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Biomedical subjects

M Carella

Publications and source records attributed to M Carella.

At least 19 recordsLinked to original sources
PubMed2006

On the statistical assessment of classifiers using DNA microarray data.

BACKGROUND: In this paper we present a method for the statistical assessment of cancer predictors which make use of gene expression profiles. The methodology is applied to a new data set of microarray gene expression data collected in Casa Sollievo della Sofferenza Hospital, Foggia--Italy. The data set is made up of normal (22) and tumor (25) specimens extracted from 25 patients affected by colon cancer. We propose to give answers to some questions which are relevant for the automatic diagnosis of cancer such as: Is the size of the available data set sufficient to build accurate classifiers? What is the statistical significance of the associated error rates? In what ways can accuracy be considered dependant on the adopted classification scheme? How many genes are correlated with the pathology and how many are sufficient for an accurate colon cancer classification? The method we propose answers these questions whilst avoiding the potential pitfalls hidden in the analysis and interpretation of microarray data. RESULTS: We estimate the generalization error, evaluated through the Leave-K-Out Cross Validation error, for three different classification schemes by varying the number of training examples and the number of the genes used. The statistical significance of the error rate is measured by using a permutation test. We provide a statistical analysis in terms of the frequencies of the genes involved in the classification. Using the whole set of genes, we found that the Weighted Voting Algorithm (WVA) classifier learns the distinction between normal and tumor specimens with 25 training examples, providing e = 21% (p = 0.045) as an error rate. This remains constant even when the number of examples increases. Moreover, Regularized Least Squares (RLS) and Support Vector Machines (SVM) classifiers can learn with only 15 training examples, with an error rate of e = 19% (p = 0.035) and e = 18% (p = 0.037) respectively. Moreover, the error rate decreases as the training set size increases, reaching its best performances with 35 training examples. In this case, RLS and SVM have error rates of e = 14% (p = 0.027) and e = 11% (p = 0.019). Concerning the number of genes, we found about 6000 genes (p < 0.05) correlated with the pathology, resulting from the signal-to-noise statistic. Moreover the performances of RLS and SVM classifiers do not change when 74% of genes is used. They progressively reduce up to e = 16% (p < 0.05) when only 2 genes are employed. The biological relevance of a set of genes determined by our statistical analysis and the major roles they play in colorectal tumorigenesis is discussed. CONCLUSIONS: The method proposed provides statistically significant answers to precise questions relevant for the diagnosis and prognosis of cancer. We found that, with as few as 15 examples, it is possible to train statistically significant classifiers for colon cancer diagnosis. As for the definition of the number of genes sufficient for a reliable classification of colon cancer, our results suggest that it depends on the accuracy required.

Aged↗
PubMed2005

Espin gene (ESPN) mutations associated with autosomal dominant hearing loss cause defects in microvillar elongation or organisation.

BACKGROUND: Espins are actin bundling proteins present in hair cell stereocilia. A recessive mutation in the espin gene (Espn) has been detected in the jerker mouse and causes deafness, vestibular dysfunction, and hair cell degeneration. More recently mutations in the human espin gene (ESPN) have been described in two families affected by autosomal recessive hearing loss and vestibular areflexia. OBJECTIVE: To report the identification of four additional ESPN mutations (S719R, D744N, R774Q, and delK848) in patients affected by autosomal dominant hearing loss without vestibular involvement. RESULTS: To determine whether the mutated ESPN alleles affected the biological activity of the corresponding espin proteins in vivo, their ability to target and elongate the parallel actin bundles of brush border microvilli was investigated in transfected LLC-PK1-CL4 epithelial cells. For three mutated alleles clear abnormalities in microvillar length or distribution were obtained. CONCLUSIONS: The results further strengthen the causative role of the espin gene in non-syndromic hearing loss and add new insights into espin structure and function.

Amino Acid Sequence↗
PubMed2004

Clinical and genetic studies in hereditary spastic paraplegia with thin corpus callosum.

BACKGROUND: A complicated form of recessive hereditary spastic paraplegias (HSPs) with thin corpus callosum (TCC) was first described in Japan, and most of the Japanese families showed linkage to chromosome 15q13-15. A recessive HSP locus (SPG11) has also been mapped to chromosome 15q13-15 in Italian and North American families with and without TCC, and it overlaps the region identified in the Japanese families. OBJECTIVE: To study clinically and genetically 12 Italian families with HSP and TCC. METHODS: The authors investigated 18 affected and 30 healthy individuals from 12 unrelated Italian families with recessive HSP-TCC. Clinical, neurophysiologic, and neuroradiologic studies were undertaken. All patients were negative for SPG7 mutations. Genetic linkage analyses were carried out with polymorphic DNA markers on 15q13-15. RESULTS: Five families were consistent with linkage, thus defining a 19.8-cM region between markers D15S1007 and D15S978, encompassing the SPG11 interval. In one consanguineous family, linkage could be firmly excluded, confirming genetic heterogeneity. Two families appeared not linked to the region, but this could not be firmly proved because of the small family size. The remaining four families were uninformative for linkage purposes. CONCLUSION: HSP-TCC is common in Italy. The phenotype is fairly homogeneous and is associated with impaired cognition. There are at least two loci for HSP-TCC, one of which is on chromosome 15q13-15.

Adolescent↗
PubMed2004

Molecular basis of hypoxanthine-guanine phosphoribosyltransferase deficiency in Italian Lesch-Nyhan patients: identification of nine novel mutations.

Lesch-Nyhan syndrome (LSN, McKusick 300322) is an X-linked genetic disease due, in its typical form, to the complete absence of hypoxanthine-guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8) enzyme activity. It is characterized by hyperuricaemia, leading to gout and kidney stones, accompanied by severe neurological dysfunction with self-injurious behaviour, choreoathetosis and spasticity. Based on a worldwide birth incidence estimate of about 1:380000, one or two new cases are expected every year in Italy. We performed biochemical and molecular genetic studies on 28 Italian patients from 25 families who are likely to represent most living individuals with the syndrome in the country. They all had absent HPRT activity and a typical LNS phenotype. Genetic analysis identified 24 HPRT mutations, 9 of which had not been previously reported: 74C>G (P25R), IVS2+1G>C, 194-195delTC, 329-332delCAAC insTCTs, IVS9-1G>A, 506insC, IVS8-1G>C, 606G>T (L202F), 418G>C (G140R). No mutation hotspots were identified. Only two mutations were found in more than one family, indicating the lack of any major mutation causing LNS in Italy. Three mutations arose de novo , two in the proband's mother, one in the maternal grandmother. The virtual complete absence of HPRT activity was related to deletions, nonsense, or missense mutations leading to nonconservative amino acid changes.

Adolescent↗
PubMed2004

[Prosthetic rehabilitation of edentulous patients after stroke].

AIM: Stroke is actually the 3rd cause of death in the world after cardiovascular diseases and cancer. In Italy, every year there are 100000 new cases; 2/3 of them die or become heavily disabled. The greatest part of patients which survive is old-aged and 70% of patients that survive is a removable denture wearer. METHODS: At the Neurological Clinic of the Polyclinic Hospital of Bari we have studied 14 removable denture wearers that had had a stroke. RESULTS: We observed that 85.7 % of removable dentures were inefficient, in 50% there will need a new removable prosthesis; 50% of persons had a bad dental hygiene; 93% of denture wearers with stroke didn't make an odontoiatric control after stroke. CONCLUSIONS: Although the analysis of the orodental status has been carried out on a limited number of patients, the need of a greater motivation and solicitation in dental check-up is underlined. The role of the dentist in oral rehabilitation and in rehabilitation of post stroke dysphagia in stroke survivors is also examined.

Aged↗
PubMed2003

Intergenerational instability and marked anticipation in SCA-17.

The authors describe an Italian family with autosomal dominant ataxia, dementia, psychiatric and extrapyramidal features, epilepsy, mild sensorimotor axonal neuropathy, and MRI findings of cerebral and cerebellar atrophy. A child had a distinctive presentation with onset at 3 years, growth retardation, fast progression, and early death. Molecular analysis demonstrated an expanded CAG/CAA repeat in the TBP gene (SCA-17). The repeat size was 66 triplets in the child and 53 in all the other patients.

Adolescent↗
PubMed2003

Dementia, ataxia, extrapyramidal features, and epilepsy: phenotype spectrum in two Italian families with spinocerebellar ataxia type 17.

We observed two families with a dominantly inherited complex neurological syndrome with onset in adulthood. Family F included 9 affected in four generations. One patient showed prominent anticipation of onset age. Onset was with cerebellar signs followed by dementia, psychiatric symptoms, seizures, and extrapyramidal features. Family M included 14 affected individuals in five generations. Presenting symptoms were either psychiatric and cognitive impairment or a cerebellar syndrome. Extrapyramidal features, dysphagia, incontinence, seizures, and myoclonus may occur. In both families magnetic resonance imaging showed marked atrophy of the brain and cerebellum. Molecular analyses demonstrated an expanded CAG/CAA repeat in the in the TATA box-binding protein (TBP) gene (SCA17).

Adolescent↗
PubMed2002

Charcot-Marie-Tooth disease type 2C: a distinct genetic entity. Clinical and molecular characterization of the first European family.

Charcot- Marie-Tooth disease type 2 is clinically and genetically heterogeneous. A particular clinical subtype of autosomal dominant Charcot-Marie-Tooth disease type 2, characterized by diaphragm and vocal cord paralysis, is labelled Charcot-Marie-Tooth disease type 2C but no genetic locus has been mapped for this form. We describe the first European family affected by Charcot-Marie-Tooth disease type 2C. Genetic analysis excluded linkage to locus of Charcot-Marie-Tooth disease type 2A, B, D, E and F, and to locus of distal hereditary motor neuronopathy type VII. In this family the disease has high penetrance, variable severity and apparently the most severe limb muscle involvement in the youngest generation. Vocal cord paralysis is unrelated to the degree of muscular weakness and patients with the most severe muscle involvement have absent or minimal respiratory symptoms. Charcot-Marie-Tooth disease type 2C is clinically and genetically different from Charcot-Marie-Tooth disease type 2A, B, D, E and F, and is not allelic with distal hereditary motor neuronopathy type VII.

Adult↗
PubMed2001

MYO6, the human homologue of the gene responsible for deafness in Snell's waltzer mice, is mutated in autosomal dominant nonsyndromic hearing loss.

Mutations in the unconventional myosin VI gene, Myo6, are associated with deafness and vestibular dysfunction in the Snell's waltzer (sv) mouse. The corresponding human gene, MYO6, is located on chromosome 6q13. We describe the mapping of a new deafness locus, DFNA22, on chromosome 6q13 in a family affected by a nonsyndromic dominant form of deafness (NSAD), and the subsequent identification of a missense mutation in the MYO6 gene in all members of the family with hearing loss.

Amino Acid Sequence↗
PubMed2001

DHPLC analysis of the MECP2 gene in Italian Rett patients.

Rett Syndrome (RTT) is an X-linked dominant neurodevelopmental disorder, which almost exclusively affects girls, with an estimated prevalence of one in 10,000-15,000 female births. Mutations in the methyl CpG binding protein 2 gene (MECP2) have been identified in roughly 75% of classical Rett girls. The vast majority of Rett cases (99%) are sporadic in origin, and are due to de novo mutations. We collected DNA samples from 50 Italian classical Rett girls, and screened the MECP2 coding region for mutations by denaturing high-performance liquid chromatography (DHPLC) and subsequent direct sequencing. DHPLC is a recently developed method for mutation screening which identifies heteroduplexes formed in DNA samples containing mismatches between wild type and mutant DNA strands, combining high sensitivity, reduced cost per run, and high throughput. In our series, 19 different de novo MECP2 mutations, eight of which were previously unreported, were found in 35 out of 50 Rett girls (70%). Seven recurrent mutations were characterized in a total of 22 unrelated cases. Initial DHPLC screening allowed the identification of 17 out of 19 different mutations (90%); after optimal conditions were established, this figure increased to 100%, with all recurrent MECP2 mutations generating a characteristic chromatographic profile. Detailed clinical data were available for 27 out of 35 mutation carrying Rett girls. Milder disease was detectable in patients carrying nonsense mutation as compared to patients carrying missense mutations, although this difference was not statistically significant (P = 0.077).

Chromatography, High Pressure Liquid↗
PubMed2001

Gastro-intestinal stromal tumor (GIST): case report.

Gastro-intestinal stromal tumors (GISTs), as currently defined, represent the largest category of primary non epithelial neoplasms of the gastrointestinal tract. They arise from mesenchymal cells located in the wall of the organ and show a remarkable variability in their differentiation pathways. For this reason there is relevant degree of confusion in their interpretation. On the basis of immunohistochemical and ultrastructural studies these neoplasms are divided into several categories: leiomyomas, schwannomas and less differentiated tumors referred as GIST. In the small bowel GIST are uncommon. Usually asymptomatic, they could be the cause of surgical emergencies like massive bleeding, obstruction, intussusception or perforation. Generally benign, an higher percentage of malignant cases are described in the small bowel. The Authors report a case of malignant GIST of the small intestine presented with bowel obstruction by ileal invagination. In this case, as usually it happens in malignant GIST, the final diagnosis was obtained by an abdominal surgical exploration.

Aged↗
PubMed2000

The gene TFR2 is mutated in a new type of haemochromatosis mapping to 7q22.

Haemochromatosis is a common recessive disorder characterized by progressive iron overload, which may lead to severe clinical complications. Most patients are homozygous for the C282Y mutation in HFE on 6p (refs 1-5). A locus for juvenile haemochromatosis (HFE2) maps to 1q (ref. 7). Here we report a new locus (HFE3) on 7q22 and show that a homozygous nonsense mutation in the gene encoding transferrin receptor-2 (TFR2) is found in people with haemochromatosis that maps to HFE3.

Animals↗
PubMed2000

Detection of C282Y and H63D in the HFE gene.

The gene for hemochromatosis was identified in 1996 and two mutations were found. Homozygosity for one of these, C282Y, is associated with hemochromatosis in a high percentage of patients. Genetic analysis of patient DNA is, therefore, a very useful tool to aid and confirm diagnosis and to screen asymptomatic relatives of patients to identify those at risk of developing this common, easily treated disease.

DNA Primers↗
PubMed2000

Geographic distribution of CDA-II: did a founder effect operate in Southern Italy?

BACKGROUND AND OBJECTIVE: Congenital dyserythropoietic anemia type II (CDA-II) is an autosomal recessive condition, whose manifestations range from mild to moderate. Its exact prevalence is unknown. Based on a recently established International Registry of CDA-II (64 unrelated kindreds), a high frequency of CDA II families living in South Italy became evident. DESIGN AND METHODS: The aim of this study was to define the haplotypes of the CDA II kindreds living in Southern Italy based on markers D20S884, D20S863, RPN, D20S841 and D20S908. These markers map to 20q11.2, within the interval of the CDAN2 gene that is responsible for CDA II. Next, we looked at these markers in kindreds from other regions of Italy and from other countries, with special attention to families having ancestors in Southern Italy. RESULTS: Evaluation of the geographic distribution of the ancestry of Italian CDA-II patients clearly demonstrated the unusually high incidence of this condition in Southern Italy. Our statistical calculations and linkage disequilibrium data also clearly demonstrate a strong association of the markers of chromosome 20 with the disease locus in our sample. Almost all the regions defined by the markers here used is in disequilibrium with the disease. Combining the data from the Italian sample together with those obtained from the non-Italian ones, we can restrict the area of highest disequilibrium to that defined by markers D20S863-D20S908. INTERPRETATION AND CONCLUSIONS: Despite the presence of this linkage disequilibrium the search for a common haplotype failed. This could suggest that the mutation was very old or that it occurred more than once on different genetic backgrounds.

Adolescent↗
PubMed1999

Familial pseudohyperkalemia maps to the same locus as dehydrated hereditary stomatocytosis (hereditary xerocytosis).

Familial pseudohyperkalemia is a "leaky red blood cell" condition in which the cells show a temperature-dependent loss of potassium (K) from red blood cells when stored at room temperature, manifesting as apparent hyperkalemia. The red blood cells show a reduced lifespan in vivo but there is no frank hemolysis. Studies of cation content and transport show a marginal increase in permeability at 37 degrees C and a degree of cellular dehydration, qualitatively similar to the changes seen in dehydrated hereditary stomatocytosis (hereditary xerocytosis). Physiological studies have shown that the passive leak to K has an abnormal temperature dependence, such that the leak is less sensitive to temperature than that in normal cells. We performed genetic mapping on the original family and found that the condition in this kindred maps to the same locus (16q23-ter) that we have previously identified for an Irish family with dehydrated hereditary stomatocytosis, which does not show the same temperature effects.

Anemia, Hemolytic, Congenital↗
PubMed1999

Juvenile hemochromatosis locus maps to chromosome 1q.

Juvenile hemochromatosis (JH) is an autosomal recessive disorder that leads to severe iron loading in the 2d to 3d decade of life. Affected members in families with JH do not show linkage to chromosome 6p and do not have mutations in the HFE gene that lead to the common hereditary hemochromatosis. In this study we performed a genomewide search to map the JH locus in nine families: six consanguineous and three with multiple affected patients. This strategy allowed us to identify the JH locus on the long arm of chromosome 1. A maximum LOD score of 5.75 at a recombination fraction of 0 was detected with marker D1S498, and a LOD score of 5. 16 at a recombination fraction of 0 was detected for marker D1S2344. Homozygosity mapping in consanguineous families defined the limits of the candidate region in an approximately 4-cM interval between markers D1S442 and D1S2347. Analysis of genes mapped in this interval excluded obvious candidates. The JH locus does not correspond to the chromosomal localization of any known gene involved in iron metabolism. These findings provide a means to recognize, at an early age, patients in affected families. They also provide a starting point for the identification of the affected gene by positional cloning.

Adolescent↗
PubMed1999

Identification of LMX1B gene point mutations in italian patients affected with Nail-Patella syndrome.

Nail-Patella syndrome, or osteo-onychodysplasia, is an autosomal dominant disorder characterized by nail dysplasia, absent or hypoplastic patellae, iliac horns and nephropathy. Previous studies have demonstrated linkage of the Nail-Patella locus with polymorphic markers on human chromosome 9q34. Recently, point mutations in the LMX1B gene have been identified in Nail-Patella patients and in families with recurrence of Nail-Patella syndrome and open-angle glaucoma. We describe here the identification of additional point mutations in the LMX1B gene in a set of Italian patients affected with Nail-Patella syndrome: two deletions of 1 and 2 bp causing a frameshift in two sporadic patients and nonsense mutations in two familial and one sporadic cases have been identified. All the mutations affect the homeodomain of the LMX1B protein and could cause the Nail-Patella syndrome through a loss of function as well as a dominant negative effect. Haplotype analysis in the two familial cases carrying the same stop codon mutation suggests the presence of a founder effect. Finally, analysis of cDNA clones obtained from human fetal kidney has revealed the existence of two different transcripts of LMX1B gene likely due to an alternative splicing.

Alternative Splicing↗