How to Diagnose Canavan Disease

With a life expectancy ranging only into the teens, Canavan disease is a particularly serious genetic disorder that causes the brain to slowly degenerate into a porous, spongy tissue. Infants aged three to five months will begin to show signs of the disorder, with developmental difficulties, an enlarged head and poor control of the head being the most common symptoms. Read on to learn how to diagnose Canavan disease.

Instructions

Difficulty: Moderately Challenging

1. Understand the primary symptoms. The so-called "triad of Canavan disease" includes the presence of poor muscle tone, macrocephaly (disproportionately large head) and an inability to control the head. The presence of this set of symptoms should immediately raise suspicion of Canavan disease. Your doctor will then proceed to try and diagnose the disorder using one of a variety of screening techniques.
2. Know that a doctor can diagnose Canavan disease pre-natally by sampling amniotic fluid (fluid found in the womb surrounding the fetus). A chromosome analysis of the amniotic fluid will reveal any chromosomal or genetic disorders afflicting the fetus. These are typically performed beginning sometime after the eleventh week of pregnancy.
3. Have a doctor perform a blood test to diagnose Canavan disease. The presence of large quantities of N-acetylaspartic acid (NAA) in the blood (or fluid taken from the spine) indicates the probable presence of Canavan disease.
4. Prepare for a urine test to be performed. This test will analyze a urine sample for a high NAA count to confirm the findings of a blood test or vice-versa. Even Canavan disease sufferers with relatively low NAA output have levels between five and ten times higher what is found in the unaffected population.
5. Keep in mind that skin, white blood cells and enzymes can also be tested for signs of the disease. However, a karyotyping test that analyzes a patient's chromosomes is the most reliable means of detecting Canavan disease. A karyotyping test will generally be ordered by your physician or pediatrician as soon as the disorder is suspected.
6. Learn more and link to support resources at the Canavan disease pages on the National Institute of Neurological Disorders and Stroke (NIDS) website. See the Resources section below for a link.

Tips & Warnings

• Canavan disease is an "autosomal recessive" disorder. That means the chances of siblings of an affected child being affected themselves breaks down thus: there is a 25 percent chance that siblings will also have Canavan disease, a 25 percent chance they will not and a 50 percent chance they carry the disorder in a recessive gene.