Epilepsy and cortical cytoarchitectonic abnormalities: an attempt at correlating basic mechanisms with anatomoclinical syndromes.
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Biomedical subjects
Publications and source records attributed to E Andermann.
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Gestational folate deficiency has been associated with abnormal growth and development in both experimental animal and human studies and has been postulated as a putative mechanism for the teratogenic effects of antiepileptic drugs (AEDs). Animal studies have shown that the administration of AEDs results in folate depletion and teratogenic effects. Attempts to prevent the teratogenic effects of AEDs by coadministration of folate have shown variable results, perhaps because of a lack of understanding about the specific effects of AEDs on folate metabolism. Our prospective study of women with epilepsy showed that blood folate levels decreased with increasing plasma AED levels and with the number of AEDs. Low blood folate levels before and/or early in pregnancy were significantly associated with spontaneous abortion and the occurrence of developmental anomalies in the offspring. These findings suggest that folate supplementation might be one means of preventing the occurrence of abnormal pregnancy outcome in women with epilepsy, including neural-tube defects in the offspring.
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Multiple symmetrical lipomatosis is a striking clinical finding associated with a variety of peripheral and central nervous system abnormalities. We describe 4 unrelated patients with evidence of mitochondrial dysfunction in skeletal muscle. Multiple symmetrical lipomatosis is an additional, albeit unusual, manifestation of the expanding clinical spectrum of mitochondrial diseases.
We studied 30 patients with partial epilepsy and a radiological or pathological diagnosis of localized neuronal migration disorders, with a view to surgical treatment. Eight patients had identifiable prenatal etiological factors. The frequency of complex partial, partial motor, and secondarily generalized seizures was approximately 70% each. Drop attacks were present in 27%: Their presence usually correlated with a lesion involving the central region. Partial motor or generalized convulsive status epilepticus occurred in 30%, and was most frequently associated with extensive structural abnormalities involving two or more lobes. A full-scale intelligence quotient of less than 80 was found in 44%. Magnetic resonance imaging (MRI) was superior to computed tomography for identification of the dysplastic cortical lesions. In one third, MRI showed only subcortical abnormalities. It did not allow distinction between true pachygyria, focal cortical dysplasia, or the forme fruste of tuberous sclerosis. The epileptogenic area was usually more extensive than the lesion; it was multilobar in more than 70% of patients. Of 26 surgically treated patients, a histological diagnosis of the type of neuronal migration disorder was possible in 22: 12 had focal cortical dysplasia and 10 the forme fruste of tuberous sclerosis. In the remaining 4, no definite histological diagnosis was made, since the maximally abnormal tissue could not be examined. In the latter, and in the 4 nonoperated patients, the diagnosis of neuronal migration disorder was based on imaging findings. The presence of the forme fruste of tuberous sclerosis correlated with delayed psychomotor development and more extensive epileptogenic areas.
Multiple and different genetic defects may be associated with the development of diabetes mellitus. Friedreich's ataxia (FA) is an autosomal recessively inherited neurologic disease associated with a high prevalence of diabetes. We previously demonstrated that patients with FA have insulin resistance prior to the development of overt diabetes mellitus. To determine if insulin resistance is an inherited characteristic in this group, we performed oral glucose tolerance tests (OGTT) on first-degree relatives, 21 parents and 17 siblings, of patients with FA. While fasting concentrations were normal, both glucose and insulin concentrations in response to oral glucose were significantly elevated compared with controls. Corrected insulin responses, CIR = I x 100/G (G-70) (I = insulin, G = glucose), were not different from controls, whereas peripheral insulin activities, A = 10(4)/Ip Gp (p = values of I and G at peak glucose concentration), were significantly decreased (FA, 0.66 +/- 0.11, P less than .001; parents, 0.63 +/- 0.06, P less than .001; siblings, 0.72 +/- 0.09, P less than .01; v controls, 1.52 +/- 0.19), indicating the presence of insulin resistance in patients and first-degree relatives. Multiple discriminant analysis was used to separate patients with FA from controls. The combination of GLUT (sum of glucose values 0 to 3 hours of the OGTT) and CIR achieved significant separation (P less than .0004). Subsequent assignment of the relatives showed that 17 of 18 parents and 11 of 16 siblings (69%) fell in the range of FA, rather than with controls. These data suggest that insulin resistance is an inherited trait in this group.(ABSTRACT TRUNCATED AT 250 WORDS)
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Tuberous sclerosis (TSC) is an autosomal dominant disorder with both neurological and cutaneous manifestations often resulting in significant disability. Although it has been studied clinically and biochemically for many years, the underlying pathophysiology remains unknown. Genetic linkage analysis provides an alternative strategy for understanding the genetic etiology of this disease. Genetic linkage of a gene for TSC to loci in 9q32-9q34 has been reported but has not been a universal finding, since absence of linkage to 9q loci, as well as linkage to loci on 11q, have also been reported. We present here data on 22 families (21 previously unreported) segregating TSC. Our results strongly support a TSC locus in the 9q32-34 region for approximately one-third of families and provide significant evidence for genetic heterogeneity. Application of newly described highly polymorphic dinucleotide repeat marker loci in TSC greatly enhanced the informativeness of our pedigrees and was vital for detecting the heterogeneity. No clear evidence of linkage to chromosome 11q22 markers was found, suggesting that a still unidentified TSC locus elsewhere in the genome may account for the majority of TSC families.
We report two cases of Alzheimer disease (AD)--one of them familial--in which the patient also had amyotrophic lateral sclerosis (ALS), and one patient with familial AD who had a son with ALS. Three further cases of probable ALS were found in pedigrees of AD reported from the literature. It is proposed that this association is not coincidental, but may suggest an etiological factor in common.
Nine patients had reflex activation of seizures by calculation, card and board games, or spatial tasks. The common denominator for these and the 16 others reported in the literature appears to be activity related to function of the parietal lobe. The clinical and EEG findings in all 25 patients support the diagnosis of primary generalized epilepsy. Seizures usually start during adolescence and consist of myoclonus, absences, and generalized convulsions. Specific inquiry about reflex activation should be carried out in patients with generalized epilepsy since this is rarely provided spontaneously. Attacks could be controlled satisfactorily in 89% of our patients. The genetic features are those of a primary generalized epileptic disorder without evidence for a specific inheritance of reflex sensitivity. Neuropsychological analysis of the stimuli points to parietal cortical dysfunction. These stimuli lead to activation of a generalized epileptic process analogous to the occipital cortical participation in the activation of generalized epileptic abnormality occurring in patients with photosensitive epilepsy.
Two Tay-Sachs disease (TSD) patients of French-Canadian origin were shown by Myerowitz and Hogikyan to be homozygous for a 7.6-kb deletion mutation at the 5' end of the hexosaminidase A alpha-subunit gene. In order to determine whether all French-Canadian TSD patients were homozygotes for the deletion allele and to assess the geographic origins of TSD in this population, we ascertained 12 TSD families of French-Canadian origin and screened for occurrence of mutations associated with infantile TSD. DNA samples were obtained from 12 French-Canadian TSD families. Samples were analyzed using polymerase-chain-reaction (PCR) amplification followed by hybridization to allele-specific oligonucleotides (ASO) or by restriction analysis of PCR products. In some cases Southern analysis of genomic DNA was performed. Eighteen of the 22 independently segregating mutant chromosomes in this sample carried the 7.6-kb deletion mutation at the 5' end of the gene. One chromosome carried the 4-nucleotide insertion in exon 11 (a "Jewish" mutation). In this population no individuals were detected who had the substitution at the splice junction of exon 12 previously identified in Ashkenazi Jews. One chromosome carried an undescribed B1 mutation; this allele came from a parent of non-French-Canadian origin. Patients in three families carried TSD alleles different from any of the above mutations. The 5' deletion mutation clusters in persons originating in southeastern Quebec (Gaspé) and adjacent counties of northern New Brunswick.
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Expression of the hexosaminidase isozymes was evaluated in fibroblast cell lines obtained from two sibs of Lebanese-Christian origin who presented with juvenile-onset Tay-Sachs disease. In the normal control fibroblasts the alpha subunit of hexosaminidase A (hex A) is synthesized as a 67 KD precursor which is cleaved in lysosomes to a mature 54 KD peptide. The patients' fibroblasts were capable of synthesizing the 67 KD precursor but failed to convert it to the mature subunit. The alpha subunit precursor synthesized by patients' cells could not be phosphorylated, nor was the patients' alpha subunit precursor secreted into the medium in response to NH4Cl, which caused accumulation of both alpha and beta subunit precursor in the medium of the normal control fibroblasts. The measurement of residual enzyme activity in the fibroblasts of patients which best correlated with the onset of the illness was the ion exchange chromatographic separation of Hex A-associated hydrolysis of the synthetic substrate 4-methylumbelliferyl N-acetyl-beta-D-glucosamine-6-sulfate (4MUGS). The patients had 0.32% and 0.36% of Hex A-associated 4MUGS cleaving activity compared to normal control fibroblasts as compared to less than 0.016% for infantile Tay-Sachs disease fibroblasts. The residual Hex A activity in patients' cells had a pH optimum identical with normal enzyme (pH 3.9-4.0), a reduced specific activity for 4MUGS (relative to hydrolysis of unsulfated synthetic substrate), and a greatly enhanced thermal stability. The occurrence of this form of Tay-Sachs disease in Lebanon, the fact that the condition has been described in three unrelated Lebanese immigrant families in Canada, together with the fact that the grandparents of the unrelated probands come from villages in both the northern and southern regions of Lebanon, leads us to speculate that a gene causing juvenile-onset Tay-Sachs disease may not be infrequent in Lebanon.
In patients with an acceptable pathological diagnosis of Kufs disease, two major forms have been identified: Type A presenting as progressive myoclonus epilepsy around the age of 30, and Type B presenting in the same age range with dementia as well as cerebellar and/or extra-pyramidal signs. In adolescence, two subgroups of neuronal ceroid-lipofuscinosis (NCL) emerge. The first group consists of patients resembling either type A or B Kufs disease, but with earlier onset (20% of all cases). These must be distinguished from the second group of rare patients with protracted juvenile NCL presenting with early and prominent visual failure. Although Kufs disease is rare, diagnosis during life should now be possible. The advantages, techniques, and pitfalls of biopsy diagnosis are presented by Carpenter et al. [1988]. We believe that delineation of these two clinical syndromes should aid in the identification of other possible cases of Kufs disease, leading to appropriate pathological examinations to confirm the diagnosis. Knowledge of whether this clinical distinction is biologically meaningful must await the discovery of the more fundamental biochemical defects.
We have found a group of individuals with the late infantile, the early juvenile variant, and juvenile neuronal ceroid-lipofuscinosis (NCL) in Newfoundland, an island with a population of 500,000. In the past 25 yr, we have ascertained 44 cases of NCL in 32 sibships: 32 cases of late infantile NCL (LINCL) in 24 sibships, 11 cases of the early juvenile variant in 7 sibships, and one patient with the juvenile form (JNCL). The clinical presentation of the LINCL patients is very characteristic, with onset of seizures at age 2 1/2 to 3 1/2 yr, frequently with drop attacks and myoclonic jerks, followed by mental deterioration, ataxia, visual loss, and death by the end of the first decade. Typical curvilinear profiles are seen on electron microscopy (EM). The second group of patients mainly have the early juvenile variant with onset of seizures at age 5 to 6 yr and fingerprint profiles with occasional curvilinear profiles on EM. However, a child with the juvenile form presenting with blindness was also encountered. In both of these types, death occurs in the second decade of life. There is no overlap of these three clinical forms within sibships, although both late infantile and early juvenile variant types may occur in the same small fishing village. All three forms appear to be inherited as autosomal recessive traits. Although the early juvenile variant has been postulated to represent a double heterozygote between LINCL and JNCL, this cannot be confirmed on the basis of the present study.(ABSTRACT TRUNCATED AT 250 WORDS)