Swiss researchers have identified the defect in the coding region of the gene responsible for childhood cataract by assessing family members who suffered from autosomal dominant juvenile cataract, according to a study published in the March 2008 issue of the American Journal of Human Genetics.

According to the research team, headed by Barbara Kloeckener-Gruissem of the Institute of Medical Genetics, University Zurich, Switzerland, SLC16A12, a mutation in the carboxylic acid transporter family gene SLC16, could provide a connection between juvenile cataract with microcornea and renal glucosuria.

The researchers identified the nonsense mutation by studying members of a large family with autosomal dominant juvenile cataract, microcornea, and renal glucosuria, and found tissue-specific variability of SLC16A12 transcript levels in control samples, with high expression in the eye and kidney.

SLC16A12 is important for lens and kidney homeostasis, and may lead to renal glucosuria, a non-pathological kidney defect defined by elevated glucose level in the urine without hyperglycemia and without evidence of morphological renal anomalies. Poor homeostasis within the lens leads to alterations of the lens structure, resulting in opacity and leading to cataract.

The researchers concluded that SLC16A12 interferes with homeostasis in the lens, and is biologically relevant as a cause of juvenile cataract. Age-related cataract patients are also being screened for mutations in this gene. The investigators believe that understanding the exact function of SLC16 may open new avenues for non-surgical treatment of cataract.