الفهرس 
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Abstract
Major advances have been made in elucidation of the molecular pathologies
of many genetic diseases. These advances enable geneticists to deal with
genetic diseases on basis of adequate knowledge. This knowledge provides essential background to build up an effective way of diagnosis, screening, prevention and treatment.
Genetic basis of genetic disorders
All living organisms use the same genetic code and this facilitate genetic studies when done on experimental animal which can give us an idea about •
what could occur in human which contain genetic defect.
The types of inheritance of genetic diseases are either Mendelian, mitochondrial or multifactorial. Types of mutation include deletion, insertion, duplication, and dynamic mutation.
Genetic polymorphism is very important and sites of polymorphism on .the chromosome can be used as genetic marker for other unknown gene loci using linkage studies. Linkage studies have important applications and it can be used for carrier detection, prenatal diagnosis gene mapping and presymptomatic diagnosis. Forward genetics can be use when abnormal gene product is known while reverse genetics can be used.when•knowledge of the defective gene product is not available.
The aim of the reverse genetics is to localize the disease gene locus to a chromosomal region •in order to identifY the defective gene product. It is useful in neurological disorders particularly autosomal dominant disorders.
Neurological diseases with genetic basis
The clue or successful treatment is the complete understanding of the
molecular biology an its rule in the pathogenesis of any neurological disorders. Recent advances in the field of genetic researches allow the identification of specific gene loci for most of the neurological disonlers. This is the first step to understand the mechanism by which a genetic mutation can result in certain phenotype and leading to the disability cause by this specific disorder. Neurological disorders was classified according to site of pathology into disorders that involve the brain, spinal cord, anterior hom cells, peripheral nerves, neuromuscular junction muscular disorders. In each neurological disorder the most recent gene locus identified was mentioned together with mentioning new classifications that was settled after the appearance of new gene loci for certain neurological disorders. New classifications and categorization systems are another important step in way to successful treatment. New treatment strategies will aim to tailor specific treatment for each gene type and not merely symptomatic treatment.