J. J. Poza

Autosomal dominant lateral temporal epilepsy: Clinical and genetic study of a large basque pedigree linked to chromosome 10q

We report a large family with a temporal partial epilepsy syndrome inherited in an autosomal dominant mode, with a penetrance of about 80%. This epilepsy syndrome is benign, with age of onset in the second or third decade of life. It is characterized by rare partial seizures, usually secondarily generalized, arising mostly during sleep, without postictal confusion. There is a good response to the antiepileptic therapy but often a recurrence of seizures after drug withdrawal. The partial component, visual (lights, colors, and simple figures) or auditory (buzzing or “humming like a machine”), the existence of temporo‐occipital interictal electroencephalographic epileptiform abnormalities, and the hypoperfusion in the temporal lobe detected by interictal hexamethylpropyleneamine oxime–technetium 99m (HMPAO‐Tc99m) single‐photon emission computed tomography, strongly suggest a lateral temporal lobe origin. The genetic analysis found linkage to chromosome 10q, and localized a gene in a 15‐cM interval that overlaps a previously found localization for partial epilepsy in a large three‐generation family. This syndrome could be called autosomal dominant lateral temporal epilepsy. Ann Neurol 1999;45:182–188

Prevalence of Parkinson’s disease and other types of Parkinsonism

Abstract.Objectives:To assess the prevalence of Parkinson’s disease and parkinsonism in two Spanish populations (Irun and Hondarribia, Bidasoa Region) and to compare the results with those of similar surveys.Methods:The survey included 2000 participants aged 65 years or older in a door-to-door, three-phase design. In the screening phase we used the SNES (Sicilian Neuro-Epidemiologic Study) screening questionnaire, which has 100% sensitivity. In phases 2 and 3 we carried out a 3-year follow-up of all cases diagnosed with parkinsonism in phase 2. Progressively stricter diagnostic criteria were chosen in order to minimize the impact of false positives on the final results.Results:The prevalence of Parkinson’s disease (PD) was 1.5 % (95% confidence interval, 0.9 to 2.3) and the prevalence of other types of parkinsonism (OP) was 1.1 % (95% confidence interval 0.6 to 1.9). The overall prevalence by age group was 0.4 % (65–74 years), 4.7% (75–84 years), and 2.9% (≥ 85 years) for Parkinson’s disease and 0.7%, 2%, and 3.9 % for parkinsonism, respectively. The other parkinsonism prevalence was 1.3 % in men and 1.6 % in women.Conclusions:These prevalence rates are similar than those found in studies made in other European countries. The prevalence of both Parkinson’s disease and other types of parkinsonism increased with age, with no significant differences between men and women.

The validity of Hodkinson's Abbreviated Mental Test for dementia screening in Guipuzcoa, Spain

The objective of this research was to evaluate the validity of Hodkinson’s Abbreviated Mental Test (AMT) in screening for dementia and to identify the optimum cut‐off point to use in a prevalence survey. The study included two groups of persons: (i) a random sample of 183 individuals selected from census data, 96 of whom completed the study and (ii) another 36 persons with dementia were selected from a hospital outpatients department by sampling consecutive cases. The DSM‐IV criteria were used as the ‘gold standard’ to establish a diagnosis of dementia. The AMT was administered to the 132 participants who subsequently underwent independent clinical evaluation. In the community sample, 11 persons were diagnosed with dementia and 85 without. In the total sample, a score of 7 maximizes the efficacy of the test. The sensitivity for this cut‐off point is 91.5% (78.7–97.2%) and the specificity is 82.4% (72.2–89.5%). A score of 9 gives 100% sensitivity, but the proportion of false positives rises to 66%. Our results are consistent with other studies and suggest that the AMT is a valid instrument for use in screening for dementia in populations similar to the one in this study.

Prevalence of myotonic dystrophy in Guipúzcoa (Basque Country, Spain)

Prevalence figures for inherited neuromuscular disorders are important both for health care planning purposes and for evaluating the need for DNA diagnostic services for eugenic approaches. We screened for the prevalence of myotonic dystrophy (MyD) through extensive inquiry of neurologic and primary health services of Guipúzcoa (Basque Country, northern Spain) between 1989 and 1991. Typical adult-onset and neonatal cases and relatives at risk, suffering from a partial syndrome, were included. In the latter, molecular typing was performed with DNA probes close to the MyD gene to demonstrate the MyD gene carrier status. The high prevalence detected (26.5 cases per 100,000 population) could be explained by methodological factors, but intrinsic factors, such as a possible founder genetic effect or the quick growth of the Guipúzcoa population since the last century may contribute to one of the highest MyD prevalences in the world. In the future, the methodological basis for epidemiologic surveys of MyD must combine molecular technology with more-extensive family inquiries.

Prevalence of Essential Tremor: A Door-to-Door Survey in Bidasoa, Spain

Objectives: To assess the prevalence of essential tremor (ET) in two Spanish populations (Irun and Hondarribia, Bidasoa region) and to compare the results with those of similar surveys. Methods: The survey included 2,000 participants aged 65 years or older in a door-to-door, two-phase design. ET was defined as postural or kinetic tremor of the head or limbs. Results: ET prevalence after age adjustment was 4.8% (95% confidence interval, 3.6–6.4). Prevalence increased significantly with age and there were no sex differences. Conclusions: The age-adjusted prevalence rate of ET in people 65 years old and older in Bidasoa, Spain, is close to those described in other studies using a similar design and suggest no geographical variation. ET prevalence increases with age and has a similar distribution in males and females.

Contribution of molecular analyses to the estimation of the risk of congenital myotonic dystrophy.

A molecular analysis of the maternal and child CTG repeat size and intergenerational amplification was performed in order to estimate the risk of having a child with congenital myotonic dystrophy (CMD). In a study of 124 affected mother-child pairs (42 mother-CMD and 82 mother-non-CMD) the mean maternal CTG allele in CMD cases was three times higher (700 repeats) than in non-CMD cases (236 repeats). When the maternal allele was in the 50-300 repeats range, 90% of children were non-CMD. In contrast, when the maternal allele was greater than 300 repeats, 59% inherited the congenital form. Furthermore, the risk of having a CMD child is also related to the intergenerational amplification, which was significantly greater in the mother-CMD pairs than in the mother-non-CMD pairs. Although the risk of giving birth to a CMD child always exists for affected mothers, our data show that such a risk is considerably higher if the maternal allele is greater than 300 repeats.

Frequency of myotonic dystrophy gene carriers in cataract patients.

DNA samples from 231 unselected patients with cataracts were studied to determine the frequency of the DM mutation in cataract patients. A previous epidemiological study established a high prevalence of DM in the population of Guipúzcoa (Basque Country, Spain), 26.5 cases/100,000. We have found two carriers (0.9%) of the DM mutation in patients who are not related to any previously known DM family. The screening of the DM mutation in cataract patients should be restricted to young patients or people with multicoloured and iridescent opacities, in which the risk of carrying the DM premutation could be higher. Our results suggest that subjects with 38 to 80 repeats could constitute the genetic reservoir of the DM mutation.

Cancer risk in DM1 is sex-related and linked to miRNA-200/141 downregulation

Objective: Describe the incidence of cancer in a large cohort of patients with myotonic dystrophy type 1 (DM1) and to unravel the underlying molecular mechanisms. Methods: Standardized incidence ratios (SIRs) were calculated in the Gipuzkoa DM1 cohort (1985–2013), dividing observed numbers by expected numbers for all cancers combined and stratified by sex. An estimation of the expected incidence was achieved by multiplying the age- and sex-specific incidence rates from the Basque population cancer registry by the person-years observed in the study cohort. Large-scale gene expression of peripheral blood mononuclear cell samples derived from 10 individuals with DM1 (5 men, 5 women) and 10 healthy matched controls was analyzed by the Human Gene 1.0 ST Affymetrix microarray. Results: During 18,796 person-years of follow-up, corresponding to 424 patients with DM1, we observed 70 cancers in 62 patients giving a 1.81-fold risk (95% confidence interval [CI] 1.37–2.36), which was stronger in women than in men. Ovary (SIR 8.33, 95% CI 1.72–24.31) and endometrium (SIR 6.86, 95% CI 2.23–16.02) in women and thyroid (SIR 23.33, 95% CI 9.38–48.08) and brain (SIR 9.80, 95% CI 3.18–22.88) in both sexes were tumor sites with significantly higher risks in DM1. There were differences in gene expression between healthy controls and patients with DM1 and between men and women with DM1; all patients with DM1 combined and female patients with DM1 displayed significant downregulation of the microRNA (miRNA)-200c/141 tumor suppressor family. Conclusions: Oncologic risk is increased in DM1, especially in women and for gynecologic, brain, and thyroid cancer. Expression of the miRNA-200/miRNA-141 tumor suppressor family is decreased in women with DM1.

Frequency of intergenerational contractions of the CTG repeats in myotonic dystrophy.

Myotonic dystrophy (MD), an autosomal dominant multisystemic disorder with a high phenotypic variability, is the most common muscular dystrophy in adult life. The mutation underlying DM has been characterized as an expanded CTG trinucleotide repeat sequence in the 3′ untranslated region of a protein kinase gene on chromosome 19q13.2–13.3.

Myopathy with hexagonally cross-linked crystalloid inclusions: Delineation of a clinico-pathological entity

A novel myopathy characterized by hexagonally cross-linked tubular arrays has been reported in five patients. We studied the clinical and histopathological features of five additional unrelated patients with this myopathy. Patients experienced exercise intolerance with exercise-induced myalgia and weakness, without rhabdomyolysis. One patient additionally presented mild permanent pelvic girdle muscle weakness. Age at onset varied between 13 and 56 years. The inclusions were eosinophilic on H and E, bright red with modified Gomoris trichrome stains, present in type 2 fibers, and revealed immunoreactivity selectively for a caveolin-3-antibody. Ultrastructurally, the inclusions showed a highly organized, hexagonally cross-linked crystalloid structure. Mutations in the caveolin-3 encoding gene were excluded. Biochemical assessment of glycogenolysis in muscle was normal. Inherited or sporadic myopathy with hexagonally cross-linked tubular arrays is associated with a homogeneous clinical and histopathological phenotype. This myopathy should be included in the differential diagnosis of patients with exercise intolerance and myalgia.