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Guglielmina Pepe

Publications and source records attributed to Guglielmina Pepe.

At least 19 recordsLinked to original sources
PubMed2007

Diversity of cystathionine beta-synthase haplotypes bearing the most common homocystinuria mutation c.833T>C: a possible role for gene conversion.

Homozygosity or compound heterozygosity for the c.833T>C transition (p.I278 T) in the cystathionine beta-synthase (CBS) gene represents the most common cause of pyridoxine-responsive homocystinuria in Western Eurasians. However, the frequency of the pathogenic c.833C allele, as observed in healthy newborns from several European countries (q(c.833C) approximately equals 3.3 x 10(-3)), is approximately 20-fold higher than expected on the basis of the observed number of symptomatic homocystinuria patients carrying this mutation (q(c.833C) approximately equals 0.18 x 10(-3)), implying clinical underascertainment. Intriguingly, the c.833C mutation is also present in combination with a 68-bp insertion, c.[833C; 844_845ins68], in a substantial proportion of chromosomes from nonhomocystinuric individuals worldwide. We have sought to study the relationship between the pathogenic and nonpathogenic c.833C-bearing chromosomes and to determine whether the pathogenic c.[833C; -] chromosomes are identical-by-descent or instead arose by recurrent mutation. Initial haplotype analysis of 780 randomly selected Czech and sub-Saharan African wild-type chromosomes, employing 12 intragenic markers, revealed 29 distinct CBS haplotypes, of which 10 carried the c.[833C; 844_845ins68] combination; none carried an isolated c.833C or c.844_845ins68 mutation. Subsequent examination of 69 pathogenic c.[833C; -] chromosomes, derived from homocystinuria patients of predominantly European origin, disclosed three unrelated haplotypes that differed from their wild-type counterparts by virtue of the presence of c.833C, thereby indicating that c.833T>C transition has occurred repeatedly and independently in the past. Since c.833T does not reside within an obvious mutational hotspot, we surmise that the three pathogenic and comparatively prevalent c.[833C; -] chromosomes may have originated by recurrent gene conversion employing the common nonpathogenic c.[833C; 844_845ins68] chromosomes as templates.

Africa↗
PubMed2006

COL6A1 genomic deletions in Bethlem myopathy and Ullrich muscular dystrophy.

We have identified highly similar heterozygous COL6A1 genomic deletions, spanning from intron 8 to exon 13 or intron 13, in two patients with Ullrich congenital muscular dystrophy and the milder Bethlem myopathy. The 5' breakpoints of both deletions are located within a minisatellite in intron 8. The mutations cause in-frame deletions of 66 and 84 amino acids in the amino terminus of the triple-helical domain, leading to intracellular accumulation of mutant polypeptides and reduced extracellular collagen VI microfibrils. Our studies identify a deletion-prone region in COL6A1 and suggest that similar mutations can lead to congenital muscle disorders of different clinical severity.

Adult↗
PubMed2005

A homozygous COL6A2 intron mutation causes in-frame triple-helical deletion and nonsense-mediated mRNA decay in a patient with Ullrich congenital muscular dystrophy.

Ullrich congenital muscular dystrophy (UCMD) is a severe disorder caused, in most cases, by a deficiency in collagen VI microfibrils. Recessive mutations in two of the three collagen VI genes, COL6A2 and COL6A3, have been identified in eight of the nine UCMD patients reported thus far. A heterozygous COL6A1 gene deletion, resulting in a mutant protein that exerts a dominant negative effect, has recently been described in a severely affected UCMD patient. Here we describe a patient in whom reverse transcription-PCR analysis of fibroblast RNA suggested a heterozygous in-frame deletion of exon 13 in the triple-helical domain of COL6A2, which is predicted to be dominantly acting. However, a homozygous A --> G mutation at -10 of intron 12 was found in the genomic DNA. The intron mutation activated numerous cryptic splice acceptor sites, generating normal and exon 13-deleted COL6A2 mRNA, and multiple aberrant transcripts containing frameshifts that were degraded through a nonsense-mediated decay mechanism. Northern analysis indicated diminished COL6A2 mRNA expression as the primary pathogenic mechanism in this UCMD patient. Our results underscore the importance of multifaceted analyses in the accurate molecular diagnosis and interpretation of genotype-phenotype correlations of UCMD.

Base Sequence↗
PubMed2005

Dominant and recessive COL6A1 mutations in Ullrich scleroatonic muscular dystrophy.

In this study, we characterized five Ullrich scleroatonic muscular dystrophy patients (two Italians, one Belgian, and two Turks) with a clinical phenotype showing different degrees of severity, all carrying mutations localized in COL6A1. We sequenced the three entire COL6 complementary DNA. Three of five patients have recessive mutations: two patients (P1and P3) have homozygous single-nucleotide deletions, one in exon 9 and one in exon 22; one patient (P2) has a homozygous single-nucleotide substitution leading to a premature termination codon in exon 31. The nonsense mutation of P2 also causes a partial skipping of exon 31 with the formation of a premature termination codon in exon 32 in 15% of the total COL6A1 messenger RNA. The remaining two patients carry a heterozygous glycine substitution in exons 9 and 10 inside the triple-helix region; both are dominant mutations because the missense mutations are absent in the DNA of their respective parents. As for the three homozygous recessive mutations, the apparently healthy consanguineous parents all carry a heterozygous mutated allele. Here, for the first time, we report a genotype-phenotype correlation demonstrating that heterozygous glycine substitutions in the triple-helix domain of COL6A1 are dominant and responsible for a milder Ullrich scleroatonic muscular dystrophy phenotype, and that recessive mutations in COL6A1 correlate with more severe clinical and biochemical Ullrich scleroatonic muscular dystrophy phenotypes.

Adolescent↗
PubMed2005

Altered expression of the MCSP/NG2 chondroitin sulfate proteoglycan in collagen VI deficiency.

NG2, the rat homologue of the human melanoma chondroitin sulfate proteoglycan (MCSP), is a ligand for collagen VI (COL6). We have examined skeletal muscles of patients affected by Ullrich scleroatonic muscular dystrophy (UCMD), an inherited syndrome caused by COL6 genes mutations. A significant decrease of NG2 immunolabeling was found in UCMD myofibers, as well as in skeletal muscle and cornea of COL6 null-mice. In UCMD muscles, truncated NG2 core protein isoforms were detected. However, real-time RT-PCR analysis revealed marked increase in NG2 mRNA content in UCMD muscle compared to controls. We hypothesize that NG2 immunohistochemical and biochemical behavior may be compromised owing to the absence of its physiological ligand. MCSP/NG2 proteoglycan may be considered an important receptor mediating COL6-sarcolemma interactions, a relationship that is disrupted by the pathogenesis of UCMD muscle.

Animals↗
PubMed2005

Muscle MRI in Ullrich congenital muscular dystrophy and Bethlem myopathy.

The aim of this study was to evaluate the spectrum of muscle involvement on Magnetic Resonance Imaging (MRI) in patients with collagen VI related disorders. Nineteen patients with genetically confirmed collagen VI related disorders, 10 with Bethlem myopathy and 9 with Ullrich congenital muscular dystrophy (CMD), had muscle MRI of their legs using T1 sequences through calves and thighs. In patients with Bethlem myopathy the vasti muscles appeared to be the most frequently and most strikingly affected thigh muscles, with a rim of abnormal signal at the periphery of each muscle and relative sparing of the central part. Another frequent finding was the presence of a peculiar involvement of the rectus femoris with a central area of abnormal signal within the muscle. Patients with Ullrich CMD had a more diffuse involvement of the thigh muscles with relative sparing of sartorius, gracilis and adductor longus. In 8 of the 9 patients with Ullrich CMD, we also observed the peripheral rim of the vastus lateralis and the central area in the rectus femoris observed in patients with Bethlem myopathy. At calf level the results were more variable but a significant proportion of patients with both Bethlem myopathy (8/10) and Ullrich CMD (6/9) showed a rim of abnormal signal at the periphery of soleus and gastrocnemii. Bethlem myopathy and Ullrich CMD patients have distinct patterns of muscle involvement on MRI with some overlap between the two forms. Our results suggest that muscle MR may be used, as an additional tool, to identify patients with collagen VI related disorders. This information is even more important in the patients with a typical Ullrich CMD clinical phenotype but with normal collagen expression of VI in muscle and/or skin.

Adolescent↗
PubMed2005

Restriction fragment length polymorphisms of type I collagen locus 2 (COL1A2) in two communities of African ancestry and other mixed populations of northwestern Ecuador.

Restriction fragment length polymorphisms are good anthropological markers for discriminating geographically distinct populations at both the allele and the haplotype level. Two communities of African ancestry and ladinos, mestizos, and mulattoes living in the Esmeraldas province in northwestern Ecuador were analyzed for three RFLPs (EcoRI, RsaI, and MspI) of the COL1A2 gene. Also, the same markers were studied in a population sample from Spain to compare the allele and haplotype frequencies of the Esmeraldas populations with those of their representative European parental population. Data for the native American and sub-Saharan African founder components were available from the literature. No significant levels of differentiation between the two African Ecuadoran communities emerged from either the frequency analysis of each single marker and all three RFLP markers together or from the AMOVA. The ladinos and mestizos also showed a rather similar distribution of allele and haplotype frequencies, confirming that the two ethnic terms do not correspond to genetically different populations. The comparison with the supposed founding European, sub-Saharan African, and native American populations indicated a large presence of African genes in the gene pool of both communities, with a higher proportion of the Amerindian component in Viche than in Rio Cayapas. The present findings confirm the previous genetic admixture estimates based on nuclear and mitochondrial DNA markers and the demographic data.

Alleles↗
PubMed2004

[Prevalence of cardiovascular manifestations in Marfan syndrome].

BACKGROUND: Marfan syndrome is an inherited connective tissue disorder with an autosomic dominant transmission. The prevalence is 1:5000-10 000 and the clinical major criteria involve the skeletal and ocular apparatus and the cardiovascular and central nervous system. The main cause of morbidity is represented by the thoracic aortic dissection/aneurysm that is responsible for 80% of the deaths. METHODS: We performed a clinical study on 227 patients enrolled at our Clinical and Research Marfan and Related Disorders Center. The aim of this study was to describe the prevalence of cardiovascular manifestation in this cohort of patients. RESULTS: Aortic dilation was present in 172 patients (75.8%), mitral valve prolapse in 179 (78.9%). Aortic insufficiency was present in 83 patients (36.6%), mitral insufficiency in 165 (72.7%). When analyzed separately, in < 10-year and > 40-year patients aortic dilation was more prevalent than mitral valve prolapse. Three patients presented with interatrial septal defect, 4 aortic bicuspid valve; 23 had a history of ventricular and supraventricular arrhythmias, and in 2 patients an implantable cardioverter device had been implanted. Fifty-seven patients were treated with beta-blockers and 28 had been operated for aortic aneurysmal dilation. CONCLUSIONS: In Marfan syndrome mitral valve prolapse and aortic dilation are the main cardiovascular manifestations, interatrial septal defect and aortic bicuspid valve had the same prevalence than in subjects without Marfan syndrome. These data refer to our first patient evaluation; further studies are needed to evaluate the progression and the natural history of cardiovascular manifestations in Marfan syndrome.

Adult↗
PubMed2003

Phenotypic variability of cardiovascular manifestations in Marfan Syndrome. Possible role of hyperhomocysteinemia and C677T MTHFR gene polymorphism.

AIMS: The aim of this study was to evaluate (1) homocysteinemia and the prevalence of the C677T MTHFR polymorphism in Marfan patients and (2) whether the severity of cardiovascular manifestations is associated with homocysteinemia and/or C677T polymorphism. METHODS AND RESULTS: We studied 107 patients subdivided into three subgroups based on the severity of cardiovascular manifestations: (A) no involvement (n=4); (B) mild involvement (n=45); (C) aortic dilatation or aortic dissection (n=58), and 189 controls. Total homocysteine (tHcy) was significantly higher in subgroup C than in subgroup B. In subgroup C patients with dissection tHcy was higher than in those without dissection. In subgroup C the prevalence of 677T homozygotes was higher, but not significantly, than in the subgroup B. In patients with dissection the prevalence of 677T homozygotes was significantly higher than in those without dissection and than in subgroup B. In the logistic regression analysis, severe cardiovascular manifestations and aortic dissection in Marfan patients were associated with tHcy plasma levels. CONCLUSIONS: Our data indicate an association between the severity of the cardiovascular manifestations, in particular aortic dissection, and elevated tHcy levels. This suggests an important role for tHcy in determining phenotypic variability in Marfan patients and provides further evidence for the association of homocysteinemia with the damage of the vascular system.

Adolescent↗
PubMed2003

Mutational spectrum of the CTNS gene in Italy.

Classic nephropathic or infantile cystinosis (NC) is an autosomal recessive disorder; the gene coding for the integral membrane protein cystinosin, which is responsible for membrane transport of cystine (CTNS), was cloned. Mutation analysis of the CTNS gene of Caucasian patients revealed a common 57-kb deletion, and several other mutations spread throughout the entire gene. In the present study, we report the CTNS mutations identified in 42 of 46 Italian families with NC. The percentage of mutations characterized in this study is 86%. The mutational spectrum of the Italian population is different from that of populations of North European origin: the 57-kb deletion is present in a lower percentage, while the splicing mutations represent 30% of mutation detected in our sample. In all, six novel mutations have been identified, and the origin of one recurrent mutation has been traced.

Adolescent↗
PubMed2002

Effects on collagen VI mRNA stability and microfibrillar assembly of three COL6A2 mutations in two families with Ullrich congenital muscular dystrophy.

We recently reported a severe deficiency in collagen type VI, resulting from recessive mutations of the COL6A2 gene, in patients with Ullrich congenital muscular dystrophy. Their parents, who are all carriers of one mutant allele, are unaffected, although heterozygous mutations in collagen VI caused Bethlem myopathy. Here we investigated the consequences of three COL6A2 mutations in fibroblasts from patients and their parents in two Ullrich families. All three mutations lead to nonsense-mediated mRNA decay. However, very low levels of undegraded mutant mRNA remained in patient B with compound heterozygous mutations at the distal part of the triple-helical domain, resulting in deposition of abnormal microfibrils that cannot form extensive networks. This observation suggests that the C-terminal globular domain is not essential for triple-helix formation but is critical for microfibrillar assembly. In all parents, the COL6A2 mRNA levels are reduced to 57-73% of the control, but long term collagen VI matrix depositions are comparable with that of the control. The almost complete absence of abnormal protein and near-normal accumulation of microfibrils in the parents may account for their lack of myopathic symptoms.

Alleles↗
PubMed2002

Plasma and serum levels of D-dimer and their correlations with other hemostatic parameters in pregnancy.

The measurement of D-dimer in serum samples (s-DD) after standardized coagulation has been reported as a possible single global test for fibrinolysis in unstimulated conditions in healthy subjects and in patients with ischemic heart disease and with different metabolic disorders. No study has been performed on the use of this test in pregnancy, a condition characterized by physiological changes both in coagulation and in fibrinolysis. In this preliminary study, we have evaluated in 28 women with physiological pregnancy and in 23 comparable controls s-DD and a number of markers of coagulation and fibrinolysis. In nonpregnant women s-DD showed a good correlation with fibrinolytic parameters [euglobulin lysis time (ELT) and type 1 inhibitor of tissue plasminogen activator (PAI-1) act: P<.01; tissue plasminogen activator (t-PA) ag and PAI-1 ag: P<.05], confirming previous data, whereas in pregnant women no correlation was observed. Plasma DD (pls-DD) and s-DD levels were not correlated either in pregnant or in control women. s-DD levels were significantly higher than pls-DD in controls and in 15/28 pregnant women whose pls-DD values were in normal range or mildly increased (<110 ng/ml; P<.05), whereas in the 13 pregnant women with high pls-DD levels no significant differences were found between pls-DD and s-DD levels. Because in pregnancy high pls-DD levels are frequently found, possibly only as a consequence of enhanced clotting activation and fibrin deposition, we cannot exclude that D-dimer measured in serum reflects, at least in part, cross-linked fibrin degradation products (FDP) already present in blood before standardized coagulation. Therefore, D-dimer generated in vitro would account only in part for s-DD measured. This can explain why in pregnant women, differently from controls, s-DD does not correlate with fibrinolytic parameters. In conclusion, this preliminary study indicates that baseline pls-DD levels may be an important potential confounder in the interpretation of s-DD results in pregnant women and that s-DD cannot be proposed as a tool for a rapid evaluation of fibrinolytic activity in pregnancy.

Adult↗
PubMed2002

Diastolic subclinical primary alterations in Marfan syndrome and Marfan-related disorders.

BACKGROUND: The extracellular matrix tissue of the myocardium importantly contributes to left ventricular (LV) performance. Inherited connective tissue disorders related to the FBN1 gene could involve cardiac interstitium resulting in functional abnormalities. HYPOTHESIS: To disclose a primary involvement of myocardium, LV function was studied in 28 patients affected by Marfan syndrome or Marfan-related disorders: 20 Marfan and 8 MASS (Mitral valve prolapse, Myopia, Aortic dilatation, Skeletal involvement, Skin striae) and in 28 healthy, age and gender-matched controls. No valvular regurgitation or any other cardiac alterations were present. METHODS: Echocardiographic study was performed to investigate LV systolic and diastolic function. RESULTS: No statistically significant differences were observed between patients and the control group in LV dimensions, systolic function parameters (ejection and shortening fraction), and some diastolic function parameters (E peak, A peak, E/A), while statistically significant differences were found between patients and the control group in LV mass (128.7 +/- 46.6 vs. 83.7 +/- 14.5 g/m2, p<0.008), in isovolumic relaxation time (102.0 +/- 24.0 vs. 80.1 +/- 11.2 ms, p<0.016), and in deceleration time of the E wave (127.5 +/- 19.3 vs. 208.6 +/- 24.5 ms, p<0.001) and the A wave (66.4 +/- 8.2 vs. 87.5 +/- 23.4 ms, p <0.008). CONCLUSIONS: These data show an unusual pattern of transmitral diastolic flow in which a decreased ventricular compliance and reduced myocardial relaxation coexist. Thus, in Marfan syndrome and in Marfan-related disorders, subclinical diastolic alterations are present independent of valvular disease and might represent an early marker of primary myocardial involvement.

Adult↗
PubMed2002

Novel COL6A1 splicing mutation in a family affected by mild Bethlem myopathy.

Bethlem myopathy is an early-onset benign myopathy characterized by proximal muscular weakness and multiple flexion contractures. It is a dominantly inherited disorder associated with mutations in the three COL6 genes encoding type VI collagen. We detected a g-->a substitution at +1 position of COL6A1 intron 3 in a four-generation Italian family affected by a mild form of Bethlem myopathy. The mutation results in the activation of a cryptic splice donor site at the 3' end of exon 3, leading to the loss of 66 nucleotides and an "in-frame" deletion of 22 amino acids in the NH2-domain. Molecular analysis on fibroblasts of the propositus showed that the mutated mRNA was present and stable, but the mutated protein could not be detected. Western blot and immunofluorescence analyses showed a decreased level of collagen VI synthesis and deposition in fibroblasts of the propositus. Together, the results suggest that the mutated protein was highly unstable and rapidly degraded, and that the mild phenotype was caused by a reduced amount of normal collagen VI microfibrils. In addition, we demonstrated that lymphocytes can be used for the first mutation screening analysis of patients with Bethlem myopathy.

Adolescent↗