About infantile gaucher disease
What is infantile gaucher disease?
Gaucher disease is a rare, inherited metabolic disorder in which deficiency of the enzyme glucocerebrosidase results in the accumulation of harmful quantities of certain fats (lipids), specifically the glycolipid glucocerebroside, throughout the body especially within the bone marrow, spleen and liver. The symptoms and physical findings associated with Gaucher disease vary greatly from case to case. Some individuals will develop few or no symptoms (asymptomatic); others may have serious complications. Common manifestations of Gaucher disease include an abnormally enlarged liver and/or spleen (hepatosplenomegaly), low levels of circulating red blood cells (anemia), low levels of platelets(thrombocytopenia), and skeletal abnormalities. Platelets are blood cells that promote clotting and patients with thrombocytopenia may develop bleeding problems. Three separate forms of Gaucher disease have been identified and are distinguished by the absence of, or the presence and extent of, neurological complications. All three forms of Gaucher disease are inherited as autosomal recessive traits.
Gaucher disease is categorized as a lysosomal storage disorder. Lysosomes are the major digestive units in cells. Enzymes within lysosomes break down or "digest" nutrients, including certain complex carbohydrates and fats. In Gaucher disease certain sugar (glucose) containing fat, known as glycolipids, abnormally accumulate in the body because of the lack of the enzyme, glucocerebrosidase. This accumulation or "storage" of lipids leads to the various symptoms or physical findings associated with a lysosomal storage disease. Gaucher disease is the most common type of lysosomal storage disorder.
What are the symptoms for infantile gaucher disease?
Researchers have identified three distinct forms of Gaucher disease separated by the absence (type 1) or presence and extent (type 2 or type 3) of neurological complications. Additional forms of Gaucher disease include perinatal-lethal form and cardiovascular form. The specific symptoms present in individuals with Gaucher disease vary greatly from person to person. Some individuals exhibit few or no symptoms (asymptomatic); others experience chronic, and sometimes severe, complications.
Gaucher disease type 1 is also known as non-neuronopathic, because it does not involve the central nervous system (brain and spinal cord). Type 1 Gaucher disease is the most common form of the condition. Most individuals with Gaucher disease type 1 experience easy bruising due to low levels of blood clotting cells known as platelets (thrombocytopenia), chronic Fatigue due to low levels of circulating red blood cells (anemia), and an abnormally enlarged liver and/or spleen (hepatosplenomegaly). Affected individuals may also experience lack of blood supply (infarction) to various bones of the body resulting in dull or intense bone Pain (bone crises), Degeneration (avascular necrosis) and deformity of affected bones, and thinning and weakening of bones (osteoporosis). Such skeletal abnormalities result in an increased susceptibility to fractures. In rare cases, affected individuals may also experience involvement of the lungs and/or kidneys.
Gaucher disease type 2, also known as acute neuronopathic Gaucher disease, occurs in newborns and infants and is characterized by neurological complications due to the abnormal accumulation of glucocerebroside in the brain. Enlargement of the spleen (splenomegaly) is often the first symptom and may become apparent before six months of age. Enlargement of the liver (hepatomegaly) is not always evident. Affected infants may lose previously acquired motor skills and exhibit Low muscle tone (hypotonia), involuntary Muscle spasms (spasticity) that result in slow, stiff movements of the arms and legs, and crossed eyes (strabismus). In addition, affected infants may experience Difficulty swallowing (dysphagia), which may result in feeding difficulties; abnormal positioning or bending of the neck (retroflexion); and failure to gain weight and grow at the expected rate (failure to thrive) and high-pitched breathing (stridor) due to contraction of the muscles of the voice box (laryngeal spasm). Anemia and thrombocytopenia may also occur. Gaucher disease type 2 often progresses to life-threatening complications such as respiratory distress or the entrance of food into the respiratory passages (aspiration pneumonia). Severely affected newborns may show skin abnormalities (collodion skin or ichthvosiform changes) and generalized swelling (hydrops), with death in the first few weeks of life. Other children with Gaucher disease type 2 have greatly reduced lifespans, with death usually occurring between 1 and 3 years of life.
Gaucher disease type 3, also known as chronic neuronopathic Gaucher disease, occurs during the first decade of life. In addition to the blood and bone abnormalities discussed above, affected individuals develop neurological complications that develop and progress slower than in Gaucher disease type 2. Associated neurological complications include mental deterioration; an inability to coordinate voluntary movements (ataxia); and brief, shock-like Muscle spasms of the arms, legs or entire body (myoclonic seizures). Some individuals with Gaucher disease type 3 may have difficulty moving their eyes from side-to-side (horizontal gaze palsy). Patients with Type 3 Gaucher disease can also have a vertical gaze palsy that usually occurs later than the horizontal gaze paresis. A significant proportion of patients also develop pulmonary (lung) disease (interstitial lung disease). There can be wide variability in presentation and clinical course among patients with type 3 Gaucher disease. Some affected patients may live into their teens and early 20’s, while others have lived for much longer (30’s and 40’s). With increasing difficulties, affected individuals may require assistance to fulfill the task of daily living (for example, with eating, bathing, and ambulation).
The perinatal-lethal form or fetal/neonatal Gaucher disease occurs in less than 5% of patients. This type is very severe and associated with death before 3 months of age or even in the womb. The fetus/newborn may present with widespread swelling of the skin (edema or anasarca) leading to fluid buildup in the heart, skin, or lungs (hydrops fetalis). Other symptoms include bleeding within the skull (intracranial hemorrhage), scaling of the skin (non-bullous ichthyosiform erythrodema) with a reddish appearance, and contraction of the joints in fixed, bent position (arthrogryposis multiplex congenita).
The cardiovascular form is characterized by CNS involvement, such as having difficulty initiating eye movement in desired directions (oculomotor apraxia). Other symptoms include calcification of the mitral and aortic valve, corneal opacity, and mild splenomegaly. Calcium deposits on the heart can reduce blood flow to these valves, and can increase blood pressure. Supranuclear ophthalmoplegia can also be present, which causes problems with balance, walking, and thinking. Cardiac-related complications and associated neurologic problems lead to a reduced lifespan, although this can extend into young adulthood in some patients.
What are the causes for infantile gaucher disease?
Gaucher disease is caused by changes (mutations) in the GBA gene.
All three forms of Gaucher disease are inherited in an autosomal recessive pattern. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother.
Recessive genetic disorders occur when an individual inherits an abnormal gene from each parent. If an individual receives from each parent one normal gene and one abnormal gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the abnormal gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier, like the parents, is 50% with each pregnancy. The chance for a child to receive normal genes from both parents is 25%. The risk is the same for males and females.
What are the treatments for infantile gaucher disease?
The main goal is to improve the patients’ quality of life by allowing them to perform their normal daily activities, such as working without feeling the excess fatigue or walking normally without experiencing joint pain. Other goals include preventing the severity of complications, such as reduced bone density to thinning, weak bones (osteoporosis) and easy fractures or shortness of breath from the reduced lung function. Normalizing the growth for a child for them to reach a normal height can also be a target within a couple of years of treatment and achieving a normal onset of puberty.
Treatment is individualized for each patient depending on the type of Gaucher disease. Type 1 Gaucher disease is considered treatable and mild, because it does not involve neurological symptoms since the brain is not affected. Type 2 is not considered to be treatable at this point due to the quick and irreversible brain damage in the infantile years. Type 3 still involves neurological damage, but these symptoms progress more slowly than in type 2. There are current FDA-approved drug therapy options that include enzyme replacement therapy (ERT) and substrate reduction therapy (SRT).
ERT is given every 2 weeks via intravenous (IV) infusions either at infusion centers, National Gaucher Disease Treatment Center, or at home by self-administration, assistance from a family member/friend or home care nurse. The three current FDA-approved ERT drugs include imiglucerase (Cerezyme), velaglucerase alfa (VPRIV), and taliglucerase (Elelyso).
Genetic counseling is recommended for affected individuals and their families. Other treatment is symptomatic and supportive.
There is current research at the Medical Genetics Branch of the National Human Genome Research Institute about a possible link or association between Gaucher disease and Parkinson disease. Studies have shown that affected individuals (with two disease-causing GBA gene mutations) and carriers (with a single GBA gene mutation) both have an increased risk of Parkinson disease.
Individuals with Gaucher disease are at increased risk for multiple myeloma, and as adults should be monitored carefully.
What are the risk factors for infantile gaucher disease?
All forms of Gaucher disease affect males and females in equal numbers. Gaucher disease type 1 is the most common type, accounting for more than 90 percent of cases among Caucasians. Individuals with Gaucher disease type 1 usually exhibit symptoms during adolescence, but the age of onset ranges from childhood to adulthood. The age of onset for Gaucher disease type 2 is during early infancy. The age of onset of Gaucher disease type 3 varies, but the disorder generally begins during childhood or adolescence. The frequency of neuropathic forms of Gaucher disease, that is, the proportion of such cases, is higher among non-Caucasians.
There are approximately 6,000 individuals with Gaucher disease in the United States. Gaucher disease is the most common genetic disorder of persons of Ashkenazic Jewish ancestry, where the incidence may be as high as 1 in 450 births. There is no ethnic prevalence associated with Gaucher disease types 2 or 3. However, there is a subtype of Gaucher disease type 3 that occurs with greater frequency in the Norrbotten region of Sweden (Norrbottnian Gaucher disease). The estimated prevalence in the Swedish Norrbotten population is 1 in 50,000.
Is there a cure/medications for infantile gaucher disease?
Enzyme replacement therapy (ERT) has proven effective for individuals with Gaucher disease type 1. In studies of ERT, anemia and low platelet counts have improved, enlargement of the liver and spleen have been greatly reduced, and skeletal findings have improved. These systemic manifestations also improve in individuals with Gaucher disease types 2 and 3 who receive ERT. However, ERT has not been effective in reducing or reversing certain neurological symptoms associated with Gaucher disease types 2 and 3.
The orphan drug alglucerase injection (Ceredase), which is a placenta-derived enzyme, was approved by the U.S. Food and Drug Administration (FDA) in 1991 for the treatment of Gaucher disease type 1. It was the first ERT proven effective for the treatment of Gaucher disease type 1.
The synthetic form of this drug, imiglucerase (Cerezyme), was approved in 1994. Recombinant DNA technology, or genetic engineering, is used to produce Cerezyme. This was an important step in overcoming limitations of the availability of Ceredase, which is derived from human placentas. Therefore, Ceredase has been withdrawn from the market due to similar drugs being made without having bioavailability issues from human derived cells and the transfer of diseases. Cerezyme, manufactured by Genzyme, replaces the human lysosomal enzyme glucocerebrosidase that is lacking in individuals with Gaucher disease.
Another FDA approved preparation of glucocerebrosidase called Velaglucerase alfa (trade name VPRIV) produced in a continuous human cell line is available from Shire.
Elelyso (also known as Uplyso or taliglucerase alfa) by Pfizer Inc., under license from Protalix BioTherapeutics Inc., was approved by the FDA in 2012 as a treatment for Gaucher disease type 1. Elelyso is an injected long-term enzyme replacement therapy that should be administered by a health care professional every other week. It uses genetically engineered carrot cells to provide replacement glucocerebrosidase.
Substrate reduction therapy may also be utilized in specific patient populations. These work differently than the ERT’s by blocking the production of glucocerebroside (fatty substance) by inhibiting the enzyme glucosylceramide synthase. These come in tablets/capsules and are taken daily. SRT’s are not to be used in children and teenagers, pregnant or breastfeeding women, elderly patients, and people with severe kidney or liver disease. The two current FDA-approved drugs include eliglustat (Cerdelga) and imiglustat (Zavesca).
In 2014, Cerdelga (eliglustat), manufactured by Genzyme, was approved by the FDA for the long-term treatment of adult patients with the Gaucher disease type 1.
In 2003, the U.S. Food and Drug Administration approved Zavesca, an oral therapy, for the treatment of adult patients with mild to moderate Gaucher disease type 1 for whom enzyme replacement therapy is not a treatment option (as a result of allergy, hypersensitivity, etc.).