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M Frontali

Publications and source records attributed to M Frontali.

At least 37 records · Page 2Linked to original sources
PubMed1997

Acetazolamide-responsive episodic ataxia in an Italian family refines gene mapping on chromosome 19p13.

Episodic ataxia type 2 is an autosomal dominant disorder with attacks of vertigo and ataxia which respond to acetazolamide treatment. The gene, distinct from the KCNA1 responsible for episodic ataxia type 1, has been mapped on chromosome 19p13 in a 11-12 cM region. A large Italian kindred affected with acetazolamide-responsive episodic ataxia is reported, with onset in adulthood, a strong vestibular component during attacks and a high frequency of cerebellar vermis degeneration. The genetic analysis (i) showed strong linkage between the disease and the 19p13 microsatellite markers in a region which widely overlaps that previously reported and (ii) set a new distal boundary of the gene-containing region. Combining present and previous mapping data, the gene of episodic etaxia type 2 is most probably located in an interval approximately 1.5 Mb between markers D19S221 and D19S226.

Acetazolamide↗
PubMed1997

Episodic ataxia type 2 (EA2) and spinocerebellar ataxia type 6 (SCA6) due to CAG repeat expansion in the CACNA1A gene on chromosome 19p.

Point mutations of the CACNA1A gene coding for the alpha 1A voltage-dependent calcium channel subunit are responsible for familial hemiplegic migraine (FHM) and episodic ataxia type 2 (EA2). In addition, expansions of the CAG repeat motif at the 3' end of the gene, smaller than those responsible for dynamic mutation disorders, were found in patients with a progressive spinocerebellar ataxia, named SCA6. In the present work, the analysis of two new families with small CAG expansions of the CACNA1A gene is presented. In one family, with a clinical diagnosis of EA2, a CAG23 repeat allele segregated in patients showing different interictal symptoms, ranging from nystagmus only to severe progressive cerebellar ataxia. No additional mutations in coding and intron-exon junction sequences in disequilibrium with the CAG expansion were found. In the second family, initially classified as autosomal dominant cerebellar ataxia of unknown type, an inter-generational allele size change showed that a CAG20 allele was associated with an EA2 phenotype and a CAG25 allele with progressive cerebellar ataxia. These results show that EA2 and SCA6 are the same disorder with a high phenotypic variability, at least partly related to the number of repeats, and suggest that the small expansions may not be as stable as previously reported. A refinement of the coding and intron-exon junction sequences of the CACNA1A gene is also provided.

Adolescent↗
PubMed1997

Non-DYT1 dystonia in a large Italian family.

A large non-Jewish Italian family affected by idiopathic torsion dystonia with autosomal dominant transmission and almost complete penetrance is reported. The prevalent phenotype was characterised by early onset with cranial-cervical involvement and progression to a segmental distribution; progression to generalisation was also found. Among 45 people examined, 14 were considered definitely or probably affected by idiopathic torsion dystonia. Eight definitely affected members had mean age (SD) at onset of 15.6 (12.5); idiopathic torsion dystonia started in the cranial-cervical region in six of them, in the upper limbs in two; in four cases dystonia progressed to other body regions, in two cases a generalisation was seen. Linkage analysis with 9q34 markers excluded the region containing the DYT1 locus in this family; linkage to the dopa-responsive dystonia markers was also excluded. A comparison of the phenotype in the present family and other non-DYT1 families shows striking overlapping features differing from those of DYT1 idiopathic torsion dystonia.

Adult↗
PubMed1996

Construction of a YAC contig covering human chromosome 6p22.

A contig covering human chromosome 6p22 that consists of 134 YAC clones aligned based on the presence/absence of 52 DNA markers is presented. This contig overlaps with the 6p23 contig at its telomeric end and with the 6p21.3 contig at its centromeric end. The order of loci within the contig resolves the relative positions of several genetically mapped markers. Among the additional markers used here, there are eight novel PCR assays. The 12 known genes and anonymous ESTs located within the contig establish a first step toward a transcriptional map of this region. The instability of YAC clones observed during this work is also discussed.

Chromosome Mapping↗
PubMed1996

Genetic fitness in Huntington's Disease and Spinocerebellar Ataxia 1: a population genetics model for CAG repeat expansions.

An analysis of genetic fitness was performed in Huntington's Disease (HD) and Spinocerebellar Ataxia 1 (SCA1) families. Two partially overlapping samples were used: clinically defined HD and SCA1 patients from families ascertained in definite geographical areas, and molecularly typed carriers of HD and SCA1 mutations (CAG trinucleotide expansions). In both cases, a control group of normal relatives was used. HD and SCA1 patients born before 1915-20 had more children than normal controls. Carriers of HD and SCA1 mutations, all in the low/medium expansion range (37-49 and 47-54 CAG repeats respectively), had a higher number of children than controls up to more recent times (1935-1950). The reproduction of heterozygotes for large expansions could be analysed only in subjects born after 1950 and provided indirect evidence of a lower than normal number of children. The above results fit a model based on a differential fitness according to the degree of expansion. Such a model predicts that 1) up to relatively recently the frequency of alleles in the low/medium range has been maintained or even increased by the increased fitness of their carriers, as well as by new mutations, and 2) the frequency of large expansions, part of which are lost at each generation, is maintained through further expansions of alleles in the low/medium expansion range. The implications of such a model on linkage disequilibrium and the possible spread of these diseases in future generations are discussed.

Age of Onset↗
PubMed1996

Phenotypic characterization of individuals with 30-40 CAG repeats in the Huntington disease (HD) gene reveals HD cases with 36 repeats and apparently normal elderly individuals with 36-39 repeats.

Abnormal CAG expansions in the IT-15 gene are associated with Huntington disease (HD). In the diagnostic setting it is necessary to define the limits of the CAG size ranges on normal and HD-associated chromosomes. Most large analyses that defined the limits of the normal and pathological size ranges employed PCR assays, which included the CAG repeats and a CCG repeat tract that was thought to be invariant. Many of these experiments found an overlap between the normal and disease size ranges. Subsequent findings that the CCG repeats vary by 8 trinucleotide lengths suggested that the limits of the normal and disease size ranges should be reevaluated with assays that exclude the CCG polymorphism. Since patients with between 30 and 40 repeats are rare, a consortium was assembled to collect such individuals. All 178 samples were reanalyzed in Cambridge by using assays specific for the CAG repeats. We have optimized methods for reliable sizing of CAG repeats and show cases that demonstrate the dangers of using PCR assays that include both the CAG and CCG polymorphisms. Seven HD patients had 36 repeats, which confirms that this allele is associated with disease. Individuals without apparent symptoms or signs of HD were found at 36 repeats (aged 74, 78, 79, and 87 years), 37 repeats (aged 69 years), 38 repeats (aged 69 and 90 years), and 39 repeats (aged 67, 90, and 95 years). The detailed case histories of an exceptional case from this series will be presented: a 95-year-old man with 39 repeats who did not have classical features of HD. The apparently healthy survival into old age of some individuals with 36-39 repeats suggests that the HD mutation may not always be fully penetrant.

Adult↗
PubMed1995

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL). Clinical, neuroimaging, pathological and genetic study of a large Italian family.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a rare hereditary stroke disease. The gene has been recently mapped, in two French families, on chromosome 19q12 between two highly polymorphic genetic markers. We report on a new large Italian family affected with this disease, which is characterized by recurrent stroke episodes, focal neurological deficits progressing to pseudo-bulbar palsy, and dementia. Multiple deep infarcts and diffuse leucoencephalopathy were revealed by MRI and brain histopathology showed abnormalities of arterial media. A genetic study performed with microsatellite markers from region 19q12 showed that the disease locus lies in an interval largely overlapping that already described and is closely linked to two microsatellite markers, D19S212 and D19S222. A joint analysis of genotypic and phenotypic data shows that diffuse leucoencephalopathy is a reliable sign of the disease in otherwise normal 50%-risk subjects over the age 30 years and that penetrance of stroke episodes or dementia is most likely complete around age 60 years.

Adult↗
PubMed1994

The trinucleotide repeat expansion on chromosome 6p (SCA1) in autosomal dominant cerebellar ataxias.

Affected members of 73 families with a variety of autosomal dominant late onset cerebellar ataxias (ADCAs) were investigated for the trinucleotide (CAG) repeat expansion which is found in pedigrees exhibiting linkage to the SCA1 locus on chromosome 6. Most of the families were too small for linkage analysis. The mutation was only found in ADCA type I, in 19 out of 38 such kindreds investigated (50%). It was slightly more common in Italian (59%) than British (50%) families, and was also found in Malaysian, Bangladeshi and Jamaican kindreds. Overall, ADCA type I patients with the expansion had a lower incidence of hyporeflexia and facial fasciculation than those without. The trinucleotide expansion was not found in eight families with ADCA and maculopathy or 24 kindreds with a pure type of ADCA, confirming that these syndromes are genetically distinct. It was also not detected in 12 patients with sporadic degenerative ataxias. DNA analysis for the SCA1 mutation is useful diagnostically in single patients or small families, and can be used for presymptomatic testing where appropriate.

Adolescent↗
PubMed1994

Effect of trinucleotide repeat length and parental sex on phenotypic variation in spinocerebellar ataxia I.

Trinucleotide repeat expansion has been found in 64 subjects from 19 families: 57 patients with SCA1 and 7 subjects predicted, by haplotype analysis, to carry the mutation. Comparison with a large set of normal chromosomes shows two distinct distributions, with a much wider variation among expanded chromosomes. The sex of transmitting parent plays a major role in the size distribution of expanded alleles, those with > 54 repeats being transmitted by affected fathers exclusively. Our data suggest that alleles with > 54 repeats have a reduced chance of survival; these appear to be replaced in each generation by further expansion of alleles in the low- to medium-expanded repeat range, preferentially in male transmissions. Detailed clinical follow-up of a subset of our patients demonstrates significant relationships between increasing repeat number on expanded chromosomes and earlier age at onset, faster progression of the disease, and earlier age at death.

Adult↗
PubMed1993

Trinucleotide repeat length instability and age of onset in Huntington's disease.

The initial observation of an expanded and unstable trinucleotide repeat in the Huntington's disease gene has now been confirmed and extended in 150 independent Huntington's disease families. HD chromosomes contained 37-86 repeat units, whereas normal chromosomes displayed 11-34 repeats. The HD repeat length was inversely correlated with the age of onset of the disorder. The HD repeat was unstable in more than 80% of meiotic transmissions showing both increases and decreases in size with the largest increases occurring in paternal transmissions. The targeting of spermatogenesis as a particular source of repeat instability is reflected in the repeat distribution of HD sperm DNA. The analysis of the length and instability of individual repeats in members of these families has profound implications for presymptomatic diagnosis.

Adult↗
PubMed1993

The gene for spinal cerebellar ataxia 1 (SCA1) is flanked by two closely linked highly polymorphic microsatellite loci.

The gene for one form of autosomal dominant spinal cerebellar ataxia (SCA1), is mapped by linkage to chromosome 6p, very close to the microsatellite locus D6S89. Eight large Italian kindreds segregating SCA1, as defined by very close linkage to D6S89, were genotyped with five microsatellite markers linked closely to D6S89, all mapping within a 6 cM interval on 6p. Multipoint linkage analysis and haplotypes from recombinants map SCA1 between two of these markers, D6S274 and D6S259, 5-6 cM apart. A single rare four marker haplotype within this interval shows linkage disequilibrium with the disease locus in southern Italy and is transmitted with SCA1 in five kindreds originating from this area.

Alleles↗
PubMed1993

The gene for autosomal dominant spinocerebellar ataxia (SCA1) maps centromeric to D6S89 and shows no recombination, in nine large kindreds, with a dinucleotide repeat at the AM10 locus.

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant disorder which is genetically linked to the short arm of chromosome 6, telomeric to the human major histocompatibility complex (HLA) and very close to D6S89. Previous multipoint linkage analysis using HLA, D6S89, and SCA1 suggested that SCA1 maps centromeric to D6S89. Data from this study using nine large kindreds indicate a maximum lod score between SCA1 and D6S89 of 67.58 at a maximum recombination fraction of .004. To localize SCA1 more precisely, we identified five dinucleotide polymorphisms near D6S89. Genotypic analyses at these polymorphic loci were carried out in nine multigeneration SCA1 kindreds and in the Centre d'Etude du Polymorphisme Humain reference families. A new marker, AM10GA, demonstrates no recombination with SCA1. The maximum lod score for AM10GA linkage to SCA1 is 42.14 at a recombination fraction of 0. Linkage analysis and analysis of recombination events confirm that SCA1 maps centromeric to D6S89 and establish the following order: CEN-D6S109-AM10GA/SCA1-D6S89-LR40-D6S20 2-TEL.

Adult↗
PubMed1992

Child with manifestations of dermotrichic syndrome and ichthyosis follicularis-alopecia-photophobia (IFAP) syndrome.

We report on a boy with short stature, mental retardation, seizures, follicular ichthyosis, generalized alopecia, hypohydrosis, enamel dysplasia, photophobia, congenital aganglionic megacolon, inguinal hernia, vertebral, renal and other anomalies, and a normal chromosome constitution. The clinical findings include all the features that dermotrichic and ichthyosis follicularis-alopecia-photophobia (IFAP) syndrome have in common and in addition those that characterize IFAP syndrome (photophobia, recurrent respiratory infections, etc.), those that are present only in dermotrichic syndrome (nail anomalies, hypohydrosis, megacolon, vertebral defects, etc.) and additional ones (enamel dysplasia, renal anomalies, inguinal hernia, etc.). Two maternal uncles were referred as being affected by alopecia and ichthyosis suggesting X-linked recessive transmission. Various hypotheses concerning the relationship between the 2 syndromes and the present case are discussed.

Alopecia↗
PubMed1992

Autosomal dominant pure cerebellar ataxia. Neurological and genetic study.

A family with late-onset autosomal dominant pure cerebellar ataxia was studied both neurologically and genetically. Neuroimaging and electrophysiological results were in agreement with the clinical evidence showing involvement of the cerebellar system only, even many years after onset. No atrophy of inferior olives was observed by magnetic resonance imaging, while cerebellar atrophy was extremely marked. A very slow disease progression was observed in all patients. The disease can be differentiated from autosomal dominant olivo-ponto-cerebellar atrophies, and in particular from spinocerebellar ataxia type 1 mapping on chromosome 6p, which shows an early multisystemic involvement and a more rapid progression toward inability. A genetic study of the family with the 6p DNA marker D6S89 closely linked to the spinocerebellar ataxia type 1 locus was performed. Results showed significant exclusion of a linkage between the disease and the marker within a distance of 8.5% recombination, indicating that genetic heterogeneity underlies phenotypic differences.

Adult↗
PubMed1992

HLA-linked spinocerebellar ataxia: a clinical and genetic study of large Italian kindreds.

Five families with late onset autosomal dominant spinocerebellar ataxia, were studied. Linkage between the disease and HLA loci on the short arm of chromosome 6 was shown in the two largest pedigrees. Clinical study of 26 patients and neuropathological study in one are reported. The disease was characterized by cerebellar and pyramidal involvement variably associated with cranial nerve and peripheral nervous system disorders. A remarkable concordance of the main clinical features was observed in patients with similar disease duration. Comparison with previous reports of HLA-linked spinocerebellar ataxia kindreds showed differences in clinical phenotypes. Although these might be due to genetic variation, the hypothesis is suggested that the phenotype might appear more homogeneous if disease duration is taken into account.

Adult↗
PubMed1992

DNA markers in diagnosis of adult dominant polycystic kidney disease.

We report the results of a biological and molecular study carried out on 11 Italian families, with a total of 111 individuals in which adult dominant polycystic kidney disease segregates. A restriction fragment length polymorphism analysis was performed. Two families have shown a genetic heterogeneity even if not phenotypically different from the other ones: they resulted unlinked to 16p markers. A prenatal diagnosis has been performed in a family of the linked type.

DNA↗