Laminopathies are a group of genetic disorders that are characterized by mutations in the lamins of cells of the human body. Over 250 different mutations have been known to occur in the lamins and these kinds of mutations can lead to the development of over fifteen different laminopathies. These conditions can be divided into several categories based on the symptoms and how they affect the human body.
Progeria is caused by two laminopathies: Atypical Werner syndrome and Hutchinson-Gilford progeria syndrome. The disorder itself is characterized by premature aging of a patient’s body. Bones become fragile, growth is limited, and many conditions may develop later on which include wrinkled skin, inflammation of arteries and heart problems. The condition of progeria is rather rare, but few children that develop it are able to survive past the age of thirteen.
Two different types of cardiomyopathy occur as a result of mutations in the lamin. These are hypertrophic cardiomyopathy and dilated cardiomyopathy. Hypertrophic consists of the thickening of heart muscles which makes it more difficult for blood to flow properly out of the heart. This forces the heart to work harder to get the same blood flow as a normal heart. Dilated consists of the enlargement of the heart which weakens the heart and limits the blood flow.
Laminopathies such as Greenberg dysplasia, Mandibuloacral dysplasia, Pelger-Huet anomaly, and Buschke-Ollendorff syndrome all cause one of three types of dysplasia. These types are dysplasia, Myelodysplastic syndrome, and skeletal dysplasia.
Normal dysplasia is characterized by the growth of immature cells in the body in place of more mature cells. This condition can be a precursor to tumor development. Myelodyplastic syndrome is a form dysplasia that specifically occurs with blood-forming cells. A patient will have more immature cells while the amount of functioning cells in the blood decreases. This can lead to a severe case of anemia and even a form of leukemia. Skeletal dysplasia is the abnormal growth of the connective tissue and bones. Legs, arms, torso, and the head can also form abnormally in terms of shape and size. This can lead to disproportionate limbs in relation to the rest of the body, which is commonly very short as a result of this condition.
As the names suggest, laminopathies like Limb-girdle muscular dystrophy and Emery-Dreifuss muscular dsystrophy cause two forms of muscular dystrophy. Emergy-Dreifuss causes cardiac muscular dystrophy, which is the weakening of the muscles in the heart. This typically requires patients to wear a pacemaker. Limb-girdle also causes muscular dystrophy but it is more prevalent in the shoulders and hips. This means that over time, the muscles in the shoulders and hips will weaken, which can greatly limit mobility.
Two laminopathies are associated with the condition of Lipodystrophy. These are Barraquer-Simons syndrome and mandibuloacral dysplasia. Lipodystrophy affects the fat distribution in the body, specifically in the face, neck, and back or upper torso. Lumps or even small depressions in the skin of these areas will appear as fat is either lost or gained in these areas. Typically the cheeks are sunken while the back of the neck or the back can develop of a hump.
Leukodystrophy is caused by the laminopathy Pelizaeus-Merzbacher disease. It is a condition that affects the development of myelin sheath in the skull. The white matter of the brain degenerates as a result of this problem with the sheath.