Rare Metabolic Gene Unexpectedly Tied to Inherited Blindness

Scientists at the Greenwood Genetic Center (GGC) have led an investigation that identified an unforeseen link between genetic blindness and a gene associated with a rare metabolic disorder.

The research, published in The American Journal of Human Genetics, involved 14 people from 12 families who were diagnosed with retinitis pigmentosa (RP), a hereditary vision impairment that leads to gradual vision deterioration. Genetic analysis showed that all participants had alterations in both versions of the IDUA gene, which is often associated with a rare metabolic disease known as mucopolysaccharidosis type I (MPS I).

However, a number of the individuals involved did not present the wider health issues typically linked to MPS I, like significant physical impairments, heart problems, and skeletal abnormalities, even in their later years.

Genetic conditions do not always follow the patterns we expect. Our findings show that changes in the same gene can sometimes affect the retina while leaving other parts of the body largely unaffected. This phenomenon may represent a significant cause of blindness in patients who remain undiagnosed.

Gavin Arno, PhD, Study Corresponding Author and Associate Director of Research, Greenwood Genetic Center

Researchers at GGC used a one-of-a-kind functional platform to explore how alterations in the IDUA gene affect the body's ability to produce an essential enzyme. Their findings revealed that certain genetic alterations permit a minimal level of enzyme activity to persist; this might clarify why these individuals experience retinal disorders despite lacking the more extensive complications associated with MPS I.

This is an excellent example of why genetic diagnosis cannot always stop with identifying a variant in a gene. By combining genetic analysis with laboratory studies, like enzyme levels, we can better understand why a condition may look very different from one person to another.

Richard Steet, PhD, Study Author and Director of Research, Greenwood Genetic Center

These results expand the spectrum of conditions linked to IDUA and offer new considerations for genetic screening. Scientists recommend that IDUA be evaluated in patients with inherited retinal disease, even in the absence of classic MPS I symptoms.

The research underscores the significance of comprehending how genetic differences influence the body, rather than merely pinpointing the differences themselves. This knowledge could eventually assist scientists and healthcare professionals in identifying patients sooner and gaining insights into possible treatment options.

This global research involved scientists from over 20 institutions, including the Greenwood Genetic Center, the University of Manchester, and other prominent institutions specializing in inherited retinal diseases and metabolic disorders.