Further delineation of Costello syndrome.

We report on a 6-year-old girl with Costello syndrome. Main manifestations included poor postnatal growth, relative macrocephaly, curly hair, distinct "coarse" face, mild mental retardation, happy and sociable personality, loose dark skin particularly of hands and feet, acanthosis nigricans, thin deep set nails, enamel hypoplasia of teeth, and hyperextensible joints. The absence to date of perioral and nasal papillomata in this girl suggests that Costello syndrome is clinically recognizable even before appearance of such papillomata. Manifestations are compared to the four previously reported sporadic cases.