Glomuvenous malformations (GVM) and Cutaneomucosal venous malformations (VMCM) - Glomuvenous malformations (GVM; MIM 138000) are a type of vascular malformation mainly involving the skin and subcutis of the extremities.  GVM are often present at birth and slowly expand.  Typically they are nodular, multifocal hyperkeratotic lesions with a cobble stone appearance.  They are often painful on palpation, pink to dark blue in color and cannot be emptied on compression.  These features distinguish GVM from typical venous malformation.   Histologically, GVM are characterized by distended vascular channels surrounded by mural glomus cells.  Glomus cells are considered to be abnormally differentiated vascular smooth muscle cells.  GVM are caused by loss of function mutations in the glomulin (GLMN) gene.  Although inheritance is considered to be autosomal dominant, some evidence suggests  that a 'second hit' somatic mutation (paradominant inheritance) is required for the lesions to develop.

Cutaneomucosal venous malformations (VMCM; MIM 600195) are inherited in autosomal dominant manner with incomplete penetrance. VMCM are characterized by small, soft, blue colored, multifocal venous malformations that can be seen at birth. Unlike the GVM, VMCM can be emptied by external pressure. The VMCM can involve skin and oral mucosa. VMCM are caused by mutations in the endothelial cell tyrosine kinase receptor gene (TEK, formerly known as TIE2).

Copy number variation (CNV) analysis of the Glomuvenous malformations and Cutaneomucosal venous malformationsgenes is also offered as a panel. Additionally, CTGT offers a comprehensive test (both NGS and CNV panels) for these genes. Panel genes are also offered as individual sequencing and deletion/duplication tests unless otherwise indicated.