What is Minicore Myopathy?

Minicore Myopathy is an inherited condition catagorised by muscle weakness and wasting. In most cases the disease is Congenital (meaning from birth), but some people unfortunitely don't get a diagnosis until much later. It affects the skeletal muscles primarily and it has been found the muscles closest to the body are usually the most severely affected.


To truly understand how Minicore Myopathy impacts a persons life you first have to go back to the basic anatomy of the body. Our muscles not only enable us to lift heavy objects but support our bodys posture on a daily basis. Our muscles play a vital role in keeping us sitting and standing straight, keeping joints from dislocating, to put weight through our legs and help co-ordinate walking,, to grip a pencil significantly enough to write as well as even more basic living functions such as eye movement, pumping blood around our bodies via the heart and breathing. 

Minicore Myopathy is an extremely rare muscle condition and falls into the catagory of the Congenital Myopathies, a rare group of muscle weakening and wasting disorders that have similar characteristics aka "Myopathic Features" but otherwise are seperated by progression course and different gene mutations despite symptom similarities. Minicore was only first identified as one of the Congenital Myopathies in 1971 by Dr Engel and was originally called Multicore Myopathy or Multicore Disease. In 1974 the term was changed to Minicore Myopathy as it's prefered name.

Approximately only 2,000  cases have been documented worldwide. 

Myopathic Features Include (but are not limited to); Hypotonia - low muscle tone, floppiness, clubfoot/other foot deformities, cleft lip or palate, high arched palate, long face, facial muscle weakness resulting a "listless" expression, developement of Scoliosis and/ breathing problems, significantly weak neck, hyperflexibility OR rigidness, failure to thrive, lack of muscle bulk, waddling gait and a typical W sit.

Please see the Types section of  About Minicore Myopathy for specific symptoms related to Minicore Myopathy.

It has been debated for years over whether Minicore Myopathy is non-progressive or progressive. Old literature indicated it as being a non-progressive/static illness and may even show improvement with time. Todays literature shows Minicore Myopathy can be static, show slight improvement/stability in adulthood or can slowly . It is IMPORTANT to know that no two people with this condition will be exactly the same despite having the same diagnosis. Minicore Myopathy is extremely variable from person to person.

Four types of Minicore have been documented since 2004. They are;

Classic Form (75%)

Progressive Form With Hand Involvement (less than 10%)

Antenatal form with Arthrogryposis Multiplex Congenita (less than 10%)

Ophthalmoplegic Form (2%)

Click HERE to learn more about the types

Although specific types have been identified some people with a diagnosis of Minicore Myopathy do not fall into any of these four catagories or seem to have symptoms that fall into more than one form. Researchers are still trying to identify ALL the forms of Minicore and the gene mutations that cause them. 

A discovery was made in 2008 that idenfied a condition known as Rigid Spine Muscular Dystrophy (RSMD) aka Rigid Spine Syndrome was actually the "Classic" form of Minicore Myopathy when muscle biopsies were viewed of patients with RSMD and core structures were seen under the microscope.

What does this mean? The  percentage of people diagnosed with Minicore may be actually greater than first realized. It has not been documented yet how much the percentage has risen by but we expect it to be documented within the next couple of years. Due to RSMD being thought of as a separate illness it has given researchers some more clues as to what is going on genetically. It was the discovery that this condition was actually Minicore Myopathy that gave us another known gene mutation of SEPN1. You can find out more about the genetics of Minicore on our  What Causes Minicore Myopathy? page.