In autosomal recessive inheritance, a child must inherit two copies of the gene for RP — one from each parent — to develop the condition. This form of RP tends to cause symptoms early in life.

In this trait, the allele doing the overpowering, which is called the dominant allele, codes for brown eyes. The recessive allele, which is the one that stays hidden, codes for blue eyes.

F or years, it’s been commonly believed that mutts are healthier than purebred dogs. After all, the thinking goes, purebreds come from a smaller gene pool, making them more prone to health issues. But ...

Recessive dystrophic epidermolysis bullosa is characterized by extensive blistering and severe skin wounds caused by a mutation in the COL7A1 gene.