Bubble baby syndrome risks for children of cousin marriage

'Bubble baby' Khadija shortly after her bone marrow transplant

A leading doctor who treats children born without an immune system has revealed a disproportionate number of his patients are Asian.

Professor Andrew Cant says that 35% of children he treats are British Asian.

In most cases the parents are first cousins who have married each other.

Severe Combined Immune Deficiency Syndrome is a rare inherited genetic disorder. Around one in 300,000 children is born with the condition, often known as "bubble baby syndrome".

Professor Cant, director of the Children's Bone Marrow Transplant Unit at the Great North Children's Hospital in Newcastle, says that South Asians would normally be expected to account for 5% of patients.

Early testing

Khadija Ibrahim, aged 7, was born with a defective immune system. Her mother Samina suspected there was a problem soon after her daughter was born.

"When she was three to four months old she started catching infections. So every time we went out to the park or anywhere she'd always come back with an infection and she'd have to go onto antibiotics, so we were in and out of hospital every other week," she said.

Subsequent tests revealed Khadija's immune system was not functioning properly.

Professor Cant explains the implications of immune deficiency.

"Severe defects mean that even a simple germ, that in healthy people causes nothing more than a cold, will cause their death within a year of being born," he said.

A bone marrow transplant was Khadija's only chance of survival.

This was carried out at Professor Cant's unit, one of only two centres in the UK and Ireland that treat "bubble babies".

Khadija has since made a full recovery. During a trip to London with her family she talks excitedly about the tourist attractions she hopes to visit.

It is hard to believe this energetic, effervescent young girl was once so sick that a kiss from her mother had the potential to kill her.

Other children are not so fortunate. Mohammed Mahboub knows all too well the pain of losing a young child to this illness.

He and his wife witnessed their five-year-old daughter struggle through the condition after undergoing an unsuccessful bone marrow transplant.

Now fully recovered Khadija is able to go sightseeing without fear of catching infections

"It was a battle for five years, every aspect of this illness…you can't say there was one day where it was easy going, every single day was a battle," he said.

Cousin marriages

Every year between 30 to 40 children undergo bone marrow transplants at Professor Cant's unit, of which 35% of patients are Asian.

Professor Cant says that in almost all cases, the children are the product of first cousin marriages.

"If you marry your cousin, you and your husband or wife will have a copy of the same defective gene that you've inherited from your common relative, usually a grandparent or a great grandparent.

"That means that your children have a one in four risk of picking up two copies of the defective gene and so having a part of their immune system missing," he explained.

Professor Cant hopes that increased awareness will encourage couples in consanguineous marriages to be aware of the risks and seek help earlier if they suspect a problem.

He believes this would opens up the possibility in many cases of ante-natal diagnosis or post-natal diagnosis.

The earlier the diagnosis the higher the chances there are of a child surviving.

"Luckily we've seen Khadija grow and she's done really well. There is always hope," said Samina.

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