RAPADILINO syndrome
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Summary
RAPADILINO syndrome is an autosomal recessive disorder characterized by radial and patellar aplasia or hypoplasia. Additional findings include small stature, absence of thumbs, dislocation of joints, unusual facies (long face with narrow palpebral fissures, long slender nose, small chin, and unusual ears), cleft or highly arched palate, diarrhoea/vomiting/feeding problems in infancy, and normal intelligence. The acronym RAPADILINO syndrome stands for the hallmark features: RA for radial, PA for both absent/hypoplastic patellas and cleft/high arched palate, DI for diarrhea/dislocated joints, LI for little size/limb malformations, NO for long, slender nose/normal intelligence. RAPADILINO syndrome was first described in families originating from different parts of Finland (14 individuals from from 11 Finnish families), but non-Finnish RAPADILINO patients were later identified. The following features point to an autosomal recessive pattern of inheritance: the parents were healthy in all the families, there have been reports of affected sibs, the sex ratio is equal, and consanguinity was reported in two of the families. RAPADILINO syndrome is caused by mutations in the RECQL4 gene. The function of RECQL4 remains unknown, but domain homology suggests it possesses ATP-dependent DNA helicase activity. RECQL4 is a member of the RECQL gene family: mutations in genes from this group cause Rothmund-Thomson syndrome (RTS) (RECQL4 mutations), Bloom syndrome (RECQL3 mutations), and Werner syndrome (RECQL2 mutations). These syndromes show a remarkable overlap, especially RTS. The high predisposition to malignancies is the most differentiating feature: RAPADILINO syndrome is not characterized by a significant cancer risk. It is hypothesized that the defective helicase activity in the Werner, Bloom and RTS patients makes them prone to cancer and sarcomas, whereas in the RAPADILINO patients, with prevailing helicase activity, the cancer risk is lower. The other distinct clinical difference between RAPADILINO and RTS patients is the occurrence of poikiloderma, which is the hallmark symptom of RTS, but not present in the RAPADILINO patients. In contrast with RTS, RAPADILINO syndrome seems to be more common in females. *Author: Orphanet (January 2005)*.
References
Clinical signs
- Autosomal recessive inheritance
- Clinodactyly of fifth finger
- Helix absent/abnormal
- High vaulted/narrow palate
- Hypoplastic thumb
- Imperforate anus/anal stenosis
- Long/large/bulbous nose
- Malabsorption/chronic diarrhoea
- Micrognatia/retrognatia
- Narrow nasal bridge
- Radius absent/abnormal
- Short stature/dwarfism
Update : 15/04/2007
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