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Ring Chromosomes

Table of Contents

Ring Chromosomes

Autosomal Ring Chromosomes in Human Genetic Disorders

Ring chromosomes usually occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure. The ring may or may not include the chromosome's constriction point (centromere). In many cases, genetic material near the ends of the chromosome is lost.

202206 Ring chromosome

Image by DataBase Center for Life Science (DBCLS)/Wikimedia

What Is a Chromosome?

Chromosomes illustration

Image by mcmurryjulie/Pixabay

Chromosomes illustration

Image by mcmurryjulie/Pixabay

What Is a Chromosome?

A chromosome is an organized package of DNA found in the nucleus of the cell. Different organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes--22 pairs of numbered chromosomes, called autosomes, and one pair of sex chromosomes, X and Y. Each parent contributes one chromosome to each pair so that offspring get half of their chromosomes from their mother and half from their father.

A chromosome is the structure housing DNA in a cell. Chromosomes are structurally quite sophisticated, containing elements necessary for processes such as replication and segregation. Each species has a characteristic set of chromosomes with respect to number and organization. For example, humans have 23 pairs of chromosomes--22 pairs of numbered chromosomes called autosomes, 1 through 22, and one pair of sex chromosomes, X and Y. Each parent contributes one chromosome of each pair to an offspring.

Eric D. Green, M.D., Ph.D.

Source: National Human Genome Research Institute (NHGRI)

Additional Materials (18)

Chromosome DNA and Gene Expression

Chromosome DNA

Image by TheVisualMD

Chromosome

A chromosome is an organized package of DNA found in the nucleus of the cell.

Image by National Human Genome Research Institute (NHGRI)

Chromosome

Image by National Human Genome Research Institute

Genetics Basics | Chromosomes, Genes, DNA | Don't Memorise

Video by Don't Memorise/YouTube

Human Chromosome 3-D

Video by National Human Genome Research Institute/YouTube

X chromosome

Medical visualization of a human X chromosome. The human X chromosome is one of the 2 chromosomes that determine a person's genetic sex. All human eggs contain a single X chromosome from the mother which will be passed on to her offspring. A sperm also contains a single chromosome from the father which will be passed on to his offspring, but it can be either and X or a Y chromosome. Therefore, it is the genetic contribution from the father that will determine whether the child is a boy (XY) or a girl (XX).

Image by TheVisualMD

Medical visualization of a human Y chromosome

The human Y chromosome is one of the 2 chromosomes that determine a person's genetic sex. All human eggs contain a single X chromosome from the mother which will be passed on to her offspring. A sperm also contains a single chromosome from the father which will be passed on to his offspring, but it can be either and X or a Y chromosome. Therefore, it is the genetic contribution from the father that will determine whether the child is a boy (XY) or a girl (XX).

Image by TheVisualMD

Chromosome

A schematic depiction of a coding region in a segment of eukaryotic DNA

Image by Thomas Splettstoesser (www.scistyle.com)

SMN1 and SMN2 Gene on Chromosome Rotation

Genetic biomarkers usually test for variation in specific genes. A test for SMN1 (the "survivor motor neuron" gene), however, detects the absence of a critical piece of that gene, usually located on chromosome number 5. Its absence means that there can be no SMN protein produced, which in turn means that motor neurons will die off and muscles that depend on those neurons will atrophy. What is unusual in the case of this genetic disorder is that we possess a similar, but less functional gene, called SMN2.

Image by TheVisualMD

Graphic decomposition of a chromosome (found in the cell nucleus), to the bases pair of the DNA

Graphic decomposition of a chromosome (found in the cell nucleus), to the bases pair of the DNA.

Image by File:Chromosome-es.svg: KES47 (talk)

Chromosomes and Karyotypes

Video by Amoeba Sisters/YouTube

What are Chromosomes?

Video by Bozeman Science/YouTube

Intro to Chromosomes & DNA

Video by GeneDx/YouTube

Chromosomes, Chromatids, Chromatin, etc.

Video by Khan Academy/YouTube

Human male karyotpe high resolution - Chromosome 17

The most common cause of CMT (70–80% of the cases) is the duplication of a large region on the short arm of chromosome 17 that includes the gene PMP22. Human male Karyotype after G-banding. Chromosome 17 highlighted

Image by National Human Genome Research Institute/Wikimedia

Medical visualization of a human X chromosome

The human X chromosome is one of the 2 chromosomes that determine a person's genetic sex. All human eggs contain a single X chromosome from the mother which will be passed on to her offspring. A sperm also contains a single chromosome from the father which will be passed on to his offspring, but it can be either and X or a Y chromosome. Therefore, it is the genetic contribution from the father that will determine whether the child is a boy (XY) or a girl (XX).

Image by TheVisualMD

FMR1 Gene test for Fragile X Syndrome

Fragile X syndrome is a genetic condition caused by a change in a gene called FMR1. A small part of the gene code is repeated on a fragile area of the X chromosome. The more repeats, the more likely there is to be a problem. In the accompanying image, the chromosome on the left is a healthy X chromosome, while the chromosome on the right is a fragile X chromosome. The "dangling" portions at the bottom of the chromosome on the right are characteristic of this condition.

Image by TheVisualMD

Chromosome with one end highlighting Telomeres

The image is a graphic representation of a chromosome with the end zones, called the telomeres, highlighted in white. The telomeres protect the genetic material within the chromosome. However, they shorten every time a cell divides. The image supports information about how stress interferes with the maintenance of the telomeres, and can contribute to shorter, unraveling telomeres. This eventually leads to cell death, a signal event of aging.

Image by TheVisualMD

Chromosome DNA and Gene Expression

TheVisualMD

Chromosome

National Human Genome Research Institute (NHGRI)

Chromosome

National Human Genome Research Institute

5:24

Genetics Basics | Chromosomes, Genes, DNA | Don't Memorise

Don't Memorise/YouTube

0:29

Human Chromosome 3-D

National Human Genome Research Institute/YouTube

X chromosome

TheVisualMD

Medical visualization of a human Y chromosome

TheVisualMD

Chromosome

Thomas Splettstoesser (www.scistyle.com)

SMN1 and SMN2 Gene on Chromosome Rotation

TheVisualMD

Graphic decomposition of a chromosome (found in the cell nucleus), to the bases pair of the DNA

File:Chromosome-es.svg: KES47 (talk)

7:33

Chromosomes and Karyotypes

Amoeba Sisters/YouTube

5:35

What are Chromosomes?

Bozeman Science/YouTube

2:11

Intro to Chromosomes & DNA

GeneDx/YouTube

18:23

Chromosomes, Chromatids, Chromatin, etc.

Khan Academy/YouTube

Human male karyotpe high resolution - Chromosome 17

National Human Genome Research Institute/Wikimedia

Medical visualization of a human X chromosome

TheVisualMD

FMR1 Gene test for Fragile X Syndrome

TheVisualMD

Chromosome with one end highlighting Telomeres

TheVisualMD

Ring 2

Human chromosome 02

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory

Human chromosome 02

Ideogram of human chromosome 2.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory

What Is Ring Chromosome 2?

Ring chromosome 2 is a very rare chromosome abnormality in which the ends of chromosome 2 join together to form a ring shape. The severity and symptoms associated with ring chromosome 2 vary from person to person. Slow growth, short stature and a small head size are common features, but people with ring chromosome 2 may otherwise be generally healthy with no major birth defects. Signs and symptoms present in some people may include failure to thrive, developmental delay, low muscle tone (hypotonia), distinctive facial features, skeletal abnormalities, and/or other birth defects involving the heart, genitals, or other parts of the body. Ring chromosome 2 typically is not inherited and occurs sporadically, during the formation of egg or sperm cells or shortly after the egg and sperm join together. Treatment for ring chromosome 2 depends on the signs and symptoms present in each person.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 9

Human chromosome 09 from Gene Gateway - no label

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

Human chromosome 09 from Gene Gateway - no label

Ideogram of human chromosome 9.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

What Is Ring Chromosome 9?

Ring chromosome 9 is a very rare chromosome abnormality in which the ends of chromosome 9 join together to form a ring shape. The resulting ring may be missing genes, or it may contain extra copies of genes. Therefore, the severity and symptoms associated with ring chromosome 9 vary from person to person. Signs and symptoms that may be present in a person with ring chromosome 9 include slow growth and short stature, learning disabilities, small head size, distinctive facial features, low muscle tone (hypotonia), skeletal abnormalities, and/or other birth defects involving various parts of the body. However, people with ring chromosome 9 can be generally healthy and have no major birth defects.

Ring chromosome 9 typically is not inherited and occurs sporadically, during the formation of egg or sperm cells or shortly after the egg and sperm join together. Occasionally, one of the parents has a chromosome abnormality involving chromosome 9. Chromosome testing of both parents can help determine whether the ring chromosome was inherited and whether future children have an increased chance to have a chromosome abnormality. Treatment for ring chromosome 9 depends on the signs and symptoms present in each person.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 13

Human chromosome 13 from Gene Gateway - no label

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

Human chromosome 13 from Gene Gateway - no label

Ideogram of human chromosome 13.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

What Is Ring Chromosome 13?

Ring chromosome 13 is a rare chromosome abnormality in which the ends of chromosome 13 join together to form a ring shape. When a ring forms, there may be missing genes where the chromosome's ends fuse together. Therefore, the severity and symptoms associated with ring chromosome 13 vary from person to person, depending on the number of genes, and specific genes, involved. Most people with ring chromosome 13 also have cells with 46 normal chromosomes (this is called mosaicism), which can lessen the effect of the ring chromosome on growth and development.

Signs and symptoms that may be present in a person with ring chromosome 13 include developmental delay, slow growth and short stature, feeding difficulties, learning difficulties, a small head size, abnormal formation or positioning of the feet and/or toes, and/or abnormalities of the palate (roof off the mouth). Depending on how many genes are lost and how many normal cells a person has, additional features or birth defects may also be present.

Ring chromosome 13 typically is not inherited, occurring sporadically during the formation of egg or sperm cells or shortly after the egg and sperm join together. In some cases, ring chromosome 13 is inherited from a parent. Chromosome testing of parents can help determine whether the ring chromosome was inherited and whether future children have an increased chance to have a chromosome abnormality. Treatment for ring chromosome 13 depends on the signs and symptoms present in each person.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 14

Human chromosome 14 from Gene Gateway - no label

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

Human chromosome 14 from Gene Gateway - no label

Ideogram of human chromosome 14.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

What Is Ring Chromosome 14?

Ring chromosome 14 is a rare chromosome abnormality that causes ring chromosome 14 syndrome (written as r(14) syndrome), which affects many parts of the body. Signs and symptoms of r(14) syndrome vary from person to person but often include distinctive facial features, developmental delay and intellectual disability, autism spectrum disorder, intractable (hard to control) epilepsy, and occasional eye and vision abnormalities. Intellectual disability ranges from moderate to severe, likely depending on the severity of seizures and age they begin (earlier onset is associated with more severe disability). Severity and frequency of seizures may improve over time. Other signs and symptoms may include a small head size (microcephaly), low muscle tone (hypotonia), scoliosis, and increased susceptibility to infections.

Ring chromosomes almost always occur sporadically (by chance), occurring for the first time in people with no family history of chromosome disorders. In these cases, it occurs as a random event when egg or sperm cells are formed, or very soon after the egg and sperm join together. Researchers believe that several important genes near the end of the long arm of chromosome 14 are lost (deleted) when the ring forms, likely leading to some of the features of r(14) syndrome.

Management depends on the symptoms in each person and often requires a team of specialists to address each medical issue. Because symptoms and severity can vary, the long-term outlook (prognosis) is difficult to predict and depends mainly on the health issues present and complications that may arise.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 15

What Is Ring Chromosome 15?

Ring chromosome 15 is a chromosome abnormality that affects growth, learning, and speech. People with ring chromosome 15 often have growth delays before and after birth, resulting in short stature; varying degrees of intellectual disability; low muscle tone (hypotonia); craniofacial malformations; and limb abnormalities. Other symptoms might include congenital heart defects, kidney problems, congenital dislocation of the hips, and cafe-au-lait spots. Ring chromosome 15 is caused by an abnormal chromosome known as a ring chromosome 15 or r(15). A ring chromosome is a circular structure that occurs when a chromosome breaks in two places and the broken ends fuse together. The features of ring chromosome 15 appear to result from the loss (deletion) of genetic material from the long (q) arm of chromosome 15. Ring chromosome 15 is usually caused by spontaneous (de novo) errors very early in embryonic development. In rare cases, it is passed through families, either from a parent who also has a ring chromosome 15, or from a parent who has a balanced translocation. Treatment for ring chromosome 15 is focused on addressing the symptoms present in each individual and may require a team of medical specialists.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 16

Ideogram of human chromosome 16

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science

Ideogram of human chromosome 16

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science

What Is Ring Chromosome 16?

Ring chromosome 16 is characterized by postnatal growth deficiency, intellectual disability, microcephaly, broad flat nasal bridge, down-turned mouth, low-set and dysmorphic (abnormally-shaped) ears and speech delay. To date, less than 10 cases have been reported in the medical literature.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 18

Human chromosome 18 from Gene Gateway - no label

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

Human chromosome 18 from Gene Gateway - no label

Ideogram of human chromosome 18.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

What Is Ring Chromosome 18?

Ring chromosome 18 is a rare chromosome abnormality in which the ends (arms) of chromosome 18 join together to form a ring shape. When a ring chromosome forms, genetic material can be lost from either arm or both arms, causing various signs and symptoms. While most people with ring chromosome 18 have the ring chromosome in all of their body cells, some people also have some body cells with normal chromosomes (this is called mosaicism). People with ring chromosome 18 mosaicism may have milder symptoms.

Depending on the amount of genetic material lost and which genes are involved, signs and symptoms that may be present in a person with ring chromosome 18 include ear and hearing abnormalities, abnormally-developed feet or hands, genital abnormalities in males, an increased risk to develop juvenile rheumatoid arthritis, holoprosencephaly, developmental delays, learning difficulties, short stature, and/or various birth defects.

Ring chromosome 18 usually occurs sporadically (by chance) during the formation of egg or sperm cells or shortly after the egg and sperm join together. Occasionally, it is inherited from a parent (typically the mother). A chromosome test of the parents can help determine whether it was inherited and whether future children have an increased chance to have a chromosome abnormality. Treatment for ring chromosome 18 depends on the signs and symptoms present in each person.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 20

Human chromosome 20 from Gene Gateway - no label

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

Human chromosome 20 from Gene Gateway - no label

Ideogram of human chromosome 20.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

What Is Ring Chromosome 20?

Ring chromosome 20 is a chromosome abnormality that affects the development and function of the brain. People with ring chromosome 20 often have recurrent seizures or epilepsy. Other symptoms might include intellectual disability, behavioral difficulties, growth delay, short stature, a small head (microcephaly), and characteristic facial features. Ring chromosome 20 is caused by an abnormal chromosome known as a ring chromosome 20 or r(20). A ring chromosome is a circular structure that occurs when a chromosome breaks in two places and its broken ends fuse together. Ring chromosome 20 is usually not inherited. It almost always occurs by chance during the formation of reproductive cells (eggs or sperm) or in early embryonic development. Treatment for ring chromosome 20 is focused on management of seizures and accommodations for learning.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 21

Human chromosome 21 from Gene Gateway - no label

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

Human chromosome 21 from Gene Gateway - no label

Ideogram of human chromosome 21.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

What Is Ring Chromosome 21?

Ring chromosome 21 is a rare chromosome abnormality in which the ends of chromosome 21 join together to form a ring shape. Many people with ring chromosome 21 have normal development and are healthy, having been diagnosed after having chromosome testing due to infertility, multiple miscarriages, or a child with a chromosome abnormality. However, others with ring chromosome 21 have developmental and/or medical problems which can range from mild to severe. This is due to having extra or missing genetic material on the ring chromosome, which can happen when the ring chromosome forms. Signs and symptoms of ring chromosome 21 that may be present can include short stature, delayed puberty in males, small head size, seizures, learning disabilities, underdeveloped sex organs, susceptibility to infections, and/or a variety of birth defects. Some people have signs and symptoms similar to those that occur in people with Down syndrome.

Ring chromosome 21 may be inherited from a parent (typically the mother), or it may occur sporadically (by chance) during the formation of egg or sperm cells or shortly after the egg and sperm join together. A chromosome test of the parents can help determine whether it was inherited and whether future children have an increased chance to have a chromosome abnormality. Treatment for ring chromosome 21 depends on the signs and symptoms present in each person.

Source: Genetic and Rare Diseases (GARD) Information Center

Ring 22

Human chromosome 22

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

Human chromosome 22

Ideogram of human chromosome 22.

Image by Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science, the Biological and Environmental Research Information System, Oak Ridge National Laboratory./Wikimedia

What Is Ring Chromosome 22?

Ring chromosome 22 is a rare condition caused by having an abnormal chromosome 22 that forms a ring. In this chromosome abnormality, a segment on the short (p) arm and a segment on the long (q) arm of 22 are missing. The amount of material lost varies from person to person. The remaining ends of chromosome 22 have joined together to make a ring shape. Chromosome 22 is an acrocentric chromosome, meaning that the centromere is near one end, creating a very small short (p) arm that does not contain genes that are relevant to development. Thus, only the lost genes on the long (q) arm matter. Knowing the breakpoint in the long arm is likely more helpful. Most cases are sporadic (happen by chance) and occur in people with no history of the condition in their family.

Source: Genetic and Rare Diseases (GARD) Information Center

Related HealthJournals

Ring Chromosome 14 Syndrome

Ring chromosome 14 syndrome is a condition characterized by seizures and intellectual disability. Recurrent seizures (epilepsy) develop in infancy or early childhood. Explore symptoms, inheritance, genetics of this condition.

Ring Chromosome 20 Syndrome

Ring chromosome 20 syndrome is a condition that affects the normal development and function of the brain. The most common feature of this condition is recurrent seizures (epilepsy) in childhood. Explore symptoms, inheritance, genetics of this condition.

Chromosome Disorders

Chromosome disorders can be classified into two main types; numerical and structural. Numerical disorders occur when there is a change in the number of chromosomes (more or fewer than 46). Structural chromosome disorders result from breakages within a chromosome. Learn more about chromosome disorders.

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Ring Chromosomes

Ring chromosomes usually occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure. The ring may or may not include the chromosome's constriction point (centromere). In many cases, genetic material near the ends of the chromosome is lost.

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