SCIENTIFIC BACKGROUND

GBA

SCIENTIFIC BACKGROUND

Gaucher disease is an autosomal recessive disorder of the glycosphingolipid catabolism caused by reduced or absent activity of the lysosomal enzyme β-glucocerebrosidase (GBA). Pathogenic variants in the GBA gene are causative. The enzyme defect leads to progressive systemic accumulation of glucocerebroside (glucosylceramide) or glucosylsphingosine predominantly in the lysosomes of macrophages. With increasing storage, the macrophages increase in size and become so-called Gaucher cells, which can be detected predominantly in the spleen, liver, and bone marrow and are characteristic of the clinical picture.

 

In Gaucher disease, a differentiation is made between the non-neuronopathic and neuronopathic forms of the disease progression. The non-neuronopathic form (classic type I) shows a chronic course with hepatosplenomegaly, hematological changes, and bone involvement without neurological symptoms. This type is the most common accounting for 95%, although disease onset and clinical expression are variable. The neuronopathic form can be acute or chronic. The acute neuronopathic form (classic type II) is characterized by severe neurologic complications that usually lead to death within the first two years of life. The chronic neuronopathic type (classic type III) differentiates from the acute form by a later onset of the disease and a lower progression, and is usually associated with marked hepatosplenomegaly and severe bone involvement.

 

Two treatment strategies are available for the management of Gaucher disease. Enzyme replacement therapy (ERT) involves intravenous administration of the recombinant enzyme, which degrades glucocerebrosides stored in Gaucher cells. Alternatively, substrate reduction therapy (SRT) is available, which reduces the rate of synthesis of glucocerebroside, thereby preventing its accumulation. Substrate reduction therapy with the active ingredient eliglustat is designed for the long-term treatment of adult patients with Gaucher type I disease. The efficacy of eliglustat depends on the CYP2D6 metabolizer status of the patient. Therefore, determination of CYP2D6 metabolizer type should be performed prior to initiation of therapy (Cerdelga SmPC).

 

Direct measurement of β-glucocerebrosidase activity in leukocytes should be performed prior to molecular genetic testing of the GBA gene (ACMG Practice Guideline 2011).

 

References

Scott 2015, Drugs 75:1669 / Nagral 2014, J Clin Exp Hepatol 4:37 / Cassinerio et al. 2013, Eur J Intern Med. 25:117 / Grabowski 2012, Hematology Am Soc Hematol Educ Program 13 / Karaca et al. 2012, J Pediatr Endocr Met 25:957 / ACMG Practice Guideline, Wang et al. 2011, Genetics IN Medicine 13:457 / Bodamer et Hung 2010, Wien Med Wochenschr 160:600

GENES
GBA
ASSOCIATED TESTS
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