Juvenile hyaline fibromatosis: A genetic disorder characterized by multiple subcutaneous nodules and gingival hypertrophy (overgrowth of the gums) beginning in the first few years of life and, later, joint contractures. There are deposits of hyaline (glassy) material in the skin. The disease is inherited as an autosomal recessive condition. 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, CMG2, is mutated in infantile systemic hyalinosis, a similar but more severe disease.