Children with this type of ASMD rarely live beyond 18 months. It has a grim prognosis and no known cure. Additional symptoms include weakness, an enlarged liver and spleen, and swollen lymph nodes. Type A, the more severe form, occurs most often in Jewish families and involves damage to brain cells (neurons) it generally causes severe neurodegenerative symptoms during infancy. Acid Sphingomyelinase Deficiency (ASMD)ĪSMD has traditionally been broken down into two subgroups: neuronopathic (type A) and non-neuronopathic (type B). According to NINDS, affected individuals may be unable to look up and down, have difficulty in walking and swallowing, and have progressive loss of vision and hearing. ![]() ![]() The disease is fatal, with earlier diagnosis associated with more severe disease and a shorter life span. The symptoms of Neimann-Pick disease type C can appear around the time of birth, during infancy, in the childhood or teen years, or well into adulthood. In some cases, ASMD is a fatal neurodegenerative disorder that begins during infancy (Niemann-Pick disease type A), while in others, individuals experience minimal neurological symptoms and survive into adulthood (Niemann-Pick disease type B). There may be clouding of the cornea, and a characteristic cherry-red halo develops around the center of the retina. Other symptoms may include feeding and swallowing difficulties, eye paralysis, learning problems, and an enlarged liver and spleen. Symptoms of Niemann-Pick disease may include ataxia (lack of muscle control during voluntary movements such as walking), loss of muscle tone, brain degeneration, increased sensitivity to touch, spasticity (stiff muscles and awkward movement), and slurred speech, according to the National Institute of Neurological Disorders and Stroke (NINDS). There are also Niemann-Pick types C1 and C2, which are caused by mutations in the NPC1 and NPC2 genes. While each individual lysosomal storage disease is rare, collectively, they are common, according to StatPearls.Īcid sphingomyelinase deficiency refers to Niemann-Pick types A and B, which are associated with the SMPD1 gene. In lysosomal storage diseases, fats, proteins, and sugars that can’t be broken down correctly, usually because of missing or defective enzymes, are stored in lysosomes, resulting in damage to the organs in which these materials accumulate. ![]() Normally, tiny bodies within cells called lysosomes metabolize lipids, proteins, and carbohydrates into smaller components to provide energy for the body. Niemann-Pick disease is, in turn, one of a group of diseases known as lysosomal storage diseases. Lysosomal Storage DiseasesĪSMD is a subtype of Niemann-Pick disease, a group of inherited disorders in which lipids build up in the brain, spleen, liver, lungs, and bone marrow because of defective or insufficient amounts of the enzymes that normally break down those substances. The symptoms of ASMD can first appear during infancy or later in childhood, and its severity can vary dramatically from one person to another, sometimes even among members of the same family. It’s a major component of cell membranes, including the myelin sheath that surrounds and electrically insulates nerve cells, and also plays important roles in cellular transport, communication, and apoptosis, or programmed cell death.Īs sphingomyelin and other lipids accumulate in various tissues of the body, they can cause damage to several key organs, including the liver, spleen, lungs, and central nervous system (CNS), or the brain and spine. This enzyme is needed to break down (metabolize) a fatty substance (lipid) called sphingomyelin, which has significant structural and functional roles in the cell. ![]() Acid sphingomyelinase deficiency (ASMD) is a rare, progressive, inherited genetic disorder that’s caused by a deficiency in an enzyme called acid sphingomyelinase.
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