Newborn screening for homocystinuria

Homocystinuria is a rare condition caused by mistakes in a gene that is responsible for making an enzyme called cystathionine beta synthase (CBS). People with homocystinuria have a deficiency of this enzyme and as a result have high levels of a substance called homocysteine in their bodies. Although such individuals appear normal at birth, over a period of months and years, they develop serious problems that effect eyesight, lead to delayed mental development, cause unhealthy bones, and have a high risk of having blood clots. Treatment with a special diet and medicines can prevent the development of these complications, but must be started very early in life to be truly effective. In some parts of the world homocystinuria has been tested for in newborn babies. The aim of this review was to identify and assess the results of any controlled clinical trials where homocystinuria was tested for in newborn infants, that would allow us to draw conclusions based on the highest level of evidence. No such trials were found. We know of some uncontrolled studies which suggest that newborn screening for homocystinuria and its early treatment are effective. Future long-term research is needed to provide strong evidence for or against screening. This research may also show whether screening is cost effective.