Partial deletion of the short arm of chromosome 18 syndrome

Partial deletion of the short arm of chromosome 18 syndrome, also known as 18p deletion syndrome or monosomy 18p, is a rare chromosomal disorder caused by the loss (deletion) of part of the short arm (p) of chromosome 18. The size and exact location of the deleted segment can vary among affected individuals, which contributes to a wide spectrum of clinical severity. This condition is typically characterized by mild to moderate intellectual disability, short stature, round face with a flat nasal bridge, wide mouth, and ptosis (drooping eyelids). Speech and language delays are common, and some individuals may also have holoprosencephaly (a brain malformation involving incomplete division of the forebrain) in more severe cases. Additional features may include muscular hypotonia (low muscle tone), skeletal anomalies, dental abnormalities, and occasional congenital heart defects. Some individuals develop autoimmune conditions, particularly IgA deficiency and thyroid disorders. Behavioral and emotional difficulties, including anxiety and attention problems, have also been reported. Growth hormone deficiency may contribute to short stature in some patients. There is no cure for 18p deletion syndrome, and management is supportive and symptom-based. Early intervention programs including speech therapy, physical therapy, and occupational therapy are important for optimizing developmental outcomes. Growth hormone therapy may be considered for individuals with documented growth hormone deficiency. Regular monitoring for autoimmune conditions, thyroid function, and cardiac anomalies is recommended. Surgical intervention may be necessary for congenital heart defects or other structural abnormalities. Genetic counseling is advised for affected families.

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