Segregation analysis of Alzheimer pedigrees: rare Mendelian dominant mutation(s) explain a minority of early-onset cases. French Alzheimer Collaborative Group

Segregation analysis of Alzheimer disease (AD) in 92 families ascertained through early-onset ( < or = age 60 years) AD (EOAD) probands has been carried out, allowing for a mixture in AD inheritance among probands. The goal was to quantify the proportion of probands that could be explained by autosomal inheritance of a rare disease allele "a" at a Mendelian dominant gene (MDG). Our data provide strong evidence for a mixture of two distributions; AD transmission is fully explained by MDG inheritance in < 20% of probands. Male and female age-of-onset distributions are significantly different for "AA" but not for "aA" subjects. For "aA" subjects the estimated penetrance value was close to 1 by age 60. For "AA" subjects, it reaches, by age 90, 10% (males) and 30% (females). We show a clear cutoff in the posterior probability of being an MDG case.

[Saccadic latencies and unilateral spatial neglect caused by parietal lesions]

Latencies of lateral visually guided saccades were studied in 12 right handed patients who had unilateral ischaemic lesions involving the parietal lobe. The patients were divided into two groups according to the right or left side of the lesions. The severity of unilateral spatial neglect was assessed. In right parietal lesions, the asymmetry of latencies was related to the presence of unilateral spatial neglect and correlated with ist severity. According to the stimulus condition used, we suggest that the asymmetry of latency is explained in terms of an inability to disengage.

Evidence for apolipoprotein E epsilon 4 association in early-onset Alzheimer's patients with late-onset relatives

Recently several reports have extended the apolipoprotein E (APOE) epsilon 4 association found in late-onset Alzheimer's disease (LOAD) patients to early-onset (EO) AD patients. We have studied this question in a large population of 119 EOAD patients (onset < or = 60 years) in which family history was carefully assessed and in 109 controls. We show that the APOE epsilon 4 allele frequency is increased only in the subset of patients who belong to families where LOAD secondary cases are present. Our sampling scheme permits us to demonstrate that for an individual, bearing at least one epsilon 4 allele increases both the risk of AD before age 60 and the probability of belonging to a family with late-onset affected subjects. Our results suggest that a subset of EOAD cases shares a common determinism with LOAD cases.

[Phenotype of familial forms of early-onset Alzheimer's disease linked to chromosome 14. Clinical and neuropsychological characteristics of a large group]

We report the clinical features and neuropsychological data of chromosome-14 linked early-onset Alzheimer's disease in a large family (FAD-RO1). Information available in the literature from eight additional chromosome 14-linked Alzheimer's disease kindreds was compared with the data obtained from six kindreds with amyloid precursor protein gene mutations (APP). In the chromosome 14-linked families the disease has an earlier onset and a shorter duration than in families with APP mutations, with an age at death lower than sixty years of age. Seizures, myoclonus and extra pyramidal signs were frequently present in the cases of FAD-RO1 as in six chromosome 14-linked kindreds, but these features were absent in two other ones. The high frequency of seizures (> 80%) in FAD-RO1 and two other chromosome 14-linked kindreds is remarkable. Seizures and myoclonus were encountered at a lower prevalence in APP kindreds. This review suggests that some clinical features are more prevalent in chromosome 14-linked than in APP kindreds but a phenotypic heterogeneity does exist within and between families. The profile of deterioration of the neuropsychological performances, as illustrated by the FAD-RO1 members, shows that chromosome 14-linked kindreds do not demonstrate a specific expression in comparison to APP kindreds. Memory was first impaired. Deficits in visuo-spatial and visuopractic abilities were then noted. Finally the verbal performance deteriorated.

Mutations of the presenilin I gene in families with early-onset Alzheimer's disease

We analyzed 12 families with autosomal dominant early-onset Alzheimer' s disease (EOAD)for mutations in the coding region of the presenilin I (PSNLI) gene corresponding to the AD3 locus on chromosome 14q24.3. A total of eight missense mutations at codons 82, 115, 139, 163, 231, 264, 392, and 410 including six novel mutations, were identified in eight families. Cosegregation of the mutations with EOAD was confirmed in three families, one including 36 affected individuals. This study underlines the great allelic heterogeneity and the large distribution of the mutations within the PSNLI coding region. Our results support the notion that PSNLI is the major gene involved in autosomal dominant EOAD.

Causes of morbidity and mortality after ruptured aneurysm surgery in a series of 230 patients. The importance of control angiography

BACKGROUND AND PURPOSE

The purpose of this study was to determine the causes of morbidity and mortality after surgery for ruptured aneurysms.

METHODS

Two hundred thirty consecutive patients were studied. Initial hemorrhage volume and vasospasm were evaluated preoperatively with CT, transcranial Doppler ultrasonography, and angiography. Nimodipine infusion was started before surgery. Preoperative clinical status was evaluated according to Hunt and Hess grading criteria. Surgery was performed early in 186 patients (81%). Control angiography, transcranial Doppler ultrasonography, and CT were performed routinely after surgery. Hypodense areas revealed by control CT were related to intracerebral initial hematoma, vasospasm, postoperative thrombosis, or spatula hyperpressure.

RESULTS

Clinical outcome was excellent or good (Glasgow Outcome Scale [GOS] scores of 1 or 2) in 176 patients (77%), 17 (7%) were disabled (GOS score of 3), and 37 (16%) were vegetative or dead. In patients in good condition (grades I to III) preoperatively (n = 200), 38 had an unfavorable outcome (GOS score of 2, 3, 4, or 5). The major cause of complication was postoperative thrombosis (42%). In patients in poor condition (grade IV or V) (n = 30), 27 had an unfavorable outcome. The major cause of complication was initial bleeding (66%). Vasospasm was responsible for delayed ischemic deficit in 9 patients (3.9% of the total population).

CONCLUSIONS

Systematic angiography remains by far the best means for determining the cause of a poor postoperative course.

Calculation and number processing in mild Alzheimer's disease

Calculation and number processing abilities in 17 patients suffering from a mild form of dementia of Alzheimer's type (DAT) were studied by means of a standardized multitask assessment battery, the EC301 (Deloche et al., 1994). Patients were selected from a larger sample by using a specific visuo-perceptive task to control the confounding effects of deficits in analysing digit serial order. Language and memory skills were evaluated by means of standardized testing procedures. The EC301 overall score showed impaired performance in 12 cases. Calculation and number processing scores were highly correlated with Mini-Mental State Examination and language performance. However, multiple single-case analyses indicated heterogeneous patterns of preserved/impaired abilities with respect to the three cognitive areas under investigation (calculation, memory, and language) and to the different components of the calculation and number processing system.

Characteristics of familial aggregation in early-onset Alzheimer's disease: evidence of subgroups

Characteristics of familial aggregation of Alzheimer's Disease were studied in 92 families ascertained through a clinically diagnosed proband with an onset below age 60 years. In each family data were systematically collected on the sibships of the proband, of his father, and of his mother. A total of 926 relatives were included and 81% of the living relatives (i.e., 251 individuals) were directly examined. The estimated cumulative risk among first degree relatives was equal to 35% by age 89 years (95% confidence interval 22 to 47%). This result does not support the hypothesis that an autosomal dominant gene, fully penetrant by age 90 years, is segregating within all these pedigrees. Despite the fact that all probands were selected for an onset before age 60 years it was shown that two types of families could be delineated with respect to age at onset among affected relatives: all secondary cases with an onset below age 60 years were contributed by a particular group of families (type 1 families), whereas all secondary cases with an onset after age 60 years were contributed by another group of families (type 2 families). Although genetic interpretation of these findings is not straightforward, they support the hypothesis of etiologic heterogeneity in the determination of early-onset Alzheimer's disease.

The NACP/synuclein gene: chromosomal assignment and screening for alterations in Alzheimer disease

The major component of the vascular and plaque amyloid deposits in Alzheimer disease is the amyloid beta peptide (A beta). A second intrinsic component of amyloid, the NAC (non-A beta component of amyloid) peptide, has recently been identified, and its precursor protein was named NACP. A computer homology search allowed us to establish that the human NACP gene was homologous to the rat synuclein gene. We mapped the NACP/synuclein gene to chromosome 4 and cloned three alternatively spliced transcripts in lymphocytes derived from a normal subject. We analyzed by RT-PCR and direct sequencing the entire coding region of the NACP/synuclein gene in a group of patients with familial early onset Alzheimer disease. No mutation was found in 26 unrelated patients. Further studies are required to investigate the implication of the NACP/synuclein gene in Alzheimer disease.

[Palinacousis with hemianacusia caused by left temporal lesion]

Palinacousis (auditory perseveration) is reported in a 78-year-old patient with a left temporo parietal astrocytoma. The patient complained of "echoing voice" in his right ear. Palinacousis was associated with sensitive partial seizures. Neuropsychological investigations revealed hemianacusia with normal performance for phonological discrimination and verbal repetition. We suggest that these preserved abilities allowed emergence of palinacousis.

[Late neurologic complications of galactosemia: study of 3 cases]

Galactosemia is an autosomal recessive, inborn error of galactose metabolism due to the deficiency of galactose-I-phosphate uridyl transferase. Late-onset neurologic complications may develop despite Galactose restriction. Three adult patients are reported. They suffered from mental retardation. Two of them developed progressive cerebellar ataxia, spastic gait and postural tremor. The magnetic resonance imaging revealed moderate cortical atrophy, multifocal areas of increased signal in the periventricular white matter on T2-weighted images, and in one case, abnormal myelination. The Fluoro-2-deoxy-D-glucose position emission tomography showed different patterns of regional hypometabolism.

A large pedigree with early-onset Alzheimer's disease: clinical, neuropathologic, and genetic characterization

We present clinical, neuropsychological, and neuropathologic data on a large pedigree including 34 subjects with early-onset progressive dementia. The mean (+/- SD) age at onset was 46 +/- 3.5 years and the mean age at death 52.6 +/- 5.7 years. Twelve patients were clinically diagnosed as having probable Alzheimer's disease (AD) according to the NINCDS-ADRDA criteria. Neuropsychological evaluation, performed at a moderate stage of the disease, was available in six subjects and showed a classic pattern of cognitive deficit. Myoclonus and extrapyramidal signs were common, and seizures were present in all affected subjects. There were neuropathologic changes typical of AD in two brains. A significant lod score of 5.48 was observed at a recombination fraction of theta = 0.0 with the genetic marker D14S43, thereby establishing that the responsible gene was located on chromosome 14q24.3. These results suggest that epilepsy could represent a particular feature in AD families linked to chromosome 14q.

[Intermittent sea-saw nystagmus successfully treated with clonazepam]

See-saw nystagmus is a pendular nystagmus with two distinct components: a conjugate torsional component and a disjonctive vertical component. The acquired form of nystagmus is usually seen with parasellar mass and less frequently in head injury or brainstem infarction. Almost all patients with parasellar mass or head injury have associated bitemporal hemianopia. We report the case of a 27-year-old man who developed intermittent daily oscillopsia five years after a severe head injury. On neurological examination, the patient showed a congenital left eye divergence with left eye convergence paresis, an anosmia, a right optic atrophy and a bitemporal hemianopia. Visual acuity was 7/10 and 3/10 for the right and left eyes. The rest of the neurological examination was unremarkable. Electroencephalogram during oscillopsia was normal. MRI revealed bilateral orbito-frontal low signal intensity on T1 weighted images. The brainstem, the diencephalon and the ventricular system appeared to be intact. Eye movement recordings exhibited intermittent see-saw nystagmus. Clonazepam treatment resolved the see-saw nystagmus. Slowly withdrawal of clonazepam was done without return of the see-saw nystagmus.

Midsagittal MR measurements of the corpus callosum in healthy subjects and diseased patients: a prospective survey

PURPOSE

To determine quantitatively a possible corpus callosum (CC) involvement in normal aging and white matter diseases.

METHODS

Midsagittal size and signal of CC were recorded prospectively from 243 routine MR brain examinations. A midline internal skull surface (MISS) and subcutaneous fat signal intensity were measured to calculate CC/MISS and CC/fat ratios. Four groups of subjects were studied: 124 apparently healthy subjects, 45 patients with multiple sclerosis, 13 patients with a noncerebral cancer under chemotherapy, and 37 AIDS patients.

RESULTS

Mean surface area of CC in controls was 6.36 cm2. It was significantly larger in men than in women (P < .05), but CC/MISS ratio was not. Elderly controls > 70 years and AIDS patients displayed significant CC atrophy, as well as multiple sclerosis subjects with long-standing disease or with a severe chronic progressive form.

CONCLUSION

CC substance loss identification should not be based on visual inspection or on absolute area, but by means of a CC/MISS ratio.

Anorectal manometric anomalies in seven patients with frontal lobe brain damage

We studied the anorectal manometric and urodynamic pattern of seven patients who had right and/or left frontal lobe injury to investigate the possibility that the frontal lobe area plays an important role in control of anorectal motility as it does for the urinary bladder. We found that the disturbances of anorectal manometric recordings were similar to those of urodynamic recordings: (1) lack of urinary bladder filling sensation (two cases), increased perception threshold of rectal distension (two cases); (2) uninhibited detrusor contractions during filling (five cases), spontaneous rectal contractions during the resting step (four cases); (3) absence of micturition (one case), absence of rectoanal inhibitory reflex (one case). Furthermore, in all but one patient, we observed a decrease in the amplitude and duration of the voluntary contraction of the anal canal (six cases). However, in two of the seven patients we found hypertonia in the anal canal (upper part: one case, lower part: one case), but never in the urethral canal. Our results suggest that frontal lobe may be involved in the nervous control of anorectal motility as it is for urinary bladder function. However, the lack of correlation between urinary and anorectal anomalies in individual cases suggests that these functions depend on distinct areas of the frontal lobe.

[Development of a model to study the anti-edema properties of Ginkgo biloba extract]

The vasogenic edema observed after irradiation of the brain constitutes a new and interesting model to study the anti-oedema properties of drugs. We have just completed a first pharmaco-clinical study of Ginkgo biloba extract with the dual purpose of assessing the feasibility of a therapeutic protocol and of deciding on simple and non-invasive criteria that would quantity cerebral oedema. The results of this pilot study have encouraged us to pursue our investigations under strict methodological conditions, in view of their therapeutic but also epidemiological interest.

[Cervico-occipital injury and bilateral paralysis of cranial nerve XII. Apropos of a case]

A patient with bilateral traumatic hypoglossal palsy is presented. Evaluation of the atlanto-occipital articulation is difficult. Prompt radiographic diagnosis of this injury can be made by computed tomography. In this case, there was bony avulsion of the alar ligament from the occipital condyle. We suggest a severe blow to the head in a lateral direction.