Abnormal: Differing from normal.
Accumulation: The process of acquiring more or the build-up of a substance.
Ammonia: A product of protein digestion.
Amino Acids: Amino acids combine to form proteins and when proteins are digested amino acids remain – amino acids are either essential (obtained through the diet) or non-essential (made by the body from the essential amino acids).
Amniocytes: Cells in the amniotic fluid surrounding the fetus before birth.
Amniotic Fluid: The fluid surrounding the fetus inside the uterus.
Analysis: Examination to discover characteristics or meanings.
Anorexia: Loss of appetite.
Arginine: Non-essential Amino Acid (made only by the urea cycle).
Argininosuccinate or Argininosuccinic Acid: A molecule made by the urea cycle.
Aspartate: Non-essential Amino Acid (made only by the urea cycle).
Assay: Assessment of characteristics (as weight, measure, or quality).
Athetosis: Repeated slow movements especially of the arms and legs due to brain dysfunction.
Autosomal Recessive Inherited Disorder: Two copies of an abnormal gene inherited from both parents that is capable of producing disease, specifically on one of 22 pairs of autosomes (non-sex linked).
Autosomes: Any of the non-sex determining chromosomes.