You learn what letter your blood type is (A, B, AB, and O). You also learn what your Rhesus, or RH, factor is. Your blood is either RH+, meaning the blood has the RH factor, or RH-, meaning the RH factor is not in your blood.he c, e, and d genes are negative RH genes; meaning there is no RH factor in the blood. Research shows only the âDâ gene causes sensitivity issues, so itâs the D gene that is of concern during your pregnancy. Thatâs why some care providers call the RH factor RH (D) positive or RH (D) negative.
Definition of RETARDATION. 1. : an act or instance of retarding. 2. : the extent to which something is retarded. 3. : a musical suspension; specifically: one that resolves upward. 4. a: an abnormal slowness of thought or action; especially: mental retardation b: slowness in development or progress.
Definition of Rett syndrome. Rett syndrome: An X-linked dominant neurological disorder that affects girls only and is one of the most common causes of mental retardation in females.irls with the syndrome show normal development during the first 6-18 months of life followed first by a period of stagnation and then by rapid regression in motor and language skills. The hallmark of Rett syndrome is the loss of purposeful hand use and its replacement with stereotyped hand-wringing.