Haploinsufficient Bmp4 ocular phenotypes include anterior segment dysgenesis with elevated intraocular pressure

Area of Science:

• Ophthalmology
• Developmental Biology
• Genetics

Background:

• Glaucoma is a leading cause of blindness, often linked to high intraocular pressure (IOP).
• Familial cases of glaucoma involve anterior segment dysgenesis, with causative genes and mechanisms often unknown.
• Bone morphogenetic proteins (BMPs) are crucial developmental signaling molecules.

Purpose of the Study:

• To investigate the role of Bmp4 gene dosage in ocular development.
• To determine if Bmp4 deficiency contributes to developmental glaucoma.

Main Methods:

• Utilized Bmp4+/- mice to study ocular development and glaucoma.
• Analyzed anterior segment structures, intraocular pressure, and posterior segment development.
• Assessed the influence of genetic background on Bmp4+/- phenotypes.

Main Results:

• Bmp4+/- mice exhibited anterior segment abnormalities, including malformed or absent drainage structures (trabecular meshwork, Schlemm's canal).
• Severe drainage defects correlated with elevated IOP.
• Phenotype severity and penetrance varied significantly with genetic background, being most pronounced in C57BL/6J mice.

Conclusions:

• Heterozygous Bmp4 deficiency causes anterior segment dysgenesis and elevated IOP, resembling human developmental glaucoma.
• BMP4 is a strong candidate gene for Axenfeld-Rieger anomaly and other developmental glaucomas.
• BMP4 is critical for optic nerve development, particularly on the C57BL/6J background, and Bmp4+/- mice serve as a model for studying ocular development and genetic modifiers.