Rare genetic diseases can arise from unsuspecting carriers
When two people with a rare form of deafness mate, the genetic combination can yield an unusual syndrome in which the child has fragile bones, deafness, blindness and albinism.
The disorder is an example of a rare disease passed on by parents who do not exhibit the condition. It occurs through genetic combination and mathematical permutation (as autosomal recessive inheritance). Two children were identified with the COMMAD syndrome, and each has two different recessive mutations of the gene that codes for microphthalmia-associated transcription factor (MITF).