Canavan disease: Year of the Zebra

DUPLICATE

From cars to airplanes, machinery must be built and maintained with specialized tools to function properly. Any anticipated expansions would be a much bigger endeavor. Although incomparable to inanimate objects, the human brain also needs a whole host of processes to maintain it. To go even further, the intense periods of brain growth in children add a whole level of complexity to the equation. Canavan disease is a rare genetic neurological disorder characterized by the spongy degeneration of the white matter in the brain. It belongs to a group of disorders known as the leukodystrophies. Each type of leukodystrophy is caused by an abnormality of a specific gene that results in the abnormal development of one of at least 10 different chemicals that make up the white matter of the brain. In Canavan disease, the ASPA gene which metabolizes a substance called N-acetylaspartic acid (NAA) is affected, leading to the accumulation of the latter and all the ensuing effects. The disorder usually becomes apparent between 3 and 6 months of age and the initial symptoms usually include extremely poor head control, an abnormally large head, and severely diminished muscle tone (hypotonia) resulting in 'floppiness.' Affected infants may be generally unresponsive, lethargic, or irritable. Some infants may experience difficulty swallowing (dysphagia), which contributes to feeding difficulties. It affects all ethnic groups but occurs with greater frequency in individuals of Ashkenazi Jewish descent. The overall incidence of Canavan disease in the general population is unknown. To learn more about the diagnosis and treatment of Canavan disease, watch the dedicated Osmosis video on YouTube and Osmosis.org.