18p-

Genetic disorder involving deletion of part of chromosome 18

18p- is a genetic disorder caused by the deletion of all or part of the short arm (p arm) of chromosome 18. This condition is part of a group of chromosomal deletion syndromes that can lead to a variety of developmental and physical abnormalities. The severity and specific symptoms of 18p- can vary widely among affected individuals.

Genetics

Cebocephaly, a possible feature of 18p-

The human genome consists of 23 pairs of chromosomes, each containing a long arm (q arm) and a short arm (p arm). In individuals with 18p-, there is a deletion of genetic material from the p arm of chromosome 18. The size of the deletion can vary, and this variation can influence the severity of the symptoms.

The deletion can occur de novo, meaning it is a new mutation that occurs during the formation of reproductive cells or in early fetal development. In some cases, the deletion may be inherited from a parent who carries a balanced translocation involving chromosome 18.

Symptoms

The symptoms of 18p- can be diverse and may include:

• Developmental delay and intellectual disability
• Distinctive facial features, such as a flat nasal bridge, epicanthal folds, and a high-arched palate
• Cebocephaly, a condition characterized by a single nostril and closely set eyes
• Hearing loss
• Growth retardation
• Hypotonia (low muscle tone)
• Congenital heart defects

The presence and severity of these symptoms can vary significantly among individuals with 18p-.

Diagnosis

Diagnosis of 18p- is typically made through genetic testing. Karyotyping can reveal the deletion of the p arm of chromosome 18. More precise techniques, such as fluorescence in situ hybridization (FISH) or chromosomal microarray analysis, can be used to determine the exact size and location of the deletion.

Management

There is no cure for 18p-, but management of the condition focuses on addressing the specific symptoms and improving the quality of life for affected individuals. This may include:

• Early intervention programs to address developmental delays
• Special education services
• Speech, occupational, and physical therapy
• Regular monitoring and treatment of associated medical conditions, such as heart defects or hearing loss

Prognosis

The prognosis for individuals with 18p- varies depending on the size of the deletion and the severity of the symptoms. With appropriate medical care and support, many individuals with 18p- can lead fulfilling lives.

Related pages

• Chromosomal deletion syndrome
• Chromosome 18
• Genetic disorder