Congenital Malalignment of Great Toenails in Two Sets of Monozygotic Twins

To the Editor.—  Malalignment of the great toenails is being increasingly recognized as a cause of infantile and childhood onychogryphosis and ingrown toenail.¹ We report two sets of monozygotic twins with congenital malalignment of the great toenails in each set.

Report of Cases.—  We have observed two sets of monozygotic twins aged 3 and 8 years. Abnormal great toenails were noted at birth in all four children. However, in both sets of twins, only one sibling had bilateral onychogryphosis; the other sibling had one onychogryphotic nail, the other great toenail was only slightly malaligned and was neither thickened nor dystrophic.

Comment.—  Samman described a dystrophy affecting one or both great toenails that was present at birth.² The nails are darker and shorter than normal and tend to be pointed laterally. The nails grow slowly, develop transverse ridges, and may be shed. Baran et al³ have suggested that