Fig. 1.

(a) Family pedigree with filled circle representing our affected patient. Squares represent males and circles represent females. (b) Sequencing of patient genomic DNA confirming CYBB mutation (c.935T>G, p.M312R). (c) Determining the patient’s X chromosome inactivation using HUMARA assay. One X allele is active and completely digested by the methylation-sensitive restriction enzyme HpaII (bottom allele), while the second allele is inactive, due to methylated chromosome that resists digestion (top band). The assay confirms a fully skewed X chromosome inactivation pattern in the patient (0:100) when compared to a healthy control (42:58).