[Prevalence of pervasive developmental disorders. A review]. / Sur la prévalence de l'autisme et des troubles envahissants du développement (TED).

INTRODUCTION: Estimates of the prevalence of autism and pervasive developmental disorders (PDD) are discordant and are moving towards an apparent increase in rates. LITERATURE REVIEW: The studies carried out since 1966 illustrate the variability of the protocols used and explanatory hypotheses put forward. These investigations are difficult, sparse, but still growing at the same time that a debate develops on the possible increase in actual prevalence. Indeed, the rate initially admitted for classic autism was 5/10,000, then 1/1000 with an expanded definition to the forms, but the current figures are very different (almost 0.7% for all PDD), and this increase raises questions. The arguments in favour of an apparent increase are primarily methodological. Several biases are encountered when one compares the recent publications with those of previous years. First, autism is better known and recognized than 30 or 40 years ago. Then, the diagnostic criteria used over time are changing variables, and comparisons difficult. Recent studies using the criteria of a broader definition of autism, polyhandicap with severe retardation and autism signs of lighter forms. The fact that children with autism are diagnosed more frequently in the younger age could also occasionally lead to an artificial increase in the number of cases identified in new surveys in populations of young children. Other factors are cited to explain the current increase. There could be higher rates of autism (and mental retardation) among children of migrants from distant countries, with the aetiological hypothesis of maternal infections, more frequent due to immune deficiency against infectious agents depending on the environment, metabolic decompensations also related to changes in surroundings, or more births from unions among migrant mothers and men with Asperger syndrome (with increased risk of paternity of a child with autism). Other theories relate to pollution, vaccinations, a growing number of premature babies; all assumptions that appear, for the time being, insufficiently explored and documented. The issue is also one of the motivations underlying these steps, and setting a parallel prevalence actually increased with this or that factor has presently been scientifically validated. Finally, if a careful reading of recent publications indicates that autism has become more frequent; assumptions that describe an increase in "artificial", based on methodological arguments, seem to be more consistent. EFFECTS OF EXTENSION OF DIAGNOSTIC CRITERIA AND NOSOGRAPHY FOR PDD: Today, the recruitment of individuals with autism in a population far exceeds the initial criteria of Kanner in the 1970's. It includes clinical forms with associated pathologies, or lighter and probably more frequent clinical forms. Other assumptions arouse interest, but also controversy regarding their relevance. The enumeration of cases of PDD in a population is actually at its beginning. In the 1970's, "childhood psychoses" (the term then used) seemed rare. The identification of cases was probably the main reason. Long available figures remain scarce, and their rate increases gradually from the 1990s, but is, in fact, a problem of inflation. What is the part played in this flight of changing diagnostic criteria and substitutions, or other methodological effects? Or even opportunistic effects, if we speak of an epidemic to undermine a variety of factors. The evidence provided so far is the improved identification of cases, enlargement of the concept, and better shared diagnostic criteria. However, the validity and limitations of clinical forms are still vague and unresolved. DISCUSSION: How to study epidemiology in the future - to move forward, studies should be designed with partners' medical history and medicosocial studies, based on a better consensual methodology, epidemiology, statistics and diagnosis, with a definition of the thresholds for inclusion, and arbitration procedures. On this basis, a study must also be coordinated with those concerning mental retardation, learning disorders, etc, otherwise the same topics will be counted twice or even three times. As for the addition of syndromic forms of PDD (those with known aetiology), their number is still below a proportion sufficient to be an appeal. Moreover, another problem exists: the degree of membership of each of these syndromes, or individual cases, or autistic spectrum disorders (internal variability phenotypes). For the moment, we could design two studies included better: developmental disorders and associated pathologies. Regarding the "ethic" dimension, a more regular diagnosis of PDD (preferred to that of mental retardation or learning disorder) will lead to shared practices and set limits for greater recognition.

MPTP intoxication in mice: a useful model of Leigh syndrome to study mitochondrial diseases in childhood.

The basal ganglia, which are interconnected in the striato-nigral dopaminergic network, are affected in several childhood diseases including Leigh syndrome (LS). LS is the most common mitochondrial disorder affecting children and usually arise from inhibition of the respiratory chain. This vulnerability is attributed to a particular susceptibility to energetic stress, with mitochondrial inhibition as a common pathogenic pathway. In this study we developed a LS model for neuroprotection trials in mice by using the complex I inhibitor MPTP. We first verified that MPTP significantly inhibits the mitochondrial complex I in the brain (p = 0.018). This model also reproduced the biochemical and pathological features of LS: MPTP increased plasmatic lactate levels (p = 0.023) and triggered basal ganglia degeneration, as evaluated through dopamine transporter (DAT) autoradiography, tyrosine hydroxylase (TH) immunohistochemistry, and dopamine dosage. Striatal DAT levels were markedly decreased after MPTP treatment (p = 0.003). TH immunoreactivity was reduced in the striatum and substantia nigra (p = 0.005), and striatal dopamine was significantly reduced (p < 0.01). Taken together, these results confirm that acute MPTP intoxication in young mice provides a reproducible pharmacological paradigm of LS, thus opening new avenues for neuroprotection research.

Spectrum of SCN1A gene mutations associated with Dravet syndrome: analysis of 333 patients.

INTRODUCTION: Mutations in the voltage-gated sodium channel SCN1A gene are the main genetic cause of Dravet syndrome (previously called severe myoclonic epilepsy of infancy or SMEI). OBJECTIVE: To characterise in more detail the mutation spectrum associated with Dravet syndrome. METHODS: A large series of 333 patients was screened using both direct sequencing and multiplex ligation-dependent probe amplification (MLPA). Non-coding regions of the gene that are usually not investigated were also screened. RESULTS: SCN1A point mutations were identified in 228 patients, 161 of which had not been previously reported. Missense mutations, either (1) altering a highly conserved amino acid of the protein, (2) transforming this conserved residue into a chemically dissimilar amino acid and/or (3) belonging to ion-transport sequences, were the most common mutation type. MLPA analysis of the 105 patients without point mutation detected a heterozygous microrearrangement of SCN1A in 14 additional patients; 8 were private, partial deletions and six corresponded to whole gene deletions, 0.15-2.9 Mb in size, deleting nearby genes. Finally, mutations in exon 5N and in untranslated regions of the SCN1A gene that were conserved during evolution were excluded in the remaining negative patients. CONCLUSION: These findings widely expand the SCN1A mutation spectrum identified and highlight the importance of screening the coding regions with both direct sequencing and a quantitative method. This mutation spectrum, including whole gene deletions, argues in favour of haploinsufficiency as the main mechanism responsible for Dravet syndrome.

[Neurofibromatosis type 1 complications in the pediatric age: follow-up of a hundred cases]. / Complications de la neurofibromatose de type 1 chez l'enfant: à propos d'une série de 100 cas.

UNLABELLED: Neurofibromatosis 1 (NF1) is a frequent genetic disease. Diagnostic criterias were established in 1988. The patients can exhibit various and unpredictable complications. OBJECTIVES: To check the efficiency of a coordinated follow-up in specialized multidisciplinary centers providing a higher quality of management and to have a better knowledge of the complications including their true frequencies. POPULATION AND METHODS: We report a serie of 100 NF1 children who were followed-up during 4 years in a specialized center at the Tours University Hospital. Three hospital check-up at 2-5, 6-7, 14-15 years of age were performed as well as an annual physical examination. RESULTS: In our serie, the mean age was 7.8 years old with a sex ratio of 1. The mean age at diagnosis was 3.8 years old and the main diagnosis criteria were the café-au-lait spots and the family history for 80% of the patients. The optic nerve glioma has a low frequency of 5%. Learning disabilities clearly represent the most frequent complication (46% of the patients). CONCLUSION: An early detection of these difficulties is a priority for the appropriate management of these children.