Phenotypic Prenatal Diagnosis of Chronic Granulomatous Disease: A Useful Tool in The Absence Of Molecular Diagnosis

Abstract

Chronic granulomatous disease (CGD) is an inherited immunodeficiency disorder affecting the microbicidal function of the phagocytes. It is characterized by susceptibility to recurrent infections leading to significant morbidity and mortality. Antibacterial and antifungal prophylaxis, though, has significantly reduced the rate and severity of the infections; the breakthrough infections still remain a challenge. Currently, allogenic haematopoietic stem cell transplantation is the only curative option which is very expensive and unavailable for many due to lack of suitable donor. Thus, prenatal diagnosis (PND) forms an important component of management in the affected families. PND is challenging in families approaching late in pregnancy with an uncharacterized molecular defect. In such cases, PND can be performed by analysis of NADPH activity of fetal blood (FB) neutrophils at 18-20 weeks of gestation. Cord blood samples at 18 weeks of gestation from healthy control were used to establish normal ranges for NBT and DHR. PND was offered for six pregnancies (NBT: n = 3, DHR: n = 6) with index cases of CGD confirmed by abnormal NBT and DHR analysis. NBT and DHR tests were found to be negative for all the six cases, confirming the same on samples post-delivery. NBT and DHR tests offer a rapid and sensitive PND of CGD in the absence of facilities for molecular diagnosis. It was observed that addition of CD15 along with CD45 led to an accurate DHR analysis. It is recommended to perform the diagnosis with adequate precautions only at centres with considerable experience and expertise in the diagnosis of CGD.