[Alder anomaly accompanied by myeloperoxidase mutation]

A third form of the Alder anomaly is described in which the peroxidase of neutrophilic polymorphonuclear cells (PNC) is resistant to fixation in methanol, a necessary step in the May-Grunwald Giemsa staining procedure. This property of the abnormal cells is similar to that of eosinophils, rather than normal PNC. However, the PNC in this form of the condition also have the abnormal granulation typical of the other forms of the anomaly. It is suggested that in this third form, 2 genetic aberrations are involved, 1 affecting the formation of the PNC granules and the other a gene mutation which encodes for the production of myeloperoxidase in those cells.