SOTOS SYNDROME
FISH ANALYSIS

The Kleberg Cytogenetics Laboratory offers a fluorescence in situ hybridization (FISH)-based assay for identifying the microdeletion of the NSD1 gene (5q35) associated with Sotos syndrome.

Clinical Features:

Sotos syndrome is characterized by overgrowth in infancy and early childhood, dysmorphic facial features, advanced bone age and developmental delay. The dysmorphic features typically include macrocephaly, frontal bossing, prominent jaw and down-slanting palpebral fissures. The phenotype is variable, with some individuals having major cardiac, central nervous system and urinary system anomalies. Sotos syndrome is presumed to be autosomal dominant, with the majority of cases due to new mutations.

Reasons for Referral:

Patients with clinical features suggestive of Sotos syndrome may be tested for microdeletions of NSD1 by FISH. Prenatal diagnosis may be performed if an affected family member has been studied in our laboratory and shown to have a deletion detectable by FISH. Please call regarding all prenatal samples.

Testing Methodology:

FISH is the application of fluorescently labeled DNA molecules to metaphase chromosomes and interphase nuclei for the detection of chromosome abnormalities and alterations. It is a rapid, reliable and direct approach for identifying patients with microdeletions or microduplications. FISH analysis for Sotos syndrome is performed on metaphase chromosomes using the probe RP11-118M12. The presence of a single hybridization signal indicates a deletion. Microdeletions of 5q35, including the NSD1 gene, were reported in 19 of 38 affected individuals (Kurotaki et al) in a Japanese population. Deletions were observed in only a minority of patients studied in the UK (Douglas et al). Therefore, if FISH is negative, further molecular testing may be indicated in patients with a clinical diagnosis of Sotos syndrome.

Specimen Requirements:

Whole blood in sodium heparin (green-top) tubes:
Newborn (< 3 months): Minimum 0.5 -2.0 CC
Adult/Child: Minimum 3.0 -5.0 CC

Shipping and Handling:

All tubes must be labeled with the patient's testname and date of birth, and a completed requisition form must accompany each sample. If the laboratory is billing the patient's insurance, please enclose a copy of the insurance card. Ship specimens for overnight delivery at ambient temperature. Please notify the laboratory of incoming samples.

Turnaround Time:

7-10 days

CPT Codes and Prices:

88230, 88271, 88273, 88291

References:

1. Kurotaki, et al. (2002) Nat. Genet. 30: 365-366.
2. Douglas, et al. (2003) Am. J. Hum. Genet. 72: 132-143.
3. Nagai, et al. (2003) J. Med. Genet. 40: 285-289.

Forms:

>> Cytogenetics Requisition
>> Prenatal Requisition

Test Code:

8479