Pallister-Killian Mosaic Syndrome ... (Pallister-Killian Mosaic Syndrome) - chromosome 12
Mosaic Pallister-Killian syndrome is a developmental disorder that affects many parts of the body and is characterized by hypotonia, mental retardation, distinctive facial features, sparse hair, skin areas with unusual pigmentation and other birth defects.
Most newborns with mosaic Pallister-Killian syndrome are born with significant hypotonia which can cause respiratory distress, feeding problems and problems in developing motor skills. About 30% of affected individuals get ultimately be able to walk unassisted. The developmental delays also result from intellectual disability, often severe to profound. Often speech is limited or absent in people with this condition.
The facial appearance of individuals with mosaic Pallister-Killian syndrome includes a high and rounded forehead, a broad nasal bridge, a short nose, very spaced eyes, low - set ears, round cheeks and a wide mouth with a thin upper lip and a large tongue. In addition, some affected children are born with cleft palate or arched palate. Most children with mosaic Pallister-Killian syndrome have little hair on the head and skin areas that are darker or lighter than the surrounding skin. These skin changes can occur anywhere on the body, and may be evident at birth or appear later in life.
Additional features mosaic Pallister-Killian syndrome may include hearing loss, vision problems, seizures, extra nipples, genital abnormalities and heart defects. Affected individuals may also have skeletal abnormalities such as extra digits on the hands or feet, toes, big feet, and unusually short arms and legs. About 40% of affected children are born with a diaphragmatic hernia, which can cause the stomach and intestines move into the chest, which can move the development of the heart and lungs.
Signs and symptoms of mosaic Pallister-Killian syndrome can vary, although most of those affected manifest severe to profound mental retardation and other serious health problems. The most severe cases involve birth defects that endanger life in early childhood. However, several people affected have expressed milder features, including mild intellectual disability and less noticeable physical abnormalities.
This process is usually due to the presence of an extra chromosome known as abnormal isochromosome 12p a i (12p). A isochromosome is a chromosome with two identical arms. Normal chromosomes have a long arm and a short one, but long arms isochromosomes have two or two short arms. Isochromosome 12p is a version of chromosome 12 in which there are two short arms. Cells normally have two copies of each chromosome, one inherited from each parent. In people with Pallister-Killian Mosaic Syndrome, cells have the usual two copies of chromosome 12, but some cells also have the isochromosome 12p. These cells have a total of four copies of all genes on the short arm of chromosome 12. The additional genetic material isochromosome interrupts the normal course of development, resulting in the characteristic features of this syndrome. Although the mosaic Pallister-Killian syndrome is usually due to the presence of isochromosome 12p, in rare cases some more complex chromosomal rearrangements involving chromosome 12 and are responsible for the disease.
Mosaic Pallister-Killian syndrome is not inherited. Chromosomal responsible change usually occurs as a random event during the formation of reproductive cells in one of the parents of the affected person, usually the mother, so that those affected have no history of the disease in their families. An error in cell division called nondisjunction probably results in a reproductive cell containing a 12p isochromosome. If this atypical reproductive cells contributes to the genetic makeup of a child, the child will have two normal copies of chromosome 12, along with a 12p isochromosome. As cells divide in early development, some cells lose isochromosome 12p, while other cells retain the abnormal chromosome, a condition known as mosaicism. Almost all cases of mosaic Pallister-Killian syndrome are due to mosaicism for 12p isochromosome. If all the body 's cells had the isochromosome, the resulting syndrome probably would not be compatible with life.
Tests in IVAMI: IVAMI perform observation in karyotype.
Samples Recommended: being a mosaicism should be studied tissue cells affected ..