Paracentric chromosome inversion
A basic type of chromosome rearrangement. A segment that does not include the centromere (and so is paracentric) has been snipped out of a chromosome, turned through 180 degrees (inverted), and inserted right back into its original location in chromosome. The feature that makes it paracentric is that both breaks are on the same side of the centromere so that the centromere (the point at which the chromosome attaches to the spindle) is not affected.
Any chromosome inversion can be inherited and have come from one of the parents to a child. Or the inversion can appear for the first time in a child.
An inversion can be “balanced,” meaning that it has all the genes present in the normal uninverted chromosome. Or an inversion can be “unbalanced,” meaning that genes been have deleted (lost) or duplicated.
A balanced inversion in a child causes no problems. An unbalanced inversion is abnormal and is often associated with problems such as development delay (and later, mental retardation) and multiple congenital anomalies (birth defects).
Inversions can also be acquired in a body cell (a somatic cell) and in the process, disrupt a gene. This can be a step involving that cell in a precancerous and cancerous process.
Read Also:
- Paradoxical embolism
Passage of a clot (thrombus) from a vein to an artery. When clots in veins break off (embolize) , they travel first to the right side of the heart and, normally, then to the lungs where they lodge. The lungs act as a filter to prevent the clots from entering the arterial circulation. However, when […]
- Paragonimiasis
Infection with the trematode (parasitic worm) Paragonimus. More than 10 species of trematodes (flukes) of the genus Paragonimus infect humans, the most common being Paragonimus westermani, the oriental lung fluke. While P. westermani occurs in the Far East, other species of Paragonimus are encountered in Asia, the Americas, and Africa. Human infection with P. westermani […]
- Parainfectious
Occurring at the time of and in association with an acute infection or an episode of infection. For example, transverse myelitis (a disorder of the spinal cord) can occur parainfectiously in association with a number of viral and bacterial illnesses.
- Parainfluenza
A disease due to an acute respiratory infection caused by a parainfluenza virus. Parainfluenza usually occurs in children. The clinical picture can range from a relatively mild influenza-like illness to bronchitis, croup, and pneumonia.
- Paralysis
Loss of voluntary movement (motor function). Paralysis that affects only one muscle or limb is partial paralysis, also known as palsy; paralysis of all muscles is total paralysis, as may occur in cases of botulism.