Photo by Rod Waddington
Child in Uganda
SAN DIEGO—An inexpensive, rapid, and easy-to-use blood test accurately detected sickle cell disease in young children in Uganda, according to a speaker at the 2018 ASH Annual Meeting.
The test, called HemoTypeSC, uses monoclonal antibodies to detect hemoglobins A, S, and C in a drop of whole blood.
HemoTypeSC costs less than $2 to the end user and delivers results in about 10 minutes.
“This is ideal for use in resource-constrained regions of high prevalence, such as Africa and central India,” said Erik Serrao, PhD, of Silver Lake Research in Azusa, California.
“Early screening plus treatment plus counseling equals saving millions of lives over the coming decades, and we believe HemoTypeSC can form an integral part of the initial part of this equation.”
Dr. Serrao reported results from a study of HemoTypeSC during the late-breaking abstracts session at ASH (abstract LBA-3).
He and his colleagues compared results with the HemoTypeSC test to results with hemoglobin electrophoresis for detection of the phenotypes HbAA (normal), HbAS (sickle cell trait), and HbSS (sickle cell disease).
The investigators compared these two testing methods in 1,000 children between the ages of 1 month and 5 years who were prospectively recruited from hospital wards and outpatient clinics in Uganda.
Results
The initial analysis suggested HemoTypeSC had an overall accuracy of 99.8%, correctly identifying 998 of 1,000 phenotypes as initially determined by electrophoresis.
HemoTypeSC correctly identified 100% of the 720 HbAA specimens and 100% of 182 HbAS specimens.
HemoTypeSC identified as HbSS 98% (96/98) of specimens that were identified as HbSS by electrophoresis. This left two discordant samples, both of which HemoTypeSC identified as HbAS.
Investigators subsequently discovered that both individuals with the discordant samples had previously been diagnosed with sickle cell disease and had received recent transfusions with HbAA blood.
“Therefore, the true phenotype at the time of testing for these samples was HbAS, as hemoglobin A and S were both in the blood,” Dr. Serrao said.
This brought the accuracy rate of HemoTypeSC up to 100%.
Dr. Serrao noted that this study excluded newborns. However, a different study of HemoTypeSC, recently published in the American Journal of Hematology, demonstrated 100% accuracy across multiple phenotypes in the setting of newborn screening.
Implications
Of all the late-breaking abstracts at ASH this year, the study by Dr. Serrao and his colleagues is the one with the potential to save the most lives, according to Mark Crowther, MD, of McMaster University in Hamilton, Ontario, Canada.
He said using current gold-standard methods for diagnosing sickle cell disease is, at minimum, challenging and “frankly impossible” in many low-resource settings because of the cost and the requirement for sophisticated equipment and reliable electricity.
However, he believes HemoTypeSC could change that.
“The ability to diagnose sickle cell disease early and intervene early will result in potentially thousands of infants, who would otherwise die in infancy or early childhood, surviving into adulthood,” Dr. Crowther said.
Dr. Serrao noted that sickle cell disease screening programs have been projected to be cost-effective in Africa. Such programs could even save money for governments over time as budgets are reallocated toward screening, with less money needed for treatment of patients presenting with severe complications in hospitals.
Dr. Serrao reported that he is an employee of Silver Lake Research, which funded this study, approved the study design, and donated HemoTypeSC tests.