Gene genies nail 'curse'

Patricia Lundon-Treweek and son Dylan, 12, have both been afflicted. Picture / Paul Estcourt

Patricia Lundon-Treweek's family have thought for generations that the bad sight and intellectual disabilities suffered by some of their members result from an ancient Maori curse.

She and a relation even sought the advice of tohunga.

Now, scientists have discovered a faulty gene that is causing the moderate to severe visual impairment in up to one-third of the Auckland woman's extended family of about 150.

The gene also partly explains the autism afflicting three of them, all males.

And there is at least the possibility of finding a cure.

"Because it's a calcium-channel defect, there's drugs on the market that deal with that. It may be that something out there could be available to us," Patricia Lundon-Treweek said yesterday.

"I'm probably the worst family affected. I can't hold a driver's licence and I have trouble reading normal print."

Her twin boys, 12-year-old Dylan and Jay, have minimal sight and severe autism that has left them unable to speak or communicate.

However, her "very clever" 3-year-old daughter, Shyla, is unaffected and tries to sneak biscuits under her mother's nose, "but I've got perfect hearing".

The inherited eye disorder has been in the extended family for at least five generations. It affects both sexes but is more severe in males.

A paediatrician and ophthalmologist first started investigating in the 1990s after the high number of vision-loss cases from Patricia Lundon-Treweek's extended family was noticed.

She became involved in the research, contacting family members and compiling a family tree.

An Otago University team led by molecular geneticist Marion Maw identified, from blood samples, a subtle change in the gene that controls the flow of calcium into the light-sensing cells of the eye. Calcium is thought to regulate these cells' signalling to the brain through nerves.

The research will be published this week in the international journal Proceedings of the National Academy of Sciences.

Dr Maw said finding a drug to treat the vision loss was a "theoretical possibility, but we need to explore the practicalities of it".

"We have got new insights into how normal vision works and we hope to get more insights into that and the particular things going wrong in the family.

"Those are the guaranteed yields. Treatment that works, that would be a bonus."

Dr Maw was "pretty sure" the gene mutation was responsible for the three cases of autism, "but the family members are needing another gene or two, or environmental factors, before the autism develops".

Patricia Lundon-Treweek said the findings had given her hope, but she still believed in the curse.

"There's a cultural part of me that will never let that go, but I don't believe that it will last forever."

How it works

* Scientists have found a rare mutation in a gene linked to vision loss and autism in one extended family.

* The gene regulates the flow of calcium to light-sensing cells in the eye. Calcium is thought to play a role in sending nerve signals to the brain.

* Otago University researchers have discovered that a mutation in this gene can mean the channel is always open.

* Eventually, they hope to find a drug treatment to alleviate the vision loss.