Glossary of genetic disorders. A physician specializing in diagnostic techniques for viewing internal organs and tissues without surgery. Radioulnar Relating to both the radius and ulna, the two bones in the lower arm between the elbow and wrist. Rami Dividing of a nevus or blood vessel.
Rarefaction Become lighter or less dense.
Recessive A gene that is phenotypically manifest in the homozygous state but is masked in the presence of a dominant allele. Autosomal recessive disorders develop in persons who receive two copies of the mutant gene, one from each parent who is a carrier. Recombination Crossing over. When the effect of a mutated gene for a dominant disease is somehow modified or reduced and does not always cause disease when present. Redundant Repeated or duplicated unnecessarily.