Reader Question – Eduardo Apolinario Fumagalli,
Ronda Alta, RS
From the color of your eyes to the texture of your earwax, chromosomes are responsible for controlling every function in your body. They are formed by DNA, a chemical code composed of sequences of nitrogenous bases. It is these sequences, also known as genes, that contain specific instructions for how we function. Until 1990, little was known about this mechanism. This motivated scientists around the world to start a task force, the Genome Project, to locate the exact position of our 20,000 genes within the chromosomes. The project, which ended in 2003, mapped 70% of the human genetic code, enough to identify what each chromosome controls.
Each in its square
Discover the most interesting functions of genes
WHAT’S THERE, OLD MAN?
Have you ever thought about living only ten years? This can happen if a gene on chromosome 1 mutates and causes progeria, a rare premature aging disease. On the other hand, research centers are collecting genomes from healthy elderly people over 80 to discover how genetics contribute to a long life.
GOOD MUTANT
Mutations can be beneficial. Research has indicated that deformations in a gene on chromosome 3 can prevent the HIV virus from entering cells. Today, about 5% of the population is part of this group that, even infected by the AIDS virus, will never develop the disease
HORSEMEN OF THE APOCALYPSE
The chance of having cancer is influenced by genetic inheritance, but the location varies according to the affected chromosome. Genes 13 may increase breast cancer and 2 colon cancer. Diseases such as asthma (5) and Alzheimer’s (1, 14, 19, 21) are also associated with genetic mutations
ONE IS LITTLE, THREE IS TOO MUCH
An adult has 46 chromosomes in each cell divided into 23 pairs. The excess (or absence) of chromosomes can result in serious alterations in the body. The most common example is Down syndrome, whose carriers have an extra chromosome 21. In Turner syndrome, women are born with one less X chromosome. There are also Klinefelter, Patatau and Edwards syndromes.
THERE IS A SWAG
The type of earwax that comes out of your ear is also determined by genetic alterations, more precisely in the ABCC11 gene on chromosome 16. In Asians, for example, earwax is of the dry type, while in Europeans and Africans the most common is a wetter wax
CUTE ZES
Genes control all of our physical characteristics. Height, for example, is determined on chromosome 20. Eye color is the task of 15 (brown and blue eyes) or 19 (green). The chromosome responsible for skin color (16) is not the same one that determines albinism, which is the absence of pigmentation (11 and 15)
THE ECCENTRIC
Bipolar disorder is mostly determined by a genetic predisposition, as is schizophrenia. Both happen due to dysfunctions in chromosome 22 and research also indicates a relationship between the two diseases and autism. Children of schizophrenic or bipolar parents are up to three times more likely to be autistic
There are already devices capable of carrying out a genetic mapping of a person and identifying a predisposition to certain diseases. The gene test costs up to BRL 6 thousand
Men and mice have the same estimated number of genes. Therefore, some scientists suggest that human complexity is not in quantity, but in the way genes operate.
Gene therapy promises to replace a defective gene with a new normal gene, treating or even curing diseases.
READ MORE
– What is the difference between DNA, gene and chromosome?
– How is gene therapy performed?
CONSULTANCY Dr. Mayana Zatz, postdoctoral fellow in genetics and coordinator of the Center for Research on the Human Genome and Stem Cells at USP
SOURCES Guia Veja de Medicina e Saúde – Atlas do Corpo Humano, The Human Body: A Family Reference Guide, Portal Ponto Ciência, Report from the Center for Research on the Human Genome of USP, VEJA, National Institutes of Health, Medical News, iG and Portal Medical Genetics