Absent or defective thumbnails may provide a dermatologic clue to a congenital syndrome involving other cutaneous, musculoskeletal, and perhaps renal anomalies.
The slightest and most common association is the absence of the ulnar half of each thumbnail and of the patellae. Arthrodysplasia of the elbow, particularly congenital luxation of the radius, is somewhat less frequently present. Cases showing numerous other musculoskeletal defects have been classified as Turner's syndrome; the Bonnevie-Ullrich syndrome seems also to be the same, with additional findings including webbing of the neck, laxity of the skin, and anomalies of the cranial nerves.
Of particular interest is the occurrence of "iliac horns" arising from the posterior aspect of the iliac bones. These were present in a kinship described by Hawkins et al., who added renal dysplasia to the syndrome. Four members of the family they reported showed persistent albuminuria with casts of all types and occasional red blood
LEVAN NE. Congenital Defect of ThumbnailsA Dermatologic Manifestation of a Congenital Syndrome Including Musculoskeletal Defects, Absent Patellae, and Renal Dysplasia. Arch Dermatol. 1961;83(6):938–940. doi:10.1001/archderm.1961.01580120050012