Hair Shaft Examination in a Child With Global Developmental Delay

A 6-month-old male infant born to nonconsanguineous parents presented with delayed attainment of milestones and lightly colored hairs. Examination revealed a developmental quotient of 50%, microcephaly (35 cm, <-3 Z score), and hypopigmented skin and hair (Figure, A). His elder male sibling also had hypopigmented hairs. Hair microscopy showed large, irregular clumps of melanin (Figure, B). Next-generation sequencing revealed a pathogenic homozygous nonsense variation in the RAB27A gene (c.550C>T, exon 6), confirming the diagnosis of Griscelli syndrome (GS).