Cancer incidence among persons with fragile X syndrome in Finland: a population-based study.
BACKGROUND
Fragile X syndrome is a common inheritable cause of intellectual disability (ID) and is characterised by a large number of CGG repeats at the gene FMR1 located on the X-chromosome. It has been reported that this genetic mechanism may protect against malignant transformations.


METHODS
We extracted from the Finnish registry on persons with ID a cohort of 302 persons with a fragile X diagnosis during 1982-1986. Follow-up for cancer incidence was performed in the Finnish Cancer Registry until the end of the year 2005.


RESULTS
There were 11 reported cancers during the mean follow-up of 21.4 years per person. The expected number of cancers based on the average Finnish population was 13.8 and no statistically significant protective effect was detected [standardised incidence ratios (SIR) 0.80, confidence interval (CI) 95% 0.40-1.4]. An increased risk for lip cancer was found (SIR 23, CI 95% 2.8-85).


CONCLUSIONS
Confirmation of hypotheses about the mechanisms linking FXS and cancer needs further research.
Sund
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R
National Research and Development Centre for Welfare and Health (STAKES), Helsinki, Finland. reijo.sund@stakes.fi
Pukkala
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E
Patja
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K
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D005600:Fragile X Syndrome / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology*; D012720:Severity of Illness Index; D017678:Sex Distribution; D055815:Young Adult