Phenotypic spectrum of MFN2 mutations in the Spanish population.

INTRODUCTION: The most common form of axonal Charcot-Marie-Tooth (CMT) disease is type 2A, caused by mutations in the mitochondrial GTPase mitofusin 2 (MFN2). OBJECTIVE: The objective of our study is to establish the incidence of MFN2 mutations in a cohort of Spanish patients with axonal CMT neuropathy. MATERIAL AND METHODS: Eighty-five families with suspected axonal CMT were studied. All MFN2 exons were studied through direct sequencing. A bioenergetics study in fibroblasts was conducted using a skin biopsy taken from a patient with an Arg468His mutation. RESULTS: Twenty-four patients from 14 different families were identified with nine different MFN2 mutations (Arg94Trp, Arg94Gln, Ile203Met, Asn252Lys, Gln276His, Gly296Arg, Met376Val, Arg364Gln and Arg468His). All mutations were found in the heterozygous state and four of these mutations had not been described previously. MFN2 mutations were responsible for CMT2 in 16% +/- 7% of the families studied and in 30.8 +/- 14.2% (12/39) of families with known dominant inheritance. The bioenergetic studies in fibroblasts show typical results of MFN2 patients with a mitochondrial coupling defect (ATP/O) and an increase of the respiration rate linked to complex II. CONCLUSION: It is concluded that mutations in MFN2 are the most frequent cause of CMT2 in this region. The Arg468His mutation was the most prevalent (6/14 families), and our study confirms that it is pathological, presenting as a neuropathy in a mild to moderate degree. This study also demonstrates the value of MFN2 studies in cases of congenital axonal neuropathy, especially in cases of dominant inheritance, severe clinical symptoms or additional symptoms such as optic atrophy.

A kindred with cerebellar ataxia and thermoanalgesia.

OBJECTIVE: To characterise the clinical, neurophysiological, neuropathological and genetic features of a family with cerebellar autosomal dominant ataxia. DESIGN: Patients were submitted to clinical, neuroradiological and neurophysiological examinations. Molecular studies were undertaken to exclude SCAs 1-3, 6-8, 12 and 17. Studies were performed to rule out linkage to SCA4 on chromosome 16, and for all still uncharacterised SCA loci. Neuropathological examination of the proband was performed with immunocytochemistry. RESULTS: These patients presented a late onset cerebellar ataxia with thermoanalgesia and deep sensory loss. Unlike in SCA4, reflexes were preserved. MRI revealed cerebellar, medullar and spinal cord atrophy. Neurophysiological studies showed absence or marked reduction of the sensory nerve action potentials and somatosensory evoked potentials in lower and upper limbs but preservation of the soleus H reflex. No triplet repeat expansion mutations in the studied SCA genes were identified. Our studies ruled out linkage of the disease to the SCA4 locus on chromosome 16 and the remaining reported SCA loci. The neuropathological study of the proband revealed severe loss of Purkinje cells and dentate neurons. The inferior olive and lower cranial nerve nuclei also showed extensive cell loss. Posterior columns and spinocerebellar tracts were demyelinated. Ubiquitin immunoreactive intranuclear inclusions were absent. CONCLUSION: This kind of cerebellar ataxia, associated with thermoanalgesia as well as deep sensory loss with retained reflexes, does not associate to any known SCA loci. Therefore, we identify and describe a new form of late onset dominant spinocerebellar ataxia.

Two Spanish families with Charcot-Marie-Tooth type 2A: clinical, electrophysiological and molecular findings.

Mutations in the Mitofusin 2 (MFN2) gene have been related to the axonal type of Charcot-Marie-Tooth type 2 (CMT 2A). We report the first two Spanish families with CMT 2 and mutations in MFN2 gene. Molecular studies of one family with late onset revealed the novel mutation Arg364Gln. The affected family members presented mild clinical and electrophysiological worsening after 14 years of follow-up. The other family presented an early onset and optic atrophy. Molecular studies revealed the Arg94Gln mutation. This is the first report of a family in which this mutation is related to optic atrophy. Molecular analysis aimed at detecting mutations of MFN2 could be extremely useful in mild axonal neuropathies with slow evolution and indispensable in cases of dominant inheritance or optic atrophy. Population studies of mutations in MFN2 should be undertaken to discover the real frequencies in the Mediterranean area.

Genetic analysis of 27 Spanish patients with hemiplegic migraine, basilar-type migraine and childhood periodic syndromes.

Familial hemiplegic migraine (FHM) is a rare type of migraine with aura. Mutations in three genes have been described in FHM patients: CACNA1A (FHM1), ATP1A2 (FHM2) and SCN1A (FHM3). We screened 27 Spanish patients with hemiplegic migraine (HM), basilar-type migraine or childhood periodic syndromes (CPS) for mutations in these three genes. Two novel CACNA1A variants, p.Val581Met and p.Tyr1245Cys, and a previously annotated change, p.Cys1534Ser, were identified in individuals with HM, although they have not yet been proven to be pathogenic. Interestingly, p.Tyr1245Cys was detected in a patient displaying a changing, age-specific phenotype that began as benign paroxysmal torticollis of infancy, evolving into benign paroxysmal vertigo of childhood and later becoming HM. This is the first instance of a specific non-synonymous base change being described in a subject affected with CPS. The fact that the molecular screen identified non-synonymous changes in < 15% of our HM patients further stresses the genetic heterogeneity underlying the presumably monogenic forms of migraine.

A nuclear defect in the 4p16 region predisposes to multiple mitochondrial DNA deletions in families with Wolfram syndrome.

Wolfram syndrome is a progressive neurodegenerative disorder transmitted in an autosomal recessive mode. We report two Wolfram syndrome families harboring multiple deletions of mitochondrial DNA. The deletions reached percentages as high as 85-90% in affected tissues such as the central nervous system of one patient, while in other tissues from the same patient and from other members of the family, the percentages of deleted mitochondrial DNA genomes were only 1-10%. Recently, a Wolfram syndrome gene has been linked to markers on 4p16. In both families linkage between the disease locus and 4p16 markers gave a maximum multipoint lod score of 3.79 at theta = 0 (P<0.03) with respect to D4S431. In these families, the syndrome was caused by mutations in this nucleus-encoded gene which deleteriously interacts with the mitochondrial genome. This is the first evidence of the implication of both genomes in a recessive disease.

Effects of chronic restraint stress on the global DNA methylation profile of rat lung cells: Modulation by physical exercise.

The potential of behavioral stress to affect epigenetic mechanisms of non-encephalic tissues is still underestimated. In the present study we evaluated the effects of chronic behavioral stress on the DNA methylation profile of rat lung cells. Furthermore, we evaluated the potential of physical exercise to modulate the changes evoked by behavioral stress in lung cells. Male Wistar rats were divided into four experimental groups: (1) animals submitted to chronic restraint stress (CRS) (ST group) during the period of the 67th-80th postnatal day (PND); (2) animals submitted to physical exercise (EX group) during the 53rd-79th PND; (3) animals submitted to swimming during the 53rd-79th PND and to CRS during the 67th-80th PND (EX-ST group); and (4) animals not submitted to stress or swimming protocols (CTL). Global DNA methylation was quantified using an ELISA-based approach and gene expression was evaluated by real time PCR. A decreased global DNA methylation profile was observed in the ST group, however physical exercise demonstrated protection of lung cells from this stress-related hypomethylation. Increased expression of the Dnmt1 gene was evidenced in the ST group, whereas physical exercise was shown to protect lung cells from this stress-related effect in the EX-ST group. Comparative analysis of the ST and EX groups revealed opposite effects on the expression of Dnmt3a and Dnmt3b; however, a stress-related increase in expression of Dnmt3a and Dnmt3b was not seen in the EX-ST group. Our data showed that behavioral stress induced significant changes in the DNA methylation profile of rat lung cells and that this could be modulated by physical exercise.

Physical exercise affects the epigenetic programming of rat brain and modulates the adaptive response evoked by repeated restraint stress.

Epigenetics has recently been linked to molecular adaptive responses evoked by physical exercise and stress. Herein we evaluated the effects of physical exercise on global DNA methylation and expression of the Dnmt1 gene in the rat brain and also verified its potential to modulate responses evoked by repeated restraint stress (RRS). Wistar rats were classified into the following experimental groups: (1) physically active (EX): animals submitted to swimming during postnatal days 53-78 (PND); (2) stress (ST): animals submitted to RRS during 75-79PND; (3) exercise-stress (EX-ST): animals submitted to swimming during 53-78PND and to RRS during 75-79PND, and (4) control (CTL): animals that were not submitted to intervention. Samples from the hippocampus, cortex and hypothalamus were obtained at 79PND. The global DNA methylation profile was assessed using an ELISA-based method and the expression of Dnmt1 was evaluated by real-time PCR. Significantly increased methylation was observed in the hypothalamus of animals from the EX group in comparison to CTL. Comparative analysis involving the EX-ST and ST groups revealed increased global DNA methylation in the hippocampus, cortex, and hypothalamus of EX-ST, indicating the potential of physical exercise in modulating the responses evoked by RRS. Furthermore, decreased expression of the Dnmt1 gene was observed in the hippocampus and hypothalamus of animals from the EX-ST group. In summary, our data indicate that physical exercise affects DNA methylation of the hypothalamus and might modulate epigenetic responses evoked by RRS in the hippocampus, cortex, and hypothalamus.

Spinocerebellar ataxia type 2 (SCA2) with white matter involvement.

Two sisters presented with olivopontocerebellar atrophy, neuronal loss in the substantia nigra, intranuclear ubiquitin-, ataxin-2-positive inclusions in neurons, and severe demyelination and axon loss of the cerebral white matter with no accompanying inflammatory pathology. The genetic study demonstrated a 22/36 CAG triplet expansion in the SCA2 gene in one of the sisters; SCA1, SCA3, SCA6, SCA7, SCA8, SCA12, SCA17 and DRPL were ruled out in this patient. The present report shows that severe cerebral white matter pathology may occur in the context of SCA2.

Effects of zidovudine in 30 patients with mild to end-stage AIDS dementia complex.

OBJECTIVE: Zidovudine (ZDV) is an inhibitor of HIV replication that may have a beneficial effect on patients with AIDS dementia complex (ADC). However, little is known about the association between long-term ZDV treatment and severity of ADC, ZDV dose or clinical and laboratory response to therapy. DESIGN: An open study on ZDV administration in 30 consecutive patients with ADC. SETTING: An infectious diseases hospital. PATIENTS: Thirty consecutive patients followed-up for 12 months. INTERVENTIONS: Three oral ZDV doses were used: 1000 mg (nine patients), 750 mg (eight patients) and 500 mg (13 patients) per day, depending on haematological status. MAIN OUTCOME MEASURES: Clinical and neurological examinations, neuropsychological evaluations, high-field brain magnetic resonance imaging (MRI) and 99mTc-HM-PAO single photon emission computerized tomography (SPECT). RESULTS: A favourable clinical response, defined as reversal to a less severe ADC stage (Price and Brew's criteria), was observed after 1, 3, 6, 9 and 12 months in 15, 22, 25, 19 and 14 patients, respectively. Neither severity of ADC at entry nor ZDV dose correlated with response to treatment. Seven patients died during the 12-month follow-up. The only factor associated with longer survival was ADC severity at entry (12-month survival, 0.94 and 0.53, in patients in stages 1 or 2 and in stages 3 or 4, respectively; P < 0.01). After 6-12 months of ZDV treatment six patients who initially responded to therapy showed a relapse in initial ADC stage, and two patients a less severe neurological deterioration. Neuropsychological evaluations showed significant improvement in the Wisconsin Card-Sorting test (P = 0.006 for categories, P = 0.029 for perseverative errors), which is particularly sensitive to cognitive and frontal-lobe type functions. Brain MRI revealed a reduction of the extent of white matter lesions in six out of 13 patients, who also showed clinical improvement. SPECT scanning revealed a reduction in the extent of uptake defects concomitant with clinical response in nine out of 14 patients. CONCLUSIONS: ZDV is effective in most patients with mild to end-stage ADC, although the benefit is sometimes only transient; several relapses and deaths occurred after the sixth month of treatment.

Methods for detecting early signs of AIDS dementia complex in asymptomatic HIV-1-infected subjects.

OBJECTIVES: To determine the optimal diagnostic procedures for identifying early signs of AIDS dementia complex (ADC) in asymptomatic HIV-1-infected individuals, in order to prevent further cognitive function impairment by early treatment. DESIGN: Study patients had been referred electively and consecutively to hospital; all had been referred for the first time and gave informed consent. Inclusion criteria were (1) lack of history and/or symptoms of psychosis and neurological disorders; (2) lack of active viral, protozoan or fungal pathology; (3) abstinence from heroin and/or cocaine for at least 6 months before baseline evaluation. SETTINGS: Subjects were seen at the L. Spallanzani Hospital for Infectious Diseases, Rome, Italy between March 1989 and March 1991. PARTICIPANTS: Eighty-two asymptomatic HIV-1-infected subjects: 41 drug users, 27 homosexuals and 14 heterosexuals. MAIN OUTCOME MEASURES: All subjects were evaluated using Wechsler-Bellevue I, Benton C form and Bender tests. Thirty-nine subjects underwent single-photon emission computed tomography (SPECT) and 12 magnetic resonance imaging (MRI). The immunological status of each subject was determined. RESULTS: On psychometric testing, 23 out of the 82 (28%) asymptomatic subjects had a mental decay percentage (MD%) > or = 20%. Cerebral perfusion abnormalities were detected in 31 out of 39 (79.48%) subjects who underwent SPECT; MRI abnormalities were observed in seven out of 12 (58%) subjects. Twelve out of 23 subjects with MD% > or = 20, 15 out of 29 subjects with SPECT abnormalities and four out of seven patients with MRI abnormalities had total CD4+ lymphocyte counts > or = 500 x 10(6)/l. CONCLUSIONS: The high incidence of abnormal SPECT and of MD% > or = 20 in asymptomatic HIV-1-infected patients, and the lack of correlation between immunological status and degree of mental decay, SPECT and MRI abnormalities raise many questions about subclinical HIV-1 neurological disease.

Identification of seven novel SNPS (five nucleotide and two amino acid substitutions) in the connexin31 (GJB3) gene.

Connexin31 (GJB3) has been associated with hearing impairment and erythrokeratodermia variabilis. We have analyzed this gene in samples from patients with peripheral neuropathies, deafness and controls and have found several single nucleotide polymorphisms (SNPs). In the noncoding exon 1 of GJB3 two small deletions, 581del2 and 632del4 (GenBank accession number AF052692), were found at frequencies of 30% and 14%, respectively. In exon 2 we found two amino acid changes, R32W (1227C-T) and V200I (1731G-A), and three nucleotide variants not affecting the amino acid sequence, 1610G-A, 1700C-T and 1931C-T. Most of these changes were found at similar frequencies in patients with deafness, patients with peripheral neuropathies and control subjects. V200I, 1700C-T and 1610G-A were found associated in three unrelated patients with deafness and in a fourth patient with peripheral neuropathy, but were not detected in control subjects.

Linkage of DFNB1 to non-syndromic neurosensory autosomal-recessive deafness in Mediterranean families.

Recent studies show a susceptibility locus (DFNB1) responsible for non-syndromic neurosensory autosomal-recessive deafness (NSRD) mapping to the pericentromeric region of chromosome 13q. In order to better understand the frequency with which DFNB1 is the gene for deafness in our patient population and the role of DFNB1 in Caucasians, we performed a genetic linkage study with four microsatellite markers linked to DFNB1 in a total of 48 independent Mediterranean families, of which 30 and 18 were of Italian and Spanish descent, respectively. A maximum two-point lod score of 7.28 was found with marker D13S115 at a recombination frequency of theta 0.1. Significant lod scores were also obtained for D13S143, D13S292 and D13S175. Genetic heterogeneity was confirmed using the HOMOG program which indicated absence of linkage to DFNB1 in approximately 21% of the sample. This study clearly demonstrates that DFNB1 plays an important role in 79% of Mediterranean families with NSRD. Furthermore, results from multipoint analysis predict that the DFNB1 gene maps between markers D13S175 and D13S115 which are separated by approximately 14.2 cM.

Estimation of the mutation frequencies in Charcot-Marie-Tooth disease type 1 and hereditary neuropathy with liability to pressure palsies: a European collaborative study.

A European collaboration on Charcot-Marie-Tooth type 1 (CMT1) disease and hereditary neuropathy with liability to pressure palsies (HNPP) was established to estimate the duplication and deletion frequency, respectively, on chromosome 17p11.2 and to make an inventory of mutations in the myelin genes, peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ) and connexin 32 (Cx32) located on chromosomes 17p11.2, 1q21-q23 and Xq13.1, respectively. In 70.7% of 819 unrelated CMT1 patients, the 17p11.2 duplication was present. In 84.0% of 156 unrelated HNPP patients, the 17p11.2 deletion was present. In the nonduplicated CMT1 patients, several different mutations were identified in the myelin genes PMP22, MPZ and Cx32.

Clinical, neuropathologic, and genetic studies of a large spinocerebellar ataxia type 1 (SCA1) kindred: (CAG)n expansion and early premonitory signs and symptoms.

We report the clinical, neuropathologic, and genetic studies of a large kindred (family M-ADCA1) with autosomal dominant spinocerebellar ataxia type 1 (SCA1), ascertained in 41 members, with clinical data available in twenty-two. The mean age of onset was 36.3 +/- 6.2 years (ages, 26 to 52), the mean duration of the disease was 15.8 +/- 6.5 years (range, 10 to 28 years), and the mean age at death was 54.1 +/- 9.5 years (ages, 39 to 72). Premonitory signs and symptoms appeared earlier than the usual onset symptoms in many of the clinically unaffected patients who inherited the mutated SCA1 gene. Anticipation was present when we compared the seventh and eighth generations. A more severe course of the disease occurred in offspring of affected males. Neuropathologic examination, performed on three patients, showed the usual findings of SCA1; Golgi and immunocytochemistry studies suggested primary damage of the Purkinje cells. We analyzed the CAG-repeat mutation responsible for the SCA1 phenotype in a total of 41 family members. There was expansion in 19 subjects (10 clinically affected, seven with early signs and symptoms, and two asymptomatic individuals), and all showed heterozygosity, with one allele between 41 and 59 repeats (SCA1 mutation) and the other in the range of 6 to 39 repeats (normal range). The clinical analysis of "at risk" patients with the SCA1 mutation showed that minor signs and symptoms begin before full clinical diagnosis, and these premonitory manifestations can herald full development of SCA1 by years.

Linkage analysis in Spanish families with nonspecific X-linked mental retardation: Significant linkage at Xq13-q21.

Mental retardation (MR) is a genetically heterogeneous, clinically variable condition. Many cases of MR are linked to the X chromosome. The aim of this study was to identify candidate loci for nonspecific MR in Spanish samples. We selected seven families with nonspecific MR and a pattern of inheritance compatible with an X-linked disorder and a group of 26 sib pairs of mentally retarded individuals. We performed linkage analysis with a panel of 15 markers evenly distributed along the X chromosome. The study showed linkage to marker DXS8076, located in Xq21.1, by the lod score method (z = 2.11 at straight theta = 0.155) and the nonparametric extended relative pair analysis method (chi(2) = 5.32; P < 0.03). Genetic heterogeneity was found, with an estimated 75% of the families linked at recombination fraction straight theta = 0.10 to the DXS8076 locus (chi(2) = 9.51; P < 0.009). Xq13-q21 is one of the critical regions for X-linked MR previously reported, and our study supports the idea that this region may contain a locus for MR in Spanish patients.

Identification of WASP mutations in 14 Spanish families with Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency caused by mutations in the WASP gene. The disease is known to be associated with extensive clinical variability, and mutation studies indicate that genotypes are also highly variant among WAS patients. In this study, we performed mutation analysis of the WASP gene in 14 unrelated Spanish families by single strand conformation analysis (SSCA) and sequencing, resulting in the identification of a novel mutation and nine known mutations. No mutation was identified in one family. The ten different mutations include point mutations resulting in amino acid substitutions, stop codons, and small deletions and insertions causing frameshifts. Missense mutations were preferentially located in the amino-terminal part of the protein, exons 2 and 4, whereas stop and frameshift mutations were located in the carboxyl-terminal region, exons 10 and 11. However, in two families, two missense mutations in exon 11 were identified. Our study demonstrates that WASP genotypes have some concordance with the patients' phenotypes, although mutation 1019delC, identified in a family with several affected members, resulted in high intrafamilial clinical variability.

Anticipation is not associated with CAG repeat expansion in parent-offspring pairs of patients affected with schizophrenia.

With the rationale that a disease that presents with anticipation could be associated with expansion of trinucleotide repeats, we selected parent-offspring pairs of schizophrenia patients with earlier age at onset in the filial generation to measure the expansion of CAG repeats using the repeat expansion detection (RED) method. Intergenerational comparisons were made for age at onset, length of CAG repeats, and clinical variables. Although the patients from the filial generation became affected 13 years earlier than the parents (P < 0.0005), we did not find larger CAG repeats in the offspring. No association was found between size of CAG repeat and age at onset or with any other clinical variable. Overall, the frequency of patients with CAG repeats longer than 40 was 32%, which was similar to that observed in control subjects (27%). It is particularly noteworthy that in 86% of the pairs, the mother was the affected parent. In this Spanish sample with parent-offspring pairs presenting schizophrenia with clinical anticipation and apparent female bias of transmission, neither the phenomenon of anticipation nor disease status was associated with the expansion of CAG repeats.

Understanding the dynamics of Spinocerebellar Ataxia 8 (SCA8) locus through a comparative genetic approach in humans and apes.

Spinocerebellar Ataxia 8 (SCA8) is a neurodegenerative disorder caused by expansion of a trinucleotide repeat. We undertake a comparative genetic analysis among human populations and primate species in the normal variation range, where forces that shaped present diversity can be recognised. We determinate number of repeats of the short tandem repeat through allele length sizing and sequencing methods. Human allele distributions are very similar among populations, ruling out ethnicity as a genetic risk for allele expansion. Primate comparison shows human-specific features, with longer human alleles due to a novel variable trinucleotide repeat, not present in non-human primates, which increased the disease-causing expansion likelihood. SCA8 seems to be a human specific disease.

Enterogenous cyst of the spinal cord terminal cone. Clinical and radiological aspects (CT and MRI).

Enterogeneous cyst of the spinal cord are rare. They are the result of a dysembriogenetic error occurred in the third week of the embryo life. The cervical tract, followed by the caudal tract of the spinal cord, are their favourite sites. This work describes a case of neuroenteric cyst localized in the terminal cone of the spinal cord; CT and myelographic findings point to a generic cystic lesion; MR shows a sharp edge lesion, hypointense at T1 and hyperintense at T2, with signal uniformity similar to C.S.F. MR also allows the evaluation of any CSF pulsation in the cystic lesion and, in the presence of a cystic neoplasm, any signal changes in the adjacent parenchyma.

Cerebral blood flow in AIDS-related neurotoxoplasmosis: a preliminary 99mTc-HMPAO SPECT study.

Cerebral blood flow (CBF) was evaluated by gamma camera 99mTc-HMPAO SPECT in 11 patients with AIDS-related neurotoxoplasmosis and correlated with neurological findings and the results of CT and MRI. Evident CBF abnormalities were observed in all patients with involvement of at least two cerebral lobes. In 10 patients the abnormalities were bilateral and in 8 patients basal ganglia were involved; no specific hypoperfusion pattern was however evident. Focal lesions were found in 7 patients by CT (sensitivity: 63.6%) and in 10 patients by MRI (sensitivity: 90.9%). It may be concluded that neurotoxoplasmosis in AIDS patients is associated with a high prevalence of focal cortical and subcortical hypoperfusion but that the scintigraphic findings are not specific; that HMPAO SPECT may show focal hypoperfusion in patients with normal CT studies and/or non-focal MRI abnormalities; that the hypoperfusion may be more extensive than the corresponding MRI lesion(s) and that it may be present even in areas with normal MRI signals; and that more experience and longitudinal studies are needed to assess the possible impact of HMPAO SPECT on follow-up and therapy monitoring.