ABSTRACT
For more than a hundred years since the first experiments of Gregor Mendel, whose work is considered to be the foundation of modern genetics, very little changed. Then an exponential increase in knowledge occurred. In 1970, the first report of the linkage of a human disease to a chromosome was published (1). The discovery related to ophthalmology and described the linkage of congenital cataract to the Duffy blood group on chromosome 1. The location of the gene was later identified as position 22-23 on the long arm of chromosome 1 (1q22-1q23) (2,3). The gene was cloned in 1945 and in 1998 a mutation was identified on the gene for gap-junction protein alpha-8 (GJA8) (3). This gene encodes a connexin protein, which is about 50 kDa (kilodalton) in size, and primarily and abundantly expressed in the crystalline lens (3). The mutation identified was the substitution of serine for proline at codon 88 (Pro88Ser).
