Cute features caused by gene mutations

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1 Cute features caused by gene mutations By ThoughtCo.com, adapted by Newsela staff on Word Count 727 Level 950L Dimples are most prominent when a person smiles. Photo by: Natashi Jay/Flickr. Our genes determine our physical features such as height, weight and skin color. These genes sometimes go through mutations that alter the physical traits we see in ourselves or others. DNA contains the instructions for how each part of the body works, and is passed on from parents to children. Genes are made up of tiny segments of DNA. Mutations are changes that occur in DNA. These changes can be inherited from our parents or acquired throughout our lifetime. While some mutations can lead to diseases or death, others may have no negative impact. They may even benefit someone. Still, other mutations can produce traits that are downright cute. Here are four cute features caused by gene mutations. This article is available at 5 reading levels at 1

2 Dimples Dimples are a genetic trait that causes the skin and muscles to form small divots in the cheeks. Dimples can occur in either one or both cheeks, and often show up when someone smiles. Dimples are typically passed down from parents to their children. These genes are found in the sex cells the sperm and the egg of the parents. When these sex cells come together, the genes are inherited by the children. If both parents have dimples, it is likely that their children will have them, too. If neither parent has dimples, then their children are not likely to have dimples. It is possible for parents with dimples to have children without dimples and parents without dimples to have children with dimples. Multicolored Eyes Some individuals have eyes with irises that are different colors. The iris is the colored part of the eye. This difference in colors between eyes is known as heterochromia and it can be complete, sectoral or central. In complete heterochromia, one eye is a different color than the other eye. In sectoral heterochromia, part of one iris is a different color than the rest of the iris. In central heterochromia, the iris contains an inner ring around the pupil that is a different color than the rest of the iris. Eye color is thought to be influenced by up to 16 different genes. It is determined by the amount of melanin, a brown coloring material, that a person has in the front part of the iris. Heterochromia is caused by a gene mutation that influences eye color and is inherited through sexual reproduction. Individuals that inherit this trait from birth typically have normal, healthy eyes. Heterochromia may also develop later in life. People can develop heterochromia as a result of disease or following eye surgery. This article is available at 5 reading levels at 2

3 Freckles Freckles are the result of a mutation in skin cells known as melanocytes. Melanocytes are located in the outer layer of the skin and produce melanin. Melanin gives the skin a brown hue. This helps to protect the skin from harmful ultraviolet rays (UV) that come from the sun. Too much sunlight can cause diseases such as skin cancer. A mutation in melanocytes can cause them to accumulate and produce an increased amount of melanin. This causes brown or reddish spots to form on the skin. In this case, the melanin has not been spread out evenly. Freckles develop as a result of two main factors: genetic inheritance and ultraviolet radiation exposure. Individuals with fair skin and blond or red hair tend to have freckles most commonly. Freckles tend to appear most often on the cheeks and nose, arms and shoulders. This article is available at 5 reading levels at 3

4 Cleft Chin This article is available at 5 reading levels at 4

5 A cleft chin, or dimple chin, is also caused by a gene mutation. When a baby is forming in the mother's womb, it starts out as a tiny embryo, which is the earliest stage of development. A dimple chin forms during the embryo stage. Bones or muscles in the lower jaw do not fuse together completely. This produces a small dimple, or indent, in the chin. Parents with cleft chins often pass this gene on to their children. However, just because a child has the gene doesn't mean they will get a cleft chin. Something could happen in the environment when the child is developing in the womb that makes them grow differently. Other genes known as modifier genes may also change how the chin develops. This article is available at 5 reading levels at 5