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CAT22
81129
unequivocal determination, whether the observed changes are located within a potentially
transcriptionally active genetic segment.
Useful For: Third-tier confirmatory testing of positive congenital adrenal hyperplasia (CAH) newborn
screens An adjunct to measurement of basal and adrenocorticotropic hormone-1-24-stimulated
17-hydroxyprogesterone, androstenedione, and other adrenal steroid levels in the diagnosis of atypical or
nonclassical cases of CAH Carrier detection of CYP21A2 mutations and genetic counseling An adjunct to
measurement of amniotic fluid 17-hydroxyprogesterone and androstenedione measurements in the
antenatal diagnosis of 21-hydroxylase deficiency
Interpretation: All detected alterations will be evaluated according to American College of Medical
Genetics and Genomics (ACMG) recommendations (Genet Med 2008:10[4]:294-300). Variants will be
classified based on known, predicted, or possible pathogenicity and reported with interpretive comments
detailing their potential or known significance.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Collett-Solberg PF: Congenital adrenal hyperplasias: from clinical genetics
and biochemistry to clinical practice, part I. Clin Pediatr 2001;40:1-16 2. Mercke DP, Bornstein SR, Avila
NA, Chrousos GP: NIH conference: future directions in the study and management of congenital adrenal
hyperplasia due to 21-hydroxylase deficiency. Ann Intern Med 2002;136:320-334 3. Speiser PW, White
PC: Medical progress: congenital adrenal hyperplasia. N Engl J Med 2003;349:776-788
22q11.2 Deletion/Duplication, FISH
Clinical Information: The 22q deletion syndrome and 22q duplication syndrome have overlapping
phenotypes. Deletions of 22q are associated with DiGeorge and velocardiofacial syndrome. These
syndromes are manifested by the presence of growth deficiency, global developmental delay, heart defect,
and hearing loss. The major birth defects include palatal clefting or insufficiency and thymus aplasia.
Prominent facial features are widely spread eyes, superior placement of eyebrows, downward slanting
palpebral fissures with or without ptosis (droopy upper eyelid), mild micrognathia (small jaw), and a long,
narrow face. FISH studies are highly specific and do not exclude other chromosome abnormalities. For
this reason, we recommend that patients suspected of having 22q deletion or duplication syndrome also
have conventional chromosome studies (CMS/8696 Chromosome Analysis, for Congenital Disorders,
Blood) performed to rule out other chromosome abnormalities or translocations.
Useful For: Aids in the diagnosis of 22q deletion/duplication syndromes, in conjunction with
CMS/8696 Chromosome Analysis, for Congenital Disorders, Blood Detecting cryptic translocations
involving 22q11.2 that are not demonstrated by conventional chromosome studies
Interpretation: Any individual with a normal signal pattern in each metaphase is considered negative
for this probe. Any patient with a FISH signal pattern indicating loss of the critical region (1 signal) will
be reported as having a deletion of the region tested by this probe. This is consistent with a diagnosis of
22q deletion syndrome. Any patient with a FISH signal pattern indicating duplication of the critical region
(3 signals) will be reported as having a duplication of the region tested by this probe. This is consistent
with a diagnosis 22q duplication syndrome.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Ensenauer RE, Adeyinka A, Flynn HC, et al: Microduplication 22q11.2 an
emerging syndrome: clinical, cytogenetic and molecular analysis of thirteen patients. Am J Hum Genet
2003;73:1027-1040 2. Yobb TM, Sommerville MJ, Willatt L, et al: Microduplication and triplication of
22q11.2: a highly variable syndrome. Am J Hum Genet 2005;76:865-876 3. Bassett AS, Chow EWC,
Husted J, et al: Clinical features of 78 adults with 22q11 deletion syndrome. Am J Med Genet
2005;138A:307-313 4. Manji A, Roberson JR, Wiktor A, et al: Prenatal diagnosis of 22q11.2 deletion
when ultrasound examination reveals a heart defect. Genet Med 2001;3:65-66
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