Small segmental deletions of chromosomes that are undetectable by high-resolution G-banding are called microdeletions. Microdeletions result in monosomy of the involved segment and cause clinically recognizable syndromes with variable population frequencies. These can be classified as interstitial, telomeric or subtelomeric according to the cytogenetic localization of the deleted segment, and the best known syndromes include velocardiofacial, Prader-Willi, Angelman, Williams, Smith-Magenis, and Wolf-Hirschhorn syndromes. However, 1p36 microdeletion syndrome, the most common among subtelomeric deletions causing intellectual disability, the recently described 9q34 deletion syndrome (Kleefstra syndrome), 22q13.3 deletion (Phelan-McDermid syndrome), which is estimated to be underdiagnosed owing to its rather non-specific features, and 15q13.3, 16p11.2 and 17q21.31 deletions, recently described using microarray techniques for genome-wide high-resolution screening, may cause practical difficulties in the practice of pediatrics. Clinical management of patients should include genetic counseling on the disease-causing mechanisms and risk of recurrence as well as disease-specific evaluation of manifestations.

Keywords: mikrodelesyon sendromları, submikroskopik, interstisyel, telomerik ve subtelomerik.