microdeleción

A microdeletion refers to the loss of a small segment of genetic material, typically involving a few to several hundred base pairs of DNA. Unlike larger chromosomal deletions, microdeletions occur at a microscopic level and are often not visible under standard cytogenetic analysis. They are a type of copy number variation (CNV), where a portion of the genome is either deleted or duplicated.

Microdeletions can arise spontaneously due to errors during DNA replication or meiosis, or they may be inherited from a parent. Some are associated with specific genetic syndromes, such as 22q11.2 deletion syndrome (also known as DiGeorge syndrome or velo-cardio-facial syndrome), which involves the deletion of a small region on chromosome 22. This condition can lead to a range of clinical features, including congenital heart defects, immune system abnormalities, and developmental delays.

Diagnosing microdeletions typically requires advanced molecular techniques, such as chromosomal microarray analysis (CMA) or next-generation sequencing (NGS). These methods detect imbalances in DNA copy number that may not be apparent through traditional karyotyping. Symptoms associated with microdeletions vary widely depending on which genes are affected and the extent of the deletion.

While some microdeletions have clear genetic links to recognizable syndromes, others may present with non-specific symptoms or remain asymptomatic. The clinical impact depends on the specific genes lost, as well as individual genetic background and environmental factors. Genetic counseling is often recommended for individuals with suspected microdeletions to discuss inheritance patterns, recurrence risks, and management options. Research into microdeletions continues to expand understanding of their role in human health and disease.