There may more often be detectable abnormalities at the cellular or biochemical levels when a woman is heterozygous for an X-linked recessive mutation than when she is heterozygous for an autosomal recessive mutation. Even though methylated cytosine is not copied as such during DNA replication, patterns of cytosine-methylation are reproduced from one generation of cells to the next during embryogenesis. Research on cystic fibrosis has been aided by genetically engineering mice to have defects in their CFTR genes. The Human Genome Project was begun in 1989 and essentially completed in June, 2000. In the finding and cloning of the defective gene that causes cystic fibrosis .
Cystic fibrosis is inherited as .
The finding of a gene by reverse genetics is equivalent to finding the gene by positional cloning. Mutations in genes for structural proteins often result in genetic diseases with a dominant mode of inheritance. Hearing loss is a common symptom in osteogenesis imperfecta. The collagen molecule consists of a helical arrangement of four polypeptide chains. Premature termination of the translation of a protein is the usual result of . . .