Krabbe disease


Description

Krabbe disease (MIM #245200) is an autosomal recessive inborn error of metabolism caused by deficiency of the enzyme galactosylceramidase (galactocerebrosidase). Galactosylceramidase (EC 3.2.1.46) is a lysosomal enzyme involved in the catabolism of galactosylceramide, a major lipid in myelin, kidney, and epithelial cells of the small intestine and colon. Enzyme deficiency results in the build-up of undigested fats affecting growth of the nerve�s protective myelin sheath and causes severe degeneration of mental and motor skills. The disease may be diagnosed by its characteristic grouping of certain cells (multinucleated globoid cells), nerve demyelination and degeneration, and destruction of brain cells. Special stains for myelin (e.g. luxol fast blue) may be used to aid diagnosis. Definitive testing is by direct enzyme analysis. Infants with Krabbe disease are normal at birth. Symptoms begin between the ages of 3 and 6 months with irritability, inexplicable crying, fevers, limb stiffness, seizures, feeding difficulties, vomiting, and slowing of mental and motor development. In infants, the disease is generally fatal before age 2. There are also juvenile- and adult-onset cases of Krabbe disease, which have similar symptoms but slower progression and significantly longer lifespan. Although there is no cure for Krabbe disease, bone marrow transplantation has been shown to benefit mild cases early in the course of the disease. The incidence of Krabbe disease is around 1 in 100,000�200,000 births. The GALC gene is situated at 14q31 and consists of 17 exons. A recurrent 30kb deletion has been described which extends from intron 10 to intron 17 of the GALC gene and in the homozygous state is associated with infantile onset disease. The allele frequency of this deletion in Krabbe patients is reported to be approximately 50% in Dutch patients and 35% in non-Dutch European patients (Kleijer, WJ et al. (1997) J Inher Metab Dis 20:587-594).

Also known as

Globoid cell leukodystrophy, galactocerebrosidase deficiency, GALC deficiency


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When requesting this test please use the referral form provided. Please also refer to any additional information provided for this test.


Additional information

Clinically affected patients should have their diagnosis confirmed by enzyme analysis; such patients may then be referred for mutation analysis. If the necessary patient samples are unavailable genetic testing can be undertaken in the parents of the affected child. Information regarding ethnic origin is useful. Testing for the common 30kb deletion by three-primer PCR analysis. Other disease causing mutations are heterogeneous and testing is not currently offered as part of this diagnostic service. Download additional information >


Sending address

Great Ormond Street Hospital NE Thames Regional Genetics Service Laboratories
Great Ormond Street Hospital for Children
Barclay House
37 Queen Square
London
WC1N 3BH

Laboratory service

Genetics


Sample requirements

1ml EDTA neonates, 5ml EDTA adults


Reference range

Not applicable


Turnaround time

10 days


Disease / group

GALC


Cost

Upon request


Call in advance?

Prenatals must be arranged in advance, through a Clinical Genetics department if possible.


Genetics

The Genetics Laboratories provide an extensive range of Cytogenetics and Molecular Genetics diagnostic testing services.

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