Pseudoxanthoma elasticum: clinical phenotypes, molecular genetics and putative pathomechanisms

Area of Science:

• Genetics
• Biochemistry
• Pathology

Background:

• Pseudoxanthoma elasticum (PXE) is a heritable disorder affecting skin, eyes, and cardiovascular system due to pathological mineralization.
• The ABCC6 gene, encoding an ABC transporter, was initially identified as the primary cause of PXE.
• Abcc6 knockout mice models exhibit connective tissue mineralization, confirming ABCC6's role.

Purpose of the Study:

• To investigate the genetic basis and pathomechanisms of Pseudoxanthoma elasticum (PXE).
• To explore the role of the GGCX gene and vitamin K-dependent carboxylation in PXE pathogenesis.
• To identify potential therapeutic strategies for PXE by understanding its molecular underpinnings.

Main Methods:

• Identification of loss-of-function mutations in the ABCC6 gene using streamlined mutation detection strategies.
• Analysis of patients with PXE-like symptoms and coagulation factor deficiency, including genetic testing for GGCX mutations.
• Utilizing knockout mouse models (Abcc6-/-) to study connective tissue mineralization.

Main Results:

• Over 300 distinct ABCC6 loss-of-function mutations have been identified in PXE patients.
• Missense mutations in GGCX, in conjunction with ABCC6 mutations, were found in patients with PXE-like features and coagulation issues.
• GGCX's role in carboxylating Matrix Gla Protein (MGP), a mineralization inhibitor, was highlighted.

Conclusions:

• Loss-of-function mutations in ABCC6 likely lead to reduced vitamin K-dependent MGP carboxylation, causing pathological connective tissue mineralization in PXE.
• The GGCX gene and MGP carboxylation pathway represent a significant factor in PXE pathogenesis.
• Further research into PXE mechanisms may unveil novel therapeutic interventions targeting the genome-environment interface.