What is HIBM/IBM2?Hereditary Inclusion Body Myopathies (HIBM) are a group of muscle wasting disorders, which are uncommon in the general world population. An autosomal recessive form of HIBM is known as IBM2, which is a common genetic disorder amongst people of Iranian-Jewish descent. IBM2 has also been identified in other minorities throughout the world. Patients of Asian (Japanese and others), European, and South American origin, as well as Muslim patients in the Middle Eastern, Palestinian, and Iranian origin, have been identified. In Japan and many East Asian countries, this disorder is known as Distal Myopathy with Rimmed Vacuoles (DMRV).IBM2 causes progressive muscle weakness and wasting. Muscle wasting usually starts around the age of 20 - 30 years, although we have seen young onset at 17 and old onset at 52. As such, it affects the most productive times of our lives. It can progress to marked disability within 10 - 15 years, confining many patients to the wheelchair. The weakness and severity can vary from person to person. In some, weakness in the legs is noticed first. In few others, the hands are weakened more rapidly than the legs. Weakness is progressive, which means the muscle become weaker over time. IBM2 does not seem to affect the brain, internal organs or sensation. The quadriceps are relatively spared, and remain strong until the late stages of disease, which is the reason IBM2 is often referred to as Quadriceps Sparing Myopathy (QSM). Some early signs of H.I.B.M includes:
The most useful information for accurate diagnosis is the symptoms and weakness pattern. If the quadriceps are spared but the hamstrings and iliopsoas are severely affected in a person between ages of 20 - 40, it is very likely HIBM will be at the top of the differential diagnosis. The doctor may order any or all of the following tests to ascertain if a patient has IBM2:
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