucidate: (1) whether the alteration found in this gene is the cause of these DMCs, or (2) if not this gene, which could be the one responsible.

A síndrome de Treacher Collins (STC) é um distúrbio do desenvolvimento craniofacial de herança autossômica dominante causada por mutações no gene TCOF1, localizado no cromossomo 5 (5q32). Utilizando as técnicas de SSCP e seqüenciamento, estabelecemos um método eficiente para a detecção de mutações no gene TCOF1, o que permitiu oferecer o teste diagnóstico aos pacientes com suspeita clínica de STC. Identificamos a mutação responsável pela síndrome em 39/43 (90,7%) dos pacientes atendidos pelo Centro de Estudos do Genoma Humano e em 23/48 (48%) dos pacientes encaminhados pelo Johns Hopkins Medical Institute. Desse modo, caracterizamos 43 novas mutações patogênicas e 16 novos polimorfismos no gene TCOF1. A detecção de uma troca de aminoácido de caráter patogênica em uma região conservada da proteína nos levou a propor a existência de um domínio funcional importante nessa região. Realizamos triagem de mutações no gene TCOF1 em 24 pacientes com anomalias faciais em estruturas derivadas do 1o e 2o arcos branquiais, mas sem diagnóstico de STC. Nenhuma mutação patogênica foi encontrada nesses casos, indicando que a STC, apesar de apresentar uma grande variabilidade clínica, é uma entidade circunscrita. Triamos também, pela primeira vez, duas famílias cujo padrão de segregação do quadro clínico sugere um padrão de herança autossômico recessivo. Também nesse caso não encontramos mutação no gene TCOF1, apesar de uma análise de segregação com marcadores da região 5q31-q34 não ter excluído essa região de uma possível relação com a síndrome. Testamos, empregando pela primeria vez ferramentas moleculares, a hipótese que as mutações esporádicas que causam a STC têm origem preferencial na linhagem germinativa de homens mais velhos. Ao contrário do sugerido pela literatura, em dez casos informativos encontramos 70% das mutações no cromossomo herdado do pai e 30% de origem materna e nenhuma correlação com aumento de idade paterna. / Treacher Collins syndrome (TCS) is an autosomal dominant disorder affecting craniofacial development. The syndrome is caused by mutations in the TCOF1 gene, located in chromosome 5 (5q32). Combining SSCP and sequencing, we established an efficient method of screening for mutations in the TCOF1 gene, allowing us to offer diagnostic tests to patients with clinical signs of TCS. We detected a pathogenic mutation in 39/43 (90.7%) of patients ascertained at the Centro de Estudos do Genoma Humano and in 23/48 (48%) of patients referred to Johns Hopkins Medical Institute. We therefore characterized 43 novel pathogenic mutations and 16 novel polymorphisms in the TCOF1 gene. We described a pathogenic missense mutation located in a conserved region of the protein, which led us to propose the existence of a critical function domain in its N-terminus. After screening 24 patients with craniofacial anomalies resembling TCS but without a precise clinical diagnosis for mutations in the TCOF1 gene, we found no pathogenic mutation and concluded that, despite its broad clinical spectrum, TCS is well characterized in clinical grounds. We also screened, for the first time, two families in which the segregation of the phenotype suggested autosomal recessive inheritance. No mutation was detected in these families, despite linkage analysis with markers from 5q31-34 not excluding this region. We used molecular techniques for the first time to test the hypothesis that sporadic mutations in TCS arise preferentially in the male germ line and their frequency increases with age. As opposed to what the literature suggested, in ten informative cases we had 7 mutations of paternal origin and 3 originating in the female germ line, with no detectable age effect.

Thesis (MSc (Genetics))--University of Stellenbosch, 2008. / The porphyrias are a group of genetic diseases resulting from the accumulation of haem precursors due to defective enzyme activity in either one of the last seven enzymes in the haem biosynthesis pathway. One of the common hepatic porphyrias, porphyria cutanea tarda (PCT), arises from the inhibition of uroporphyrinogen decarboxylase (UROD) activity. It is characterised by excessive urinary and hepatic excretion of uroporphyrinogens and manifests cutaneously in the form of dermatitis. Two main forms of PCT have been described, namely familial PCT (fPCT) and sporadic PCT (sPCT). PCT is a complex disease and a few genetic (including modifier loci) and environmental precipitating factors have been implicated in the aetiology of PCT. An important exacerbating factor, iron overload, is observed in the majority of PCT patients. The aim of this study was to determine whether DNA sequence variation in the 5' untranslated regulatory region of four genes involved in iron metabolism i.e. CP, CYBRD1, HAMP and SLC40A1 may in any way be associated with PCT. The study cohort consisted of 74 patients from three diverse South African populations including 15 Black (eight males and seven females), 30 Caucasian (13 male and 17 females) and 29 Coloured (18 males and 11 females) individuals as well as 132 population-matched controls. The promoter region of the selected genes were screened for variation utilising the techniques of polymerase chain reaction (PCR) amplification, heteroduplex single-stranded conformational polymorphism (HEX-SCCP) analysis, restriction fragment length polymorphism (RFLP) analysis and bi-directional semi-automated DNA sequencing. Twenty three previously described and eleven novel variants were identified. The novel variants comprised CYBRD1: -1540G/A, -1474G/A, -1452T/C, -1346T/C, -1272T/C, -645T/C; G(T)8G(T)nG(T)nG(T)9; HAMP: -429G/T and SLC40A1: -1461T/C, -1399G/A, -524C/T. Statistically significant associations were observed at a number of loci. In silico analysis revealed several putative transcription factor binding sites (TFBSs) spanning the regions of variation. The disruption of an existing (or creation of a novel) TFBS is thought to occur in the presence of a variant in a number of instances. This may lead to the manipulation of transcription rates, thereby depicting a possible mechanism for gene dysregulation. The study presented here was undertaken as a preliminary investigation to determine the contribution (if any) of variants in the regulatory regions of candidate genes in iron metabolism in South African PCT patients. Considering the increasing incidence of PCT, in particular the Black South African population, it is necessary to elucidate the underlying mechanisms of iron overload in PCT patients. The propitious findings signified in the study, in conjunction with phenotypegenotype correlations, will assist in clarifying the association between iron overload and PCT. / jfl2010 / Imported from http://etd.sun.ac.za April 2010.

As distrofias musculares tipo cinturas (DMC) incluem um grupo heterogêneo de doenças genéticas, caracterizadas por degeneração progressiva da musculatura esquelética pélvica e escapular, cuja herança pode ser autossômica dominante (DMC1) ou autossômica recessiva (DMC2). As formas dominantes são relativamente raras, compreendendo menos que 10% dos casos. Até o momento foram mapeados 8 locos para DMC1, (DMC1A-H), onde 3 genes já foram identificados (DMC1A-C) e 17 locos para DMC2 (DMC2A-Q), onde 16 genes já foram identificados. No presente estudo, identificamos uma família uruguaia (família 1) com 11 indivíduos afetados por DMC, distribuídos em 3 gerações, com um padrão de herança autossômico dominante. Os objetivos desse trabalho foram: mapear e refinar o loco gênico associado a uma manifestação familiar de DMC1, verificar se há co-localização da região mapeada com outras formas de DMC1 descritas na literatura e, apontar genes candidatos na região mapeada e triar mutações. Foi realizado estudo de ligação, no qual mapeou-se o loco para essa doença na região 4q13-q24 com Lod score de valor máximo 4.78 para o marcador D4S414. A região foi delimitada entre os marcadores D4S392 e D4S1572. A análise da região redefiniu o loco em 4q21.22-21.23, com uma redução de 33 Mb para 4Mb. Esse loco compreende a DMC1G (família 2), descrita anteriormente pelo nosso grupo. A triagem de mutação, realizada em amostras de afetados das duas famílias, nos permitiu encontrar uma alteração Thr141Iso no exon 5 do gene FAM175A apenas nos pacientes da família 2. Essa mesma alteração foi encontrada em 1 dos 500 controles testados, o que não nos permite excluir esse gene como um candidato para DMC1G já vez que essa frequência foi inferior a 1%. O fato dessa alteração não ter sido vista na família 1 também não nos permite excluí-lo, pois foi sequenciada apenas a região exônica e a metodologia utilizada também não nos permite verificar deleções nem duplicações. Estudos mais detalhados precisam ser realizados a fim de elucidar: (1) se a alteração desse gene é a causadora dessas DMCs ou, (2) se excluído esse gene, poderia ser o responsável. / Limb girdle muscular dystrophy (LGMD) include a heterogeneous group of genetic diseases characterized by progressive degeneration of skeletal muscles of the pelvic and scapular girdles, whose inheritance may be autosomal dominant (LGMD1) or autosomal recessive (LGMD2). The dominant forms are relatively rare, comprising less than 10% of cases. So far eight loci were mapped for LGMD1 (LGMD1A-H), where three genes have been identified (LGMD1A-C) and 17 loci for LGMD2 (LGMD2A-Q), with 16 identified genes. In this study, we analised a family from Uruguay (family 1) with 12 individuals affected by LGMD, with an autosomal dominant pattern distributed in three generations. The objectives of this study were: to map and refine the gene locus associated with a familial DMC1, check for co-location of the mapped region to other forms of DMC1 described in the literature and, to point candidate genes mapped in the region and to screen mutations. A linkage study was conducted, and we mapped the locus for this disease in the region 4q13-q24 with a maximum Lod score of 4.78 for marker D4S414. The region was defined between markers D4S392 and D4S1572. The analysis of the region has redefined the locus to 4q21.22-in 21:23, a reduction from 33 Mb to 4 Mb. This site includes LGMD1G (family 2), previously described by our group. Mutation screening, performed on samples of affected pacients from both families, allowed us to find a modification Thr141Iso in exon 5 on FAM175A gene only in patients of family 2. This same alteration was found in one of the 500 controls tested but does not allow us to exclude this gene as a candidate for LGMD1G since that frequency was less than 1%. The fact that this change was not seen in a family 1 does not allow us to exclude it either because only the exonic region was sequenced and the methodology used does not allow us to detect deletions or duplications. More detailed studies should be conducted to elucidate: (1) whether the alteration found in this gene is the cause of these DMCs, or (2) if not this gene, which could be the one responsible.

A síndrome de Treacher Collins (STC) é um distúrbio do desenvolvimento craniofacial de herança autossômica dominante causada por mutações no gene TCOF1, localizado no cromossomo 5 (5q32). Utilizando as técnicas de SSCP e seqüenciamento, estabelecemos um método eficiente para a detecção de mutações no gene TCOF1, o que permitiu oferecer o teste diagnóstico aos pacientes com suspeita clínica de STC. Identificamos a mutação responsável pela síndrome em 39/43 (90,7%) dos pacientes atendidos pelo Centro de Estudos do Genoma Humano e em 23/48 (48%) dos pacientes encaminhados pelo Johns Hopkins Medical Institute. Desse modo, caracterizamos 43 novas mutações patogênicas e 16 novos polimorfismos no gene TCOF1. A detecção de uma troca de aminoácido de caráter patogênica em uma região conservada da proteína nos levou a propor a existência de um domínio funcional importante nessa região. Realizamos triagem de mutações no gene TCOF1 em 24 pacientes com anomalias faciais em estruturas derivadas do 1o e 2o arcos branquiais, mas sem diagnóstico de STC. Nenhuma mutação patogênica foi encontrada nesses casos, indicando que a STC, apesar de apresentar uma grande variabilidade clínica, é uma entidade circunscrita. Triamos também, pela primeira vez, duas famílias cujo padrão de segregação do quadro clínico sugere um padrão de herança autossômico recessivo. Também nesse caso não encontramos mutação no gene TCOF1, apesar de uma análise de segregação com marcadores da região 5q31-q34 não ter excluído essa região de uma possível relação com a síndrome. Testamos, empregando pela primeria vez ferramentas moleculares, a hipótese que as mutações esporádicas que causam a STC têm origem preferencial na linhagem germinativa de homens mais velhos. Ao contrário do sugerido pela literatura, em dez casos informativos encontramos 70% das mutações no cromossomo herdado do pai e 30% de origem materna e nenhuma correlação com aumento de idade paterna. / Treacher Collins syndrome (TCS) is an autosomal dominant disorder affecting craniofacial development. The syndrome is caused by mutations in the TCOF1 gene, located in chromosome 5 (5q32). Combining SSCP and sequencing, we established an efficient method of screening for mutations in the TCOF1 gene, allowing us to offer diagnostic tests to patients with clinical signs of TCS. We detected a pathogenic mutation in 39/43 (90.7%) of patients ascertained at the Centro de Estudos do Genoma Humano and in 23/48 (48%) of patients referred to Johns Hopkins Medical Institute. We therefore characterized 43 novel pathogenic mutations and 16 novel polymorphisms in the TCOF1 gene. We described a pathogenic missense mutation located in a conserved region of the protein, which led us to propose the existence of a critical function domain in its N-terminus. After screening 24 patients with craniofacial anomalies resembling TCS but without a precise clinical diagnosis for mutations in the TCOF1 gene, we found no pathogenic mutation and concluded that, despite its broad clinical spectrum, TCS is well characterized in clinical grounds. We also screened, for the first time, two families in which the segregation of the phenotype suggested autosomal recessive inheritance. No mutation was detected in these families, despite linkage analysis with markers from 5q31-34 not excluding this region. We used molecular techniques for the first time to test the hypothesis that sporadic mutations in TCS arise preferentially in the male germ line and their frequency increases with age. As opposed to what the literature suggested, in ten informative cases we had 7 mutations of paternal origin and 3 originating in the female germ line, with no detectable age effect.

X-linked myopathy with excessive autophagy (XMEA) is a skeletal muscle disorder inherited in recessive fashion, affecting boys and sparing carrier females. Onset is in childhood with weakness of the proximal muscles of the lower extremities, progressing slowly to involve other muscle groups. Pathological analysis of skeletal muscle biopsies shows no inflammation, necrosis or apoptosis. Instead, forty to 80% of fibers exhibit giant autophagic vacuoles with heterogeneous degradative content. Numerous critical functions of all cells are compartmentalized in particular pH environments established by the intracellular transmembrane V-ATPase proton pump complex. Assembly of this complex, directed by the Vma21p chaperone, is well-studied in yeast but completely unknown in other organisms. The aim of my project was a better understanding of XMEA pathogenesis, with a focus on finding the disease-causing gene. In this thesis, I identify mutations in XMEA patients in a novel, previously uncharacterized gene, which we name VMA21. Most of the mutations are located in splicing-relevant positions and decrease splicing efficiency. After establishing that XMEA is caused by hypomorphic alleles of the VMA21 gene, I show that VMA21 is the diverged human orthologue of the yeast Vma21p protein, and that like Vma21p, it is an essential assembly chaperone of the V-ATPase. Decreased VMA21 reduces V-ATPase activity, resulting in altered lysosomal pH and a blockage at the degradative step of autophagy. Towards understanding disease pathogenesis, I show evidence of compensatory autophagy upregulation consecutive to the impaired clearance. Accumulated autolysosomes due to increased autophagy continue to face the degradative block and are slow to disappear. Instead, they merge to each other and form the characteristic giant XMEA vacuoles. These results uncover a novel mechanism of disease, namely macroautophagic overcompensation leading to cell vacuolation and tissue atrophy. This work describes the clinical outcome at the cusp of tolerable reduction in V-ATPase, with implications on common diseases like osteoporosis and cancer metastasis, where increased V-ATPase activity is an important component. Our XMEA patients show that the safety margin of reducing V-ATPase activity in humans is wide, increasing the potential to utilize chemical or biological V-ATPase inhibitors as possible therapies.

<p>BACKGROUND: Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by mutations in the gene coding for microsomal triglyceride transfer protein (MTTP).</p><p>AIM: To characterize the genetic basis of ABL in two unrelated patients.</p><p>RESULTS: In the first patient, the substitution c.1911C>T in exon 12 of the <em>MTTP</em> gene, resulting in the protein substitution p.P552L, was discovered using mutation screening. The parents are heterozygous and the proband is a homozygous carrier of this substitution. Using restriction fragment length polymorphism (RFLP), 100 control subjects were analyzed and none carried the substitution indicating that it is a novel <em>MTTP </em>mutation. Sequencing of the other ABL patient showed that the proband carried a homozygous single base insertion, at position  c.2342IVS16+2-3insT, located at the donor splice-site of intron 16 resulting in skipping of exon 16 and truncation of the protein. The proband's mother is heterozygous for the insertion while the father does not carry the insertion. Multiplex ligation-dependent probe amplification (MLPA) did not identify any deletion encompassing exon 16 in the proband, father or mother. Nonpaternity was excluded using polymorphic markers from several chromosomes. Haplotype analysis using markers spanning chromosome 4 revealed  heterodisomy (two homologous chromosomes) of 4p and the distal part of 4q, and isodisomy (duplication of one chromosome) of 4q12-4q26.</p><p>CONCLUSION: These data show that the cause of ABL in one of the patients is a missense mutation, p.P552L, while the cause of ABL in the other patient is due to uniparental disomy, probably resulting from non-disjunstion in meiosis I.</p>

BACKGROUND: Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by mutations in the gene coding for microsomal triglyceride transfer protein (MTTP). AIM: To characterize the genetic basis of ABL in two unrelated patients. RESULTS: In the first patient, the substitution c.1911C&gt;T in exon 12 of the MTTP gene, resulting in the protein substitution p.P552L, was discovered using mutation screening. The parents are heterozygous and the proband is a homozygous carrier of this substitution. Using restriction fragment length polymorphism (RFLP), 100 control subjects were analyzed and none carried the substitution indicating that it is a novel MTTP mutation. Sequencing of the other ABL patient showed that the proband carried a homozygous single base insertion, at position  c.2342IVS16+2-3insT, located at the donor splice-site of intron 16 resulting in skipping of exon 16 and truncation of the protein. The proband's mother is heterozygous for the insertion while the father does not carry the insertion. Multiplex ligation-dependent probe amplification (MLPA) did not identify any deletion encompassing exon 16 in the proband, father or mother. Nonpaternity was excluded using polymorphic markers from several chromosomes. Haplotype analysis using markers spanning chromosome 4 revealed  heterodisomy (two homologous chromosomes) of 4p and the distal part of 4q, and isodisomy (duplication of one chromosome) of 4q12-4q26. CONCLUSION: These data show that the cause of ABL in one of the patients is a missense mutation, p.P552L, while the cause of ABL in the other patient is due to uniparental disomy, probably resulting from non-disjunstion in meiosis I.