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M Leboyer

Publications and source records attributed to M Leboyer.

At least 73 records · Page 4Linked to original sources
PubMed1994

Is Rett syndrome a chromosome breakage syndrome?

Lymphocytes from venous blood from 15 girls with Rett syndrome (RTS), 7 girls with RTS "forme fruste," and 46 unrelated control females were examined. All subjects had a normal karyotype using RHG and RTBG technique. The frequency of gaps and breaks was determined for each group. A significantly higher (P < 0.01) frequency of chromosome breakage was observed in RTS subjects compared to controls. This work suggests that an increased tendency to chromosome breakage may be part of a genetically determined disorder in RTS patients.

Case-Control Studies↗
PubMed1994

Failure to find evidence for linkage or association between the dopamine D3 receptor gene and schizophrenia.

OBJECTIVE: This study was performed to assess the possible involvement of the dopamine D3 receptor gene (DRD3) in the etiology of schizophrenia. The authors' approach included a population study and a family study using both parametric (lod score) and nonparametric (affected pedigree member) methods of linkage analysis. METHOD: Two different DNA markers were studied at the DRD3 locus. The family study included 35 multiplex families of schizophrenic subjects for the linkage analyses. The population study involved 50 unrelated schizophrenic subjects and 50 normal comparison subjects from the same ethnic and geographic origin. RESULTS: Whichever clinical classification was used to define the pathological phenotype (schizophrenia or schizophrenia spectrum), the results of the lod score and affected pedigree member studies did not provide any evidence of linkage of the DRD3 gene to the illness. The negative results of the association study reinforce these results. CONCLUSIONS: The hypothesis that the DRD3 gene has a predisposing role in schizophrenia was not supported by these population and family studies. However, the possibility that this gene has a role in the etiology of the disease cannot be definitely excluded because of the intrinsic limitations of the methods of analysis and the number of subjects studied.

Alleles↗
PubMed1994

Difference between plasma N- and C-terminally directed beta-endorphin immunoreactivity in infantile autism.

OBJECTIVE: The authors investigated whether there is excessive opioid activity in infantile autism by measuring plasma beta-endorphin in patients with autism compared with patients who had Rett's syndrome and normal comparison subjects. METHODS: Radioimmunoassays for beta-endorphin using C-terminally and N-terminally directed antisera were applied to plasma samples from 67 children who met both DSM-III-R and ICD-10 diagnostic criteria for infantile autism, 22 girls with Rett's syndrome, and 67 normal children matched in age and sex with the children with autism. RESULTS: Median N-terminally directed beta-endorphin immunoreactivity appeared to be slightly lower in subjects with autism (7 pg/ml) and clearly higher in the girls with Rett's syndrome (40 pg/ml) than in the comparison subjects (9 pg/ml). Median C-terminally directed beta-endorphin immunoreactivity was higher in the girls with Rett's syndrome (35 pg/ml) and much higher in patients with autism (70 pg/ml) than in comparison subjects (8 pg/ml). CONCLUSIONS: These findings demonstrate the existence of a wide discrepancy between C- and N-terminally directed beta-endorphin immunoreactivity among children with autism. Despite the fact that the nature of the antigen recognized in the plasma of autistic children by the C-terminally directed anti-beta-endorphin serum remains to be characterized, the difference between C- and N-terminally directed beta-endorphin immunoreactivity might suggest an abnormal processing of the pro-opiomelanocortin gene in infantile autism.

Adolescent↗
PubMed1993

A SCAN-SADS comparison study of psychotic subjects and their first-degree relatives.

Two diagnostic interviews, the Schedule for Affective Disorders and Schizophrenia (lifetime version) (SADS-LA) and the Schedule for the Clinical Assessment of Neuropsychiatry (SCAN) were compared for main diagnoses and for their acceptibility to psychotic subjects and their psychiatrically well relatives. Broad agreement for DSM-III, DSM-III-R and draft ICD-10 diagnoses was good, although there were areas of disagreement between the two interviews which are discussed.

Adolescent↗
PubMed1993

Possible association of c-Harvey-Ras-1 (HRAS-1) marker with autism.

We tested for an association between autism and genes coding for enzymes involved in monoaminergic metabolism and for a linked marker, c-Harvey-Ras-1 (HRAS 1), using restriction fragment length polymorphisms. We did not find evidence of an association between autism and genes coding for tyrosine hydroxylase, dopamine-beta-hydroxylase (DBH), and tryptophan hydroxylase. However, we report a positive association between autism and the locus containing the gene for HRAS-1.

Adolescent↗
PubMed1992

Confirmation of linkage of benign familial neonatal convulsions to D20S19 and D20S20.

Benign familial neonatal convulsions (BFNC) is an idiopathic form of epilepsy beginning within the first six months of life. Its genetic origin and autosomal dominant mode of inheritance have been suspected since its first description. Recently, the BFNC gene has been localised within chromosome 20q in one large pedigree. For the first time, we confirm here (with D20S19 and D20S20) the close linkage of BFNC to chromosome 20q in six French pedigrees. In addition, the existence in these families of several cases of febrile convulsions (FC), another epileptic syndrome with an autosomal dominant genetic component, led us to study the possibility of a genetic background identical to BFNC. Our results suggest the existence of different susceptibility genes for BFNC and FC.

Blotting, Southern↗
PubMed1992

Failure to replicate linkage between chromosome 5q11-q13 markers and schizophrenia in 28 families.

Sherrington et al. (1988) reported linkage between markers located on the 5q11-q13 region of chromosome 5 and schizophrenia in five Icelandic and two British families. To date, however, all attempts to replicate the initial finding have failed. Using three markers of chromosome 5, we have studied 28 additional French pedigrees. When our data were analyzed both with parametric (i.e., lod scores) and nonparametric methods, we found no evidence of linkage. Thus, we were unable to replicate the earlier report by Sherrington et al.

Chromosomes, Human, Pair 5↗
PubMed1992

Relationship of HLA to schizophrenia not supported in multiplex families.

The role of the human histocompatibility complex (HLA) in the pathogenesis of schizophrenia has been suggested in previous reports. We conducted a genetic study in 33 new families. Our linkage analysis, which used the affected sib-pair method, did not provide evidence for nonrandom assortment. Moreover, the results of an association study using the "haplotype relative risk" method failed to confirm the positive association between HLA A9 and schizophrenia. Taken together, our data did not support any relationship of HLA type to schizophrenia.

Genetic Linkage↗
PubMed1992

Clinical subtypes and age at onset in schizophrenic siblings.

This study examines the concordance of clinical subtypes and age at onset of schizophrenia in 42 sibships of multiply affected schizophrenic patients. Subtypes were defined by four major diagnostic systems (DSM-III, DSM-III-R, ICD-10, and Tsuang-Winokur criteria) and rated both for the first hospitalization and long-term diagnosis. When a sibship method was used, no concordance for subtypes was found in siblings. Age at onset, analyzed as a continuous variable with the intraclass correlation method, was found to be correlated in siblings. This finding suggest that the search for continuous traits distributed in families of schizophrenic patients might constitute an alternative to discrete category-based family studies.

Age Factors↗
PubMed1992

Evidence for a pseudoautosomal locus for schizophrenia. I: A replication study using phenotype analysis.

A locus for schizophrenia within the pseudoautosomal region of chromosomes X and Y has been suggested by Crow on the basis of epidemiological data. The present report replicates this finding in a sample of 38 French multiply affected families with schizophrenia. Sibship and pairwise analysis, with or without weighted-pair correction, with three different systems of family classifications, showed there to be an excess of same-sex pairs in paternally derived sibships, as predicted by the pseudoautosomal hypothesis.

Female↗
PubMed1992

Evidence for a pseudoautosomal locus for schizophrenia. II: Replication of a non-random segregation of alleles at the DXYS14 locus.

Because of an association between sexual aneuploidies and schizophrenia, and because schizophrenic siblings have been found to be more often of the same than of the opposite sex, the susceptibility locus for schizophrenia is thought to lie within the pseudoautosomal region of the sex chromosomes. We analysed 33 sibships comprising 18 pairs, 13 trios, and 2 quartets of affected siblings, and found support for non-random segregation of of alleles at the DXYS14 locus in affected siblings. These findings are consistent with the pseudoautosomal hypothesis for schizophrenia and favour a genetic linkage between DXYS14 and the disease.

Alleles↗
PubMed1992

Naltrexone open trial with a 5-year-old-boy. A social rebound reaction.

The neurobiological rationale for an opiate antagonist pharmacotherapy of autism is presented. Naltrexone efficacy in decreasing autistic behaviour and in increasing social-affiliative behaviour was explored in a 5-year-old autistic boy. Naltrexone (0.5 mg/kg 3 times peer week) was effective in immediately decreasing gross motor activity and stereotyped behaviour and caused a delayed increase of crying, smiling and rough-and-tumble play. This single case presents preliminary evidence that a therapeutically valuable rebound reaction is possible and that the human opioid system modulates social-affective processes. The possibility of psychological factors being instrumental in achieving this effect is discussed as being suitable for future clinical trials.

Attention Deficit Disorder with Hyperactivity↗