Summary

RAPADILINO syndrome is a syndrome for which the acronym indicates the principal signs: RA for radial ray defect, PA for both patellae hypoplasia or aplasia and cleft or highly arched palate, DI for diarrhea and dislocated joints, LI for little size and limb malformations, NO for long, slender nose and normal intelligence. Prevalence is unknown, but the disease is rare. It was first described in families originating from different parts of Finland, but non-Finnish cases were later identified. Growth delay is both pre- and postnatal. It is aggravated by feeding problems and diarrhea of no known cause. RAPADILINO syndrome is transmitted in an autosomal recessive manner and is caused by mutations of the RECQL4 gene, a member of the family of RecQ-helicase genes which are at the origin of diseases predisposing to cancer. Differential diagnoses include Rothmund-Thomson syndrome (RTS) and Baller-Gerold syndrome (see these terms), which show considerable overlap with RAPADILINO syndrome. Mutations of the RECQL4 gene have also been described for these syndromes. The presence of poikiloderma, a major symptom of RTS, distinguishes this syndrome from RAPADILINO. Radial hypoplasia or aplasia, which is constant in RAPADILINO syndrome, is occasional in RTS. Equally, the presence of craniosynostosis in Baller-Gerold syndrome differentiates it from RAPADILINO syndrome. The three syndromes predispose the risk of developing malign pathologies, although this is significantly greater for RTS (mainly osteosarcoma and cutaneous cancers). The clinical differences can be explained by phenotype-genotype correlation, in particular by preservation of helicases in RAPADLINO syndrome. Orthopedic and nutritional management is recommended when needed and appropriate investigation is recommended in the event of signs suggestive of osteosarcoma.

Expert reviewer(s)

• Pr Laurence FAIVRE-OLIVIER