Microdeletion Analysis (Other)

It is standard of care to diagnose microdeletion syndromes using fluorescence in situ hybridization (FISH).

Other specimen types may be appropriate for testing. Call a laboratory genetic coordinator prior to obtaining specimens.

Fluorescence in situ hybridization (FISH)

Angelman syndrome (AS) is characterized by severe developmental delay/mental retardation, absence of speech, ataxic gait, inappropriate laughter, hand-flapping and, less frequently, microcephaly and seizures. AS is not usually suspected in the first year of life, but becomes a consideration between 1-4 years of age. Cri-du-chat is characterized by dysmorphic facial features, microcephaly, growth deficiency, intellectual disability, speech delay and a characteristic “cat-like” cry. DiGeorge/Velocardiofacial syndromes are due to 22q11 .2 deletions. DiGeorge syndrome is a genetic disorder characterized by hypocalcemia, congenital heart defects, cleft lip and/or palate, microcephaly and mild intellectual disability. Velocardiofacial syndrome is characterized by facial abnormalities, congenital heart defects, diminished muscle tone, small stature, psychomotor disability and/or learning disabilities. Kallmann syndrome involves the hypothalamus, causing a hormone deficiency. Symptoms include: failure to enter puberty, lack of sexual drive, infertility (non-ovulation in women and azoospermia/oligospermia in men) and no sense of smell. Miller-Dieker syndrome is characterized by lissencephaly ("smooth brain"), mental retardation and a distinct facial appearance. Prader-Willi syndrome (PWS) is characterized by: hypotonia, failure to thrive in infancy, rapid weight gain/obesity between 12 months and 6 years, characteristic facial features, hypogonadism and mild to moderate intellectual disability. Smith-Magenis syndrome is characterized by flattened mid-face; down-turned mouth; hypotonia; short, broad hands; mental retardation; chronic sleep disturbance and self-injurious behavior. Steroid sulfatase deficiency (X-linked ichthyosis) has a variable presentation characterized by dry, scaly skin, sparse hair and conical teeth in affected males. Williams syndrome is a genetic disorder characterized by "elfin" facial features, intellectual disability, growth deficiency, hypercalcemia and cardiovascular disease. Wolf-Hirschhorn syndrome is characterized by microcephaly, growth deficiency, intellectual disability and characteristic facial features.