Tests offer hope in face of deadly genetic condition

Deanne and Alastair Corps in 2001.

Deanne Corps has lost her son and her mother to a rare disease that may also have taken her brother.

And she now knows that she, too, is at risk from the genetically inherited immune system disorder that has afflicted three generations of her family.

The reach of the disorder through Mrs Corps' family came to light only after the death of her 18-year-old son, Alastair.

He had survived lymphoma, a form of cancer, in childhood, but succumbed to glandular fever at Waikato Hospital in January last year. Acute liver failure was the direct cause of his death, but questions remained.

"Here was this apparently healthy young man who had passed away for causes that they couldn't determine," said Mrs Corps, of Wanganui.

Tests later showed he had the rare immune disorder X-linked lymphoproliferative disease (XLP).

Tests of stored samples then revealed that Mrs Corps' mother, who died of lymphoma in 1991, had the disease, and a check of clinical records showed her brother, who died aged 10 of the same cancer in 1977, probably had the immune disorder too.

XLP is passed on to children by the mother, but until Mrs Corps' mother was found to have died of it, it was thought that only boys developed symptoms.

Now Mrs Corps has to have her immune system monitored carefully for lymphoma.

The Auckland District Health Board laboratory, LabPlus, has developed tests for XLP and two other primary immune deficiency disorders - conditions arising from intrinsic or genetic factors rather than external causes - and is the only New Zealand facility where they are available.

A LabPlus doctor, Associate Professor Rohan Ameratunga, said XLP was so rare it probably affected no more than several families in New Zealand. It could lead to lymphoma, common variable immune deficiency or death from glandular fever.

"[The person's] immune system has a hole. The hole is the glandular fever virus. They can respond to other infections, but not this virus. When they get the virus their immune system falls to bits."

Most people caught the virus by the time they were teenagers. Boys with XLP were usually normal until they caught the virus; once they did, almost all died very quickly.

But if the disorder was identified in boys, they could be cured with a bone marrow transplant, Professor Ameratunga said.

LabPlus hopes to develop tests for more of the disorders and, with help from the Immune Deficiencies Foundation, is studying common variable immune deficiency.

"This programme will catapult us to the forefront of primary immune deficiency research," said Professor Ameratunga.

Foundation health co-ordinator Sarah Perry said the aim was to diagnose the disorders early, to prevent deaths and complications such as lung disease. LabPlus providing its tests made that more likely.

She said tests for some primary immune deficiency disorders were available in New Zealand in addition to the new LabPlus tests, but when tests were unavailable in the country, some patients faced having to pay to send samples overseas or to go themselves, as health boards had only limited funds for this work.


THE DISORDERS

* More than 140 types of primary immune deficiency disorders are known.

* Part of the immune system is missing or does not work properly because of intrinsic or genetic factors.

* Some of the disorders are common, some rare.

* Some are life-threatening, but with the commonest type most people don't have symptoms.

* The Auckland District Health Board laboratory has developed tests for three of the disorders and is planning more.

* It can potentially offer fetal testing and wants to prove the tests for use with in-vitro fertilisation so parents can avoid passing on some of the disorders.