Infantile systemic hyalinosis: A genetic disorder characterized at birth or soon afterwards by painful swollen joint contractures and red pigmentation over bony prominences. Pearly papules (little bumps) and fleshy nodules then develop in the skin. Overgrowth of the gums and thickened skin are also characteristic. Children with the disease are susceptible to infections and intractable diarrhea. Hyaline (glassy) material is deposited in many tissues including the skin, muscle, the heart, gastrointestinal tract, lymph nodes, spleen, thyroid, and adrenal glands. The disease is inherited in an autosomal recessive manner. The gene for the disease is on chromosome 4q21.21. This gene encodes capillary morphogenesis protein 2 (CMG2 also known as ANTXR2 gene), a transmembrane protein that is induced during capillary morphogenesis. The same gene is mutated in juvenile hyaline fibromatosis, a similar but milder disease.