Prenatal α-Thalassemia Testing

When a four-deletion panel is negative

A multiplex assay targeting --SEA, --THAI, --CR, and --SA cannot, from its stated scope alone, exclude other α⁰-thalassemia deletions. The separate report of a novel Dongxing deletion makes the residual-risk question concrete: when parental hematology or family history remains suggestive after a negative targeted result, what criteria trigger broader deletion analysis or sequencing? Validation also needs to show whether rare, novel, and nondeletional alleles were represented—or explicitly leave them outside the assay’s claims.