Microdeletion Syndrome Detection

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

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