Genetic test speeds up diagnosis for children with cataracts
A blood test for children born with cataracts
will allow faster diagnosis and more personalised treatment,
according to researchers from Manchester
The team, from the Centre for Genomic Medicine a
collaboration between Central Manchester University Hospitals NHS
Foundation Trust and The
University of Manchester, have developed a test that checks all
genes known to cause congenital cataracts using just one blood
"Using next-generation sequencing, we are now able to identify
the cause of cataracts in children in a way that is much faster and
more cost-effective than the current method," said Rachel
Gillespie, who developed the test and spoke at speaking at the
recent British Genetic Medicine conference.
Congenital cataracts are a leading cause of blindness in
children, affecting around 200,000 children around the world every
year. It is thought around half of cases are due to genetic
mutations whilst the remainder are caused by environmental risk
factors during pregnancy, for example exposure to infections such
Mutations in over 100 genes have been linked to congenital
cataracts. Conventional screening methods involve the consecutive
testing of each gene separately to determine the precise genetic
cause, which is a time-consuming and costly process.
"At the moment, screening for one gene takes around four weeks.
There are more than 100 known genes linked to congenital cataracts,
so establishing the cause by screening genes individually can
sometimes take years," said Gillespie. "Our test looks at all of
these genes in parallel, so patients can be diagnosed much faster
and receive the treatment, clinical management and genetic
counselling they need."
As more patients are tested and more knowledge is gained about
the genetic basis of the condition, it is hoped that pinpointing
the exact mutation responsible will enable doctors to make more
accurate predictions regarding how the cataracts may progress and
what the outcome of surgery may be.
Genetic testing can also bring to light more complex conditions
whose symptoms typically do not emerge until later in life. "In
some cases, we have identified that the cataracts aren't just a
standalone problem, but a symptom of a more complex syndrome," said
Gillespie, from the Faculty's Institute of Human Development. "This
includes Warburg micro syndrome and galactokinase deficiency, both
rare conditions that are probably under-diagnosed, as warning signs
in children can be subtle."
The team, from The University of Manchester and the Central
Manchester NHS Foundation Trust, are validating the test and it
will become available on the NHS by December this year, from which
point they will be accepting samples for diagnostic testing. The
team consists of Professor Chris Lloyd from Manchester Royal Eye
Hospital, Professor Graeme Black and Professor Jill Clayton-Smith
St Mary's Hospital and University of Manchester Institute of Human
Development and Rachel Gillespie, University of Manchester.
The research was funded by Fight for Sight.