Galactosemia



Test Description:

Classic galactosemia results from an enzymatic inability to break down the sugar galactose. As galactose is a major component of lactose, found in breast milk and formula, this disease will manifest in the neonatal period. If galactose is not removed from the diet, infants will develop lethargy and jaundice, feeding difficulties and will fail to gain weight. Sepsis and death may occur. With removal of galactose from the diet, affected children may still experience long-term complications, such as cataracts, developmental delay, or intellectual disability. Affected adult women may experience premature ovarian failure. Classic galactosemia is caused by mutations in the GALT gene. Individuals of Ashkenazi Jewish background have been found to carry a large 5.5 kb deletion, called c.-1039_+789del5573ins129. Testing for this mutation, as well as eight other mutations (c.253-2A&gtG, p.S135L, p.Q188R, p.T138M, p.F171S, p.L195P, p.Y209C, p.K285N), is expected to identify more than 95% of mutations in the Ashkenazi Jewish population, where the carrier frequency is about 1 in 156.

Full gene sequencing is available for reproductive partners of known mutation carriers. Prenatal diagnosis is also available. Prior to ordering prenatal testing, please contact our laboratory at 212-241-7518 to discuss.

References:

1. Elsas LJ 2nd, Lai K. The molecular biology of galactosemia. Genet Med. 1998 Nov-Dec1(1):40-8.
2. Goldstein N, Cohen Y, Pode-Shakked B, Sigalov E, Vilensky B, Peleg L, Anikster Y. The GALT rush: high carrier frequency of an unusual deletion mutation of the GALT gene in the Ashkenazi population. Mol Genet Metab. 2011 Feb102(2):157-60.
3. Coffee B, Hjelm LN, DeLorenzo A, Courtney EM, Yu C, Muralidharan K. Characterization of an unusual deletion of the galactose-1-phosphate uridyl transferase (GALT) gene. Genet Med. 2006 Oct8(10):635-40.



Specimen Requirements


Post-natal

Two 5-10 mL tubes of anticoagulated blood in EDTA (lavender top) or two 5-10 mL tubes of anticoagulated blood in ACD (yellow top).

Prenatal

Chorionic Villi: 5-10 mg in conical tube with sterile saline OR transport media
Amniotic Fluid: 10 ml in conical tube
Cultured Cells: Two confluent T-25 flasks

Additionally, please send:

5-10 ml maternal blood in EDTA (lavender top) required to perform MCC studies on all prenatal samples and in case maternal confirmation studies are necessary
5-10 ml paternal blood in EDTA (lavender top) in case paternal confirmation studies are necessary

Ordering Information


Shipping:

Ship at room temperature

Turnaround Time:

10 – 14 days

CPT Codes:

81401


Forms and Brochures


Carrier Screening Requisition and Consent [PDF]
Expanded Ashkenazi Jewish Carrier Screening Brochure [PDF]
Ashkenazi Jewish Carrier Screening Panel