RAPADILINO syndrome

RAPADILINO syndrome is a rare condition that involves many parts of the body. Bone development is especially affected, causing many of the characteristic features of the condition.

Most affected individuals have underdevelopment or absence of the bones in the forearms and the thumbs, which are known as radial ray malformations. The kneecaps (patellae) can also be underdeveloped or absent. Other features include an opening in the roof of the mouth (cleft palate) or a high arched palate; a long, slender nose; and dislocated joints.

Many infants with RAPADILINO syndrome have difficulty feeding and experience diarrhea and vomiting. The combination of impaired bone development and feeding problems leads to slow growth and short stature in affected individuals.

Some individuals with RAPADILINO syndrome have harmless light brown patches of skin that resemble a skin finding known as café-au-lait spots. In addition, people with RAPADILINO syndrome have a slightly increased risk of developing a type of bone cancer known as osteosarcoma or a blood-related cancer called lymphoma. In individuals with RAPADILINO syndrome, osteosarcoma most often develops during childhood or adolescence, and lymphoma typically develops in young adulthood.

The condition name is an acronym for the characteristic features of the disorder: RA for radial ray malformations, PA for patella and palate abnormalities, DI for diarrhea and dislocated joints, LI for limb abnormalities and little size, and NO for slender nose and normal intelligence.

The varied signs and symptoms of RAPADILINO syndrome overlap with features of other disorders, namely Baller-Gerold syndrome and Rothmund-Thomson syndrome. These syndromes are also characterized by radial ray defects, skeletal abnormalities, and slow growth. All of these conditions can be caused by mutations in the same gene. Based on these similarities, researchers are investigating whether Baller-Gerold syndrome, Rothmund-Thomson syndrome, and RAPADILINO syndrome are separate disorders or part of a single syndrome with overlapping signs and symptoms.