Defective genes - everybody has some
In 2003, the human genome project, which required 13 years to complete, yielded a complete blueprint Homo sapiens. The genetic information is stored on 23 chromosomal pairs in the nucleus of human cells. One complete set, known as a haploid contains about 23,000 protein-coding genes. According to a new study published on February 17 in the journal Science, the average individual goes through life with 20 nonfunctioning genes; these genes represent about 0.1% of one’s total genetic makeup.
Lead author Daniel G. MacArthur of the Wellcome Trust Sanger Institute in England was assisted in the research by 49 other scientists located around the globe. Dr. MacArthur noted that the study suggests that human tolerance have a greater tolerance for mutated genes than previously thought. The defective genes vary between individuals; according to the researchers, at least 250—and probably many more—are not essential for normal function. Undoubtedly, some conceptions result in a greater number of defective genes; it is reasonable to assume that these pregnancies do not advance and result in a miscarriage, sometimes before a woman becomes aware that she is pregnant.
Obviously, nonfunctioning genes that do not impact one’s daily routines are ones that do not regulate essential functions. Their loss might manifest as a decreased sense of smell or reduced muscle power. When individuals are compared, genetic endowments vary. For example, some have greater intelligence while others are better at sports. Lance Armstrong, for example, who won the grueling Tour de France cycling event a record seven times, was endowed with an especially efficient heart.
The new study represents the latest attempt to understand the human genome. Despite the new information, the normal function of nonessential genes is unknown—it is merely known that they are broken. DNA coding is comprised of a sequence of nucleotide bases: adenine, guanine, cytosine, and thymine. Any alteration in the sequence disrupts is normal function; however, by determining which genes defective genes do not impact normal function, as well as pinpointing what the molecular damage consists of is an ongoing project for the researchers. They are developing a reference manual that should be useful to geneticists. It will be of particular value for aiding in the determination of whether newly discovered mutations are likely to cause disease.
As geneticists gain additional knowledge regarding how genes interact with each other in complex networks, they might be able to determine what determines an individual’s uniqueness in regard to which traits and individual has as well as what she or she lacks.
Adding to the complexity of understanding the human genome is the fact that only about 1.5% of human genetic material contains protein-coding genes, the rests consists of material, which has been termed “junk DNA.”