Tetrasomy 12p

Tetrasomy 12p is a multi-system disorder that is characterized by extremely weak muscle tone (hypotonia) in infancy and early childhood, intellectual disability, distinctive facial features, sparse hair, areas of unusual skin coloring (pigmentation), and other birth defects. The signs and symptoms of Tetrasomy 12p vary in severity. Tetrasomy 12p is usually caused by the presence of an abnormal extra chromosome 12 called isochromosome 12p. Other, more complex chromosomal changes involving chromosome 12 may cause the syndrome in rare cases.

Genetic Mutations: Tetrasomy 12p is caused by genetic mutations, also known as pathogenic variants. Genetic mutations can be hereditary, when parents pass them down to their children, or they may occur randomly when cells are dividing. Genetic mutations may also result from contracted viruses, environmental factors, such as UV radiation from sunlight exposure, or a combination of any of these.

If you suspect you may have this disease, you may want to start collecting your family health history. Information such as other family members who have had similar symptoms, when their/your symptoms first appeared, or exposures to any potential disease-causing environmental factors should be discussed with your medical team.

Chromosomal Changes: Tetrasomy 12p is caused by a change in the number of chromosomes a person has, or a change in their structure. Chromosomes are structures within cells that hold all our genes. People usually have 46 chromosomes, 23 come from the biological mother and 23 come from the biological father. Most of the time, chromosomal changes occur randomly in the sperm or egg, but some changes are known to be passed on from parent to child.

Given the known chromosomal changes for this disease, you may want to ask your health care team if chromosome testing is right for you. Results from chromosome testing can confirm or rule out a suspected chromosomal disease or help determine a person’s chance of passing on a disease.