Genetic screening reveals girl misdiagnosed with life-limiting illness

Genetic screening has revealed a little girl was misdiagnosed with a life-limiting illness and instead has a condition which only affects a handful of children across the UK.

Addison Black, five, from Wallsend, North Tyneside, was first thought to have Joubert syndrome, a brain development disorder, but experts from Newcastle University have given her family hope after diagnosing Poretti-Boltshauser syndrome (PBS), which is rarer and milder.

Her family is one of four across the UK who have had a diagnosis changed from Joubert to PBS, following an expert review of symptoms, brain scans and genetic sequencing.

Poretti-Boltshauser syndrome
Addison Black with her mother Carli (Newcastle University/PA)

PBS is so new that one of the experts it is named after, Professor Eugen Boltshauser, is still working.

A key feature of Poretti-Boltshauser is that it is non-progressive and does not lead to kidney failure and other life-threatening complications associated with other brain diseases such as Joubert syndrome.

The findings are important for the NHS as genome sequencing is becoming mainstream so this rare disorder can be identified quickly if considered alongside other diseases with similar characteristics.

Professor John Sayer, deputy dean of clinical medicine at Newcastle University, said: “Our study shows that by carefully re-evaluating children with a clinical label of Joubert syndrome, we were able to make both a clinical and genetic diagnosis of a much rarer, but milder, syndrome called Poretti-Boltshauser.

Poretti-Boltshauser syndrome
Addison with her brother Coby (Newcastle University/PA)

“Our study revealed that children with congenital brain disorders may have a delayed or incorrect diagnosis due to poor recognition of key features on brain imaging and incomplete genetic testing.”

Addison’s parents Carli and Stewart Black were shocked when her diagnosis changed, and their relief was tinged with worry about the unknown future PBS could bring.

Mrs Black, a former nurse, said: “When your child has complex needs then your whole life understandably revolves around them and making sure they’re OK and have the best treatment possible.

“We knew from a very young age that something was not right with Addison’s development as she wasn’t hitting the milestones – she couldn’t make eye contact, had head twitching and didn’t walk until after the age of three.

Poretti-Boltshauser syndrome
Addison Black (Newcastle University/PA)

“When we were given the initial diagnosis of Joubert syndrome it was heartbreaking as it’s a life-limiting illness and that was always in the back of our minds.

“But to then be told after genetic screening that Addison had a different condition it came as a bolt out of the blue as we didn’t expect it and we had never heard of Poretti-Boltshauser syndrome.

“To be given this diagnosis means that we can speak to the few other families in a similar situation and learn from one another’s experiences, which is so important in our understanding of Addison’s complex needs.”

Addison is regularly monitored by specialists and she enjoys life at school and spending time with her older brother Coby, 10.