Maladie du sirop d'érable
285083
30685349
2008-06-16T04:43:23Z
Chicobot
211899
robot Ajoute: [[ja:メープルシロップ尿症]]
{{Maladie génétique|Nom de la maladie=Maladie du sirop d'érable
|MIM=[http://www3.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=248600 248600]
|Transmission=[[Transmission autosomique récessive|Récessive]]
|Gène=[[BCKDHA (Gène)|BCKDHA]]-[[BCKDHB (Gène)|BCKDHB]]<br>[[DBT (Gène)|DBT]]-[[GCSL (Gène)|GCSL]]
|Monogénique=?
|Empreinte=?
|Chromosome=[[Chromosome 19 humain|19q13.1-q13.2]]-[[Chromosome 6 humain|6p22-p21]]<br>[[Chromosome 1 humain|1p31]]-[[Chromosome 7 humain|7q31-q32]]
|Locus=
|Mutation=Ponctuelle
|Allèle=Plus de 300
|Incidence=1 enfant sur 185 000
|Prévalence=?
|Pénétrance=?
|Nombre=?
|Anticipation=?
|Maladie liée=Aucune
|Prénatal=Possible
|Novo=?
|Porteur=?
|Article=-
}}
La '''maladie du sirop d'érable''' est une [[maladie génétique]] congénitale dans laquelle le corps est incapable de traiter correctement certains [[acide aminé|acides aminés]] .
Chez les enfants non traités, cette maladie se manifeste dès le premier jours par une odeur typique de [[sirop d'érable]] dans le [[cérumen]]. Le passage des acides aminés non métabolisés dans l'[[urine]] et lui conférant aussi une odeur typique de [[sirop d'érable]] ne survient qu' au bout de plusieurs jours.
Les autres signes sont une diminution de l'alimentation en 2 à 3 jours, une apparition d'un encéphalopathie entrainant une léthargie, un opisthotonos, des troubles respiratoires et des mouvements d' "escrime" ou de "bicyclette" vers 4 à 5 jours, puis un coma et des arrêts respiratoires entre 7 à 10 jours.
==Autres noms==
*Leucinose
*Déficit en céto-acide décarboxylase
==Étiologie==
* Mutation des [[gène]]s '''BCKDHA''' et '''MSUD1''' situé sur le [[chromosome]] [[chromosome 19 humain|19]]
* Mutation des [[gène]]s '''DLD''', '''LAD''' et '''PHE3''' situés sur le [[chromosome]] [[chromosome 7 humain|7]]
* Ces gènes produisent des protéines qui agissent de concert en tant que complexe de la déshydrogenase des alpha-céto-acides ramifiés. Ce complexe est essentiel pour détruire la [[leucine]], l'[[isoleucine]] et la [[valine]], trois acides aminés présents dans diverses sortes d'aliments (en particulier les aliments riches en protéines, comme le lait, la viande et les œufs). Des mutations dans l'un ou l'autre de ces gènes réduisent ou éliminent le foctionnement de ce complexe d'enzymes, et empêchent ainsi la destruction normale de la leucine, de l'isoleucine et de la valine. Dès lors, ces acides aminés et leurs produits secondaires s'accumulent dans l'organisme. Vu que de hauts taux de ces substances sont toxiques par rapport au [[cerveau]] et d'autres organes, cette accumulation entraîne de sérieux problèmes médicaux associés à la maladie du sirop d'érable.
==Symptômes==
<!--From early infancy, the condition is characterized by poor feeding, vomiting, lack of energy (lethargy), seizures, and mental retardation. The urine of affected infants has a distinctive sweet odor, much like burned caramel, that gives the condition its name. Maple syrup urine disease can be life-threatening if left untreated.
Maple syrup urine disease can be classified by its pattern of signs and symptoms or by its genetic cause. The most common and most severe form of the disease is the classic type, which appears soon after birth. Variant forms of the disorder appear later in infancy or childhood and are typically less severe, but still involve [[mental retardation|mental]] and physical retardation if not treated.
There are several variations of the disease:
*Classic Severe MSUD
*Intermediate MSUD
*Intermittent MSUD
*Thiamine-responsive MSUD
*E3-Deficient MSUD with Lactic Acidosis
*Fenugreek Tea-->
==Diagnostic==
Le diagnostic repose sur l'élévation plasmatique et urinaire de [[leucine]], [[isoleucine]] et [[valine]], avec présence d'alloisoleucine, parfois notée seulement au cours des accès dans les formes intermittentes
==Sources==
* {{en}} National Library of Medicine. [http://ghr.nlm.nih.gov/condition=maplesyrupurinedisease Genetics Home Reference, Maple syrup urine disease]
* {{fr}} [http://www.orpha.net/ Site en français de renseignement sur les maladies rares et les médicaments orphelins]
* {{en}} Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number:248600[http://www3.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=248600]]
* {{en}} Kevin A Strauss, Erik G Puffenberger, D Holmes Morton, Maple Syrup Urine Disease In GeneTests: Medical Genetics Information Resource (database online). Copyright, University of Washington, Seattle. 1993-2006 [http://www.genetests.org/query?dz=msud]
{{Portail médecine}}
[[Catégorie:Maladie génétique]]
[[Catégorie:Maladie génétique congénitale]]
[[Catégorie:Maladie génétique du métabolisme des acides aminés|Leucinose]]
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<!--Disease characteristics. The term "organic acidemia" or "organic aciduria" (OA) applies to a group of disorders characterized by the excretion of non-amino organic acids in urine. Most result from dysfunction, usually because of deficient enzyme activity, of a specific step in amino acid catabolism. The majority of the classic organic acid disorders result from abnormal amino acid catabolism of branched chain amino acids or lysine. They include maple syrup urine disease (MSUD), propionic acidemia, methylmalonic acidemia (MMA), isovaleric acidemia, biotin-unresponsive 3-methylcrotonyl-CoA carboxylase deficiency, 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) lyase deficiency, ketothiolase deficiency, and glutaric acidemia type I (GA I). A neonate affected with an OA is usually well at birth and for the first few days of life. The usual clinical presentation is that of a toxic encephalopathy and includes vomiting, poor feeding, neurologic symptoms such as seizures and abnormal tone, and lethargy progressing to coma. Outcome is enhanced by diagnosis in the first ten days of life. In the older child or adolescent, variant forms of the OAs can present as loss of intellectual function, ataxia or other focal neurologic signs, Reye syndrome, recurrent keto-acidosis, or psychiatric symptoms. A variety of MRI abnormalities have been described in the OAs, including distinctive basal ganglia lesions in GA I, white matter changes in MSUD, and abnormalities of the globus pallidus in methylmalonic acidemia.
Diagnosis/testing. Clinical laboratory findings that should suggest an organic acidemia include acidosis, ketosis, hyperammonemia, abnormal liver function tests, hypoglycemia, and neutropenia. Propionic acidemia may present with isolated hyperammonemia early in its course. First-line diagnosis in the organic acidemias is urine organic acid analysis using gas chromatography with mass spectrometry (GC/MS), utilizing a capillary column. The organic acids found in the urine provide a high degree of suspicion for the specific pathway involved. The urinary organic acid profile is nearly always abnormal in the face of acute illness with decompensation; however, in some disorders the diagnostic analytes may be present only in small or barely detectable amounts when the affected individual is not acutely ill. Depending on the specific disorder, plasma amino acid analysis can also be helpful. Plasma amino acid analysis requires a quantitative method such as column chromatography, high-performance liquid chromatography (HPLC), or GC/MS. Once the detection of specific analytes narrows the diagnostic possibilities, the activity of the deficient enzyme is measured in lymphocytes or cultured fibroblasts as a confirmatory test.
Genetic counseling. The organic acidemias considered -->
<!--Disease characteristics. Nephropathic cystinosis is characterized by poor growth, renal tubular Fanconi syndrome, renal glomerular failure, and involvement of other tissues and organ systems. In untreated individuals, failure to grow is generally noticed at six to nine months of age. With optimal symptomatic and cystine-depleting therapy, affected individuals grow at a normal rate but do not recover lost height unless growth hormone is administered. Signs of renal tubular Fanconi syndrome appear as early as six months of age and include polyuria, polydipsia, dehydration, and acidosis. Cystine-depleting therapy begun just after birth can attenuate the Fanconi syndrome; however, renal tubular damage present at the usual time of diagnosis (i.e., approximately one year of age) is irreversible. In untreated individuals, glomerular function gradually deteriorates, resulting in renal failure at approximately ten years of age. Early treatment with oral cysteamine slows or stops the progression of glomerular damage and can delay or prevent the need for renal transplantation. Intermediate cystinosis is characterized by all the typical early manifestations of nephropathic cystinosis, but at a later age. Renal glomerular failure occurs in all affected individuals, usually between 15 and 25 years of age. Non-nephropathic cystinosis is characterized by photophobia only.
Diagnosis/testing. The diagnosis of renal tubular Fanconi syndrome is established by documenting increased urinary losses of essential nutrients including electrolytes (sodium, potassium, bicarbonate), minerals (calcium, phosphate, magnesium), glucose, amino acids, carnitine, and water. These renal losses result in clinical symptoms such as hypophosphatemic rickets and growth retardation. A slit lamp examination of the cornea showing typical cystine crystals is diagnostic for cystinosis. Corneal crystals can be present before one year of age, and are always present after 16 months of age, at least in individuals with nephropathic cystinosis. All clinical diagnoses of cystinosis should be confirmed by measurement of leucocyte cystine, which is best performed using the cystine binding protein assay. Mutations in CTNS cause all three types of cystinosis. In the United States and northern European populations, approximately 40% of individuals with nephropathic cystinosis are homozygous for a 57-kb deletion. In individuals with intermediate and non-nephropathic cystinosis, the deletion can be present in the heterozygous state, along with a more "benign" mutation, but not in the homozygous state. PCR amplification across this deletion allows for molecular diagnosis of homozygotes as well as heterozygotes, and clinical molecular diagnosis is available. Clinical molecular diagnosis of other mutations in northern Europeans and other groups requires more laborious molecular diagnostic techniques and is available for specific population groups in a limited number of laborat-->
[[de:Ahornsirupkrankheit]]
[[en:Maple syrup urine disease]]
[[ja:メープルシロップ尿症]]
[[ms:Penyakit Kencing Sirap Maple]]
[[pl:Choroba syropu klonowego]]
[[pt:Doença da urina em xarope de ácer]]
[[ru:Лейциноз]]
[[simple:Maple syrup urine disease]]
[[sv:MSUD]]