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Microdeletion Syndrome Detection

Fluorescence in situ Hybridization (FISH)

Microdeletion syndromes affect every pediatric and genetics practice. The incidence of these syndromes ranges from 1 in 50,000 to 1 in 8000. Diagnosis can be complicated by a negative family history and seemingly normal routine chromosome analysis. LabCorp continues its leadership in the field of diagnostic genetics by making available high-resolution chromosome analysis and FISH for many microdeletion syndromes. A partial listing of available tests follows.

 

Syndrome

Locus

Clinical Features

Probe

% Detectable*

*Deletion detected in those cases that have met strict diagnostic criteria.

**FISH performed as a follow-up to a positive RT-PCR test to determine mode of inheritance (test 511210).

Androgen insensitivity syndrome1

Xq11-q12

Androgen insensitivity (testicular feminization)

AR

Rare/unknown

Angelman syndrome2,3

15q11.2

Ataxic gait, inappropriate laughter, mental retardation

D15S10

80%

(uniparental disomy in <5%)

Cri-du-chat syndrome4

5p15.2

Characteristic cry, microcephaly, mental retardation

D5S23

NA

DiGeorge syndrome3,5,6

22q11.2

Dysmorphic features, hypoplasia/aplasia of thymus and parathyroid

HIRA (TUPLE1)

>90%

Isolated lissencephaly7

17p13.3

Lissencephaly

LIS1

~40%

Kallmann syndrome3,8

Xp22.3

Hypogonadism, anosmia/hyposmia, obesity, mental retardation, short stature, renal abnormalities, cryptorchidism, ataxia/synkinesis

KAL

NA

Miller-Dieker syndrome3

17p13.3

Mental retardation, dysmorphic features, seizures

LIS1

≥90%

Prader-Willi syndrome**3

15q11.2

Infant hypotonia, mental retardation, hypogonadism, obesity

SNRPN / DI5S10

70%

(uniparental disomy in 25%)

1pter deletion syndrome9

1p36

Dysmorphic features, hypotonia, psychomotor retardation, poor/absent speech

LSI p58

≥95%

PTEN Hamartoma tumor syndrome10

10q23

Includes Bannayan-Riley syndrome, Cowden syndrome, Proteus and Proteus-like syndromes

PTEN

11% for Bannayan-Riley syndrome

Short stature (short stature and Léri-Weill dyschondrosteosis)11,12

Xp22.3

(SHOX)

Short stature, microcephaly, hearing loss, cataracts, nasal hypoplasia, depressed nasal bridge, hypogonadism, skeletal anomalies, developmental delay

SHOX

2%-7%

Smith-Magenis syndrome3,13

17p11.2

Mental retardation, self-destructive behavior, craniofacial changes, sleep disturbances

FLI1

>99%

Soto syndrome14-17

5q35

(NSDI)

Cardinal (>90%): Characteristic facial features, learning disabilities, overgrowth. Major (15% to 89%): Behavioral problems, advanced bone age, cardiac abnormal, cranial MRI abnormal, renal, scoliosis, seizures

NSDI

50% of individuals of Japanese heritage and 10% of individuals of non-Japanese heritage have a 5q35 microdeletion that encompasses NSDI

Steroid sulfatase deficiency and X-linked ichthyosis3

Xp22.3

Absence of STS activity; ichthyosis of extensor and flexor extremities, face, and neck; possible cryptorchidism; corneal opacities, testicular cancer

STS

85%

Velocardiofacial syndrome6

22q11.2

Cleft palate, cardiac defect, developmental delay

HIRA (TUPLE1)

85%

Williams syndrome18,19

7q11.23

Dysmorphic features, cardiac defect, mental retardation, outgoing personality

ELN / LIMK

≥95%

Wolf-Hirschhorn syndrome20

4p16.3

Mental retardation, characteristic facies, psychomotor retardation

D4S96

NA

References

1. Gottlieb B, Beitel LK, Trifiro MA. Androgen sensitivity syndrome. GeneTests.www.genetests.org.Accessed November 15, 2011.

2. Buxton J, Chan C, Gilbert H, et al. Angelman syndrome associated with a maternal 15q11-13 deletion of less than 200 kb. Hum Mol Genet. 1994; 3(8):1409-1413. PubMed 7987324

3. Ledbetter D, Ballabio A. Molecular cytogenetics of contiguous gene syndromes: Mechanisms and consequences of gene dosage imbalance. In Scriver C, Beaudet A, Sly W, et al, eds.The Metabolic and Molecular Bases of Inherited Disease. 7th ed. New York, NY: McGraw-Hill; 1995:811-839.

4. Overhauser J, Huang X, Gersh M, et al. Molecular and phenotypic mapping of the short arm of chromosome 5: Sublocalization of the critical region for the cri-du-chat syndrome. Hum Mol Genet.1994; 3(2):247-252. PubMed 8004090

5. Driscoll D, Budarf M, Emanuel B, et al. A genetic etiology for DiGeorge syndrome: Consistent deletions and microdeletions of 22q11. Am J Hum Genet. 1992; 50(5):924-933. PubMed 1349199

6. Goldmuntz E, Emanuel B. Genetic disorders of cardiac morphogenesis. The DiGeorge and velocardiofacial syndromes. Circ Res. 1997; 80(4):437-443. PubMed 9118473

7. Pilz D, Macha M, Precht K, et al. Fluorescence in situ hybridization analysis with LIS1 specific probes reveals a high deletion mutation rate in isolated lissencephaly sequence. Genet Med. 1998; 1(1):29-33. PubMed 11261426

8. Rugarli E, Ballabio A. Kallmann syndrome. From genetics to neurobiology. JAMA. 1993; 270(22):2713-2715. PubMed 8133589

9. Battaglia A, Shaffer LG. 1p36 deletion syndrome. GeneTests.www.genetests.org. Accessed November 15, 2011.

10. Eng C. PTEN hamartoma tumor syndrome (PHTS). GeneTests.www.genetests.org. Accessed November 15, 2011.

11. Rappold GA, Fukami M, Niesler B, et al. Deletions of the Homeobox gene SHOX (short stature Homeobox) are an important cause of growth failure in children with short stature. J Clin Endocrinol Metab. 2002; 87(3):1402-1406. PubMed 11889216

12. Morizio E, Stuppia L, Gatta V, et al. Deletion of the SHOX gene in patients with short stature of unknown cause. Am J Med Genet A. 2003; 119A(3):293-296. PubMed 12784295

13. Moncla A, Piras L, Arbex OF, et al. Physical mapping of microdeletions of the chromosome 17 short arm associated with Smith-Magenis syndrome. Hum Genet. 1993; 90(6):657-660. PubMed 8444473

14. Allanson JE, Cole TR. Sotos syndrome: Evolution of facial phenotype subjective and objective assessment. Am J Med Genet. 1996; 65(1):13-20. PubMed 8914735

15. Tatton-Brown K, Rahman N. Clinical features of NSD1-positive Sotos syndrome. Clin Dysmorphol.2004; 13(4):199-204. PubMed 15365454

16. Kurotaki N, Harada N, Shimokawa O, et al. Fifty microdeletions among 112 cases of Sotos syndrome: Low copy repeats possibly mediate the common deletion. Hum Mutat. 2003; 22(5):378-387. PubMed 14517949

17. Tatton-Brown K, Douglas J, Coleman K, et al. Genotype-Phenotype associations in Sotos syndrome: An analysis of 266 individuals with NSD1 aberrations. Am J Hum Genet. 2005; 77(2):193-204.

18. Ewart A, Morris C, Atkinson D, et al. Hemizygosity at the elastin locus in a developmental disorder, Williams syndrome. Nat Genet. 1993; 5(1):11-16. PubMed 7693128

19. Osborne L. Williams-Beuren syndrome: Unraveling the mysteries of a microdeletion disorder. Mol Genet Metab. 1999; 67(1):1-10. PubMed 10329018

20. Altherr M, Wright T, Denison K, et al. Delimiting the Wolf-Hirschhorn syndrome critical region to 750 kilobase pairs. Am J Med Genet. 1997; 71(1):47-53. PubMed 9215768

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