Two new hereditary corneal disorders discovered

Two new disorders affecting the cornea have been discovered by researchers at Linköping University. The hereditary disorders were discovered in two Swedish families.

The story begins with a mother and daughter arriving at the eye clinic at the University Hospital in Linköping. They both suffer from recurrent wounds on the cornea, causing pain, watery eyes, sensitivity to light and decreased vision. At the clinic they are seen by Professor Per Fagerholm and Specialist Consultant Björn Hammar.

"They had been referred from a hospital in the county of Småland and their complaint did not match any previously diagnosed disorders. It transpired that many in their extended family suffered from the same problem", says Björn Hammar, who now publishes the research results in his doctoral thesis at LiU.

He created a family tree, going back six generations with 171 individuals born 1854 and later. Of these 44 had suffered from the disorder and nine had undergone corneal grafting. Most had developed symptoms before the age of one. It soon became apparent this was a disorder with autosomal dominant inheritance, meaning you only need to get the abnormal gene from one parent in order for you to inherit the disorder.

Close clinical studies and genetic analyses showed this disorder was clearly demarcated from other disorders with similar symptoms. The disorder was named after the area of Sweden where this family had lived for generations, Dystrophia Smolandiensis.

The research led to data about a similar phenomenon in a different Swedish county, Hälsingland, being revisited and closer examined. This family tree included seven generations and 342 people, of which 84 had symptoms similar to that of the family from Småland, but the overall picture of the disorder deviated enough for a separate diagnosis. The onset in Dystrophia Helsinglandica was usually later, at the ages of 4-7, and the symptoms were worse but less frequent.

"Clinically we can determine that this is two similar but separate disorders. The next stage is to find the mutations in these families and then continue our research with ten further families we know of. This is likely to just be the tip of the iceberg" says Björn Hammar.