Partial deletion of the long arm of chromosome 1 syndrome

Partial deletion of the long arm of chromosome 1 syndrome (also referred to as 1q partial monosomy or partial monosomy 1q) is a rare chromosomal disorder caused by the loss of a segment of genetic material from the long arm (q arm) of chromosome 1. Because chromosome 1 is the largest human chromosome and contains a large number of genes, deletions of varying sizes and locations along 1q can produce a wide spectrum of clinical features. The specific signs and symptoms depend heavily on the size and precise location of the deleted segment. Common clinical features reported across different 1q deletions include intellectual disability of variable severity, developmental delay (particularly in speech and motor milestones), growth retardation, and distinctive craniofacial features such as microcephaly, a broad or prominent forehead, hypertelorism, low-set or malformed ears, and micrognathia. Congenital heart defects, skeletal anomalies, and genitourinary malformations may also be present. Some patients exhibit hypotonia, seizures, and behavioral difficulties. The phenotype is highly variable depending on the specific breakpoints involved. There is no cure for this chromosomal condition. Management is supportive and symptomatic, tailored to the individual's specific clinical manifestations. This may include early intervention programs, speech and occupational therapy, cardiac monitoring or surgical correction of heart defects, antiepileptic medications for seizures, and orthopedic management for skeletal abnormalities. Regular developmental assessments and multidisciplinary follow-up are recommended. Genetic counseling is important for affected families to understand recurrence risk, particularly if a parent carries a balanced chromosomal rearrangement.

Common questions about Partial deletion of the long arm of chromosome 1 syndrome