Homocystinuria caused by cystathionine beta-synthase (CBS) deficiency is also called classical homocystinuria. CBS is an enzyme. Enzymes are proteins that regulate the body’s tissues and organs. Specifically, CBS helps convert an important amino acid—homocysteine—to another amino acid that the body needs.
When the body makes too little CBS enzyme or none at all, or it makes CBS enzyme that does not work properly, levels of homocysteine and methionine (also an important amino acid) in the blood increase. The high levels of homocysteine cause harmful symptoms to develop.
Classical homocystinuria can affect many parts of the body:
Learning problems and developmental delays, such as being slow to sit up, walk, or talk
Problems with the lenses in the eyes, such as lens dislocation; nearsightedness (often severe); quivering of the iris (the colored
part of the eye)
Tall, thin body with long arms, legs, fingers and toes; curved spine; osteoporosis (brittle or weak bones)
Development of blood clots
All states screen newborns for classical homocystinuria:
CYSTADANE (betaine anhydrous for oral solution) is indicated in children and adults for the treatment of homocystinuria to decrease high homocysteine blood levels. Homocystinuria is a rare genetic disorder in which there is an abnormal accumulation of the amino acid homocysteine in the blood and urine. The following are considered to be homocystinuria disorders: