molecular genetic diagnosis of canavan disease in iran

canavan disease is a rare, autosomal recessive inherited, neurological disorder, classified as a leukodystrophy. the symptoms of canavan disease appear in early infancy and progress rapidly. most infants with canavan disease appear normal early in life. by three to five months of age, macrocephaly, lack of head control, and developmental delays become apparent. developmental delay becomes more obvious with increasing age. children with canavan disease are especially delayed in their motor skills. they are sometimes irritable and are not able to sit, stand, walk, or talk. as children with canavan disease get older, the hypotonia gives way to spasticity.although optic atrophy is present, the children are not blind and are often able to visually track objects. hearing is usually not impaired. as they get older, children may experience sleep disturbance, seizures, and feeding difficulties. the life expectancy is variable some children die in the first few years of life, while others survive into their teens or beyond. diagnosis of canavan disease in symptomatic individuals relies upon demonstration of very high concentration of n-acetyl aspartic acid (naa) in the urine. aspa, the gene encoding the enzyme aspartoacylase, is the only gene known to be associated with canavan disease. the aspa gene is located on the short (p) arm of chromosome 17 between the end (terminus) of the arm and position 13.three common mutations (--693c-->a, 854a-->c, and 914c-->a-- )account for about 99% of the disease-causing alleles in ashkenaza jewish persons and approximately 50-55% of disease-causing alleles in non-jewish persons. sequence analysis of the aspa coding region accounts for 87% of the patients and the rest of the affecteds have large genomic deletion /duplication comprising one or more exons. fourtunately recently molecular genetic diagnosis of canavan disease and measurement of the concentration of naa in the urine are available in iran. during the last 8 months 3 patints presumed to have canavan disease were referred to our lab and molecular diagnosis for canavan disease was performed and all the three were normal.