Pathological alterations typical of human Tay-Sachs disease, in the retinaof a deep-sea fish

Micrographs of retinas from the deep-sea fish Cataetyx laticeps revealed vi sual cells containing membranous whorls in the ellipsoids of the inner segm ents resulting from stretching and modifications of the mitochondria membra nes and their cristae. These pathological structures seem to be homologous to the whorls observed in retinas of human carriers of Tay-Sachs disease. T his disease, a genetic disorder, is found in humans and some mammals. Our f indings in fish suggest that the gene responsible can be found throughout t he vertebrate evolutionary tree, possibly dormant in most taxa.