Microdeletion Analysis (Other)
88271(1), 88273(1), 88274(1) (plus appropriate tissue culture codes: 1 probe - 1 unit, 2 probes - 2 units, 3 probes - 3 units, 4 probes - 4 units, 5 probes - 5 units, 6 probes - 6 units) 88271(2), 88273(2), (for Angelman syndrome or Prader-Willi syndrome)
Microdeletion Syndrome Analysis, Fluorescence in situ Hybridization (FISH);
Other specimen types may be appropriate for testing. Call a laboratory genetic coordinator prior to obtaining specimens.
Adult: 5-10 mL / Child: 2-5 mL (less for newborn)
Green-top (sodium heparin) tube; fixed-cell pellet or slides/coverslips of fixed metaphase cell preparations
Maintain specimens at room temperature.
Causes for Rejection
Broken or dirty slides; excessive cellular debris; stains on slides
It is standard of care to diagnose microdeletion syndromes using fluorescence in situ hybridization (FISH).
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.