Difference Between Overlap Syndrome and Mixed Connective Tissue Disease

The key difference between Overlap Syndrome and Mixed Connective Tissue Disease is that the mixed connective tissue disease is one variety of the overlap syndrome. That is, the overlap syndrome is a special subgroup of connective tissue disorders, characterized by the presence of clinical features of more than one autoimmune rheumatic disease. On the other hand, the characteristic feature of mixed connective tissue disorder is the presence of clinical features corresponding to systemic sclerosis, SLE, rheumatoid arthritis, and polymyositis, along with an increase in the antibodies against ribonuclear proteins (U1 RNP).

Connective tissue disorders are one of the commonest causes of morbidity in the elderly people. Although the incidence and prevalence of these diseases are high among the elderly, they can affect the people of any age group.

CONTENTS

1. Overview and Key Difference
2. What is Overlap Syndrome
3. What is Mixed Connective Tissue Disease
4. Similarities Between Overlap Syndrome and Mixed Connective Tissue Disease
5. Side by Side Comparison – Overlap Syndrome vs Mixed Connective Tissue Disease in Tabular Form
6. Summary

What is the Overlap Syndrome?

The presence of features of more than one autoimmune rheumatic disease is known as the overlap syndrome. Therefore, usually, the patients have a mixed clinical picture with symptoms and signs of systemic sclerosis, rheumatic arthritis or SLE.

However, depending on the disease combination levels of different antigens can go up.

What is Mixed Connective Tissue Disease?

Mixed connective tissue disorder is characterized by the presence of clinical features corresponding to systemic sclerosis, SLE, rheumatoid arthritis and polymyositis along with an increase in the antibodies against ribonuclear proteins (U1 RNP).

Moreover, typically there is no renal or CNS involvement in this condition.

What is the Similarity Between Overlap Syndrome and Mixed Connective Tissue Disease?

• Both conditions are due to the defects in the connective tissue that make up the musculoskeletal system. However, they can have other systemic manifestations also depending on the diseases that occur together.

What is the Difference Between Overlap Syndrome and Mixed Connective Tissue Disease?

Overlap syndrome is a broad term that covers many situations where several autoimmune rheumatic diseases coexist whereas the mixed connective tissue disorder is one variety of the overlap syndrome. That is, the presence of features of more than one autoimmune rheumatic disease is known as the overlap syndrome. On the contrary, the mixed connective tissue disorder is characterized by the presence of clinical features corresponding to systemic sclerosis, SLE, rheumatoid arthritis and polymyositis along with an increase in the antibodies against ribonuclear proteins (U1 RNP). Below infographic presents more details on the differences between Overlap Syndrome and Mixed Connective Tissue Disease.

Summary – Overlap Syndrome vs Mixed Connective Tissue Disease

The presence of features of more than one autoimmune rheumatic disease is known as the overlap syndrome. Mixed connective tissue disorder, on the other hand, is characterized by the presence of clinical features corresponding to systemic sclerosis, SLE, rheumatoid arthritis and polymyositis along with an increase in the antibodies against ribonuclear proteins (U1 RNP). Going by the definition of the overlap syndrome, the mixed connective tissue is a variety of overlap syndrome rather than a separate disease. This is the main difference between Overlap Syndrome and Mixed Connective Tissue Disease.

Reference:

1.Parveen Kumar. Kumar and Clark’s Clinical Medicine. Edited by Michael L Clark, 8th ed.

Image Courtesy:

1.’1691868′ by WolfBlur (CC0) via pixabay
2.’30956691112′ by Daniel Max (CC BY 2.0) via Flickr