Related Experiment Videos
Strategy linking several analytical methods of neonatal screening for sickle cell disease
R Ducrocq1, O Pascaud, A Bévier
1Laboratoire de Biochimie Génétique, Hôpital Robert Debré, 48 Boulevard Sérurier, 75935 Paris, France. rolande.ducrocq@rdb.hop-ap-paris.fr
Insights
French neonatal screening for sickle cell disease (SCD) identified 1 in 462 infants with SCD. A combined strategy using isoelectric focusing and HPLC reduced diagnostic errors, sparing families unnecessary worry.
Area of Science:
- Medical Diagnostics
- Genetics
- Public Health
Background:
- The French national sickle cell disease (SCD) screening program began in 1995, targeting at-risk newborns.
- Over five years, 115,480 infants were screened, identifying 250 with SCD (1 in 462) and a 5.34% carrier rate.
- Uncommon hemoglobin variants posed diagnostic challenges, accounting for 4% of SS-like profiles.
Purpose of the Study:
- To develop an effective screening strategy for neonatal sickle cell disease.
- To minimize false positive and false negative results in newborn screening.
Main Methods:
- Primary screening utilized rapid and inexpensive isoelectric focusing (IEF).
- Secondary screening employed automated, quantitative cation exchange high-performance liquid chromatography (CE-HPLC).
- Confirmatory methods included a second CE-HPLC, reverse phase-HPLC, and DNA testing for complex cases.
Main Results:
- IEF identified normal profiles in 89% of samples.
- CE-HPLC accurately identified common hemoglobin variants and detected low levels (0.5%) of variants, preventing false negatives.
- A combination of methods confirmed the status of 99.7% of screened infants.
Conclusions:
- The multi-method strategy significantly reduced diagnostic errors, minimizing unnecessary recalls for families.
- The screening approach effectively identified sickle cell disease and carriers in newborns.
- Hereditary fetal hemoglobin (HPFH) remains an unavoidable cause of false positives.
Background:
The French national programme for the neonatal screening of sickle cell disease (SCD) was set up in 1995. This screening is targeted at newborn infants at risk. Over 5 years, 115,480 newborn infants were tested from 80 maternity departments from the northern part of the Paris area. 250 Patients with SCD were identified--that is, one in 462 newborn infants tested. Carriers for a haemoglobin (Hb) variant are frequent (5.34%). Some uncommon Hb variants were also identified, which gave rise to pitfalls to the testing when associated with HbS: HbKorle-Bu, HbHope, HbBougardirey-Mali, and HbLadésirade (4% of SS-like profiles).
Objective:
An effective screening strategy was developed to avoid these false positive and false negative responses.
Methods:
Isoelectric focusing (IEF), the method of primary screening, is rapid and inexpensive. Cation exchange high performance liquid chromatography (CE-HPLC), which is automated, fast, and quantitative was selected as a secondary method.
Results:
IEF diagnosed normal profiles in 89% of the tested samples from newborn infants. CE-HPLC identified most of the common Hb variants by their retention time and the measure of HbA/HbS ratio, important for the differential diagnosis between an asymptomatic HbS carrier and an HbS/beta+thal compound heterozygote. Furthermore, the high sensitivity of the CE-HPLC detected as little as 0.5% of a Hb variant. This avoided false negatives in samples from premature or transfused newborn infants. All samples with SS-like profiles were confirmed with a second CE-HPLC with another programme. A combination of these three methods confirmed the status of 99.7% of the samples from the tested newborn infants. Some cases required a reverse phase-HPLC method (for gamma-globin or alpha-globin chain variants). Finally, some exceptional samples required confirmation by testing DNA extracted with Güthrie paper for a precise diagnosis.
Conclusions:
This effective strategy combining several methods dramatically reduces the risk of errors. Many families are thus spared unnecessary worrying recalls. The only unavoidable cause of false positives remains the HbS/hereditary fetal Hb (HPFH).