The new medicine, eteplirsen, is targeted at the 13% of those boys whose muscular dystrophy is caused by a certain type of mutation.

FORBES: In A First, An Experimental Drug May Help Boys With Muscular Dystrophy

One big question: would the limited data Sarepta has so far collected from a very small clinical trial of its drug eteplirsen, a treatment for Duchenne muscular dystrophy that is caused by a very specific type of mutation, be enough to warrant filing with the Food and Drug Administration and perhaps even gain approval?

FORBES: A Key Exchange On Sarepta Therapeutics' Promising Muscular Dystrophy Drug

Oculocutaneous albinism type 4, caused by a gene mutation on chromosome 5, is an uncommon form of the disorder generally presenting signs and symptoms similar to those of type 2.

CNN: Albinism

Oculocutaneous albinism type 1 is caused by a mutation in a gene on chromosome 11.

CNN: Albinism

Oculocutaneous albinism type 2 is caused by a mutation in a gene on chromosome 15.

CNN: Albinism

The rarer oculocutaneous albinism type 3 is caused by a gene mutation on chromosome 9 and has been primarily identified in black South Africans.

CNN: Albinism

With the help of Chiara Cirelli, who also works at the University of Wisconsin, Dr Tononi has created a mutant fruit fly that sleeps only two or three hours a night. (A normal fly sleeps between eight and 14 hours.) The mutation itself is in a gene for a nerve-cell protein of a type known as an ion channel.

ECONOMIST: Memory formation