Heredity in Deafness Rachel Malinowski Christine Keogh Jon Bordogna Melissa Snyder

Facts n 1 in 2,000 children are born deaf n Deafness can occur by itself or as part of a syndrome n Over 28 million Americans are deaf n Deafness is caused by over 100 genetic disorders n Recessive inheritance is most common form of genetic deafness, accounting for approx. 80% of inherited deafness

Causes n Multi-gene trait--no obvious difference between deafness caused by different genes, so finding the genes involved is very difficult. Some Examples Are….

–chromosome 5q31 n single nucleotide substitution leading to a four- base pair insertion in messenger RNA and a frameshift. –Mutation: 1555(12s rRNA)7445(tRNA serine) n Mitochondrial DNA, only inherited from mother. n Changes in Mitochondrial DNA deafness explains 1% of genetic deafness. –Gene KCNQ1 and KCNQ4 n prevents secretion of potassium into the fluid that surrounds sensory cells of the ear. –Dominant Autosomal Deafness (DFNA) n Appears late in life, develops slowly

Autosomal Dominant - 5q I II III