Increased colorectal cancer incidence in obligate carriers of heterozygous mutations in MUTYH.
OBJECTIVE
MUTYH-associated polyposis (MAP) is an autosomal recessive disorder caused by mutations in the MUTYH gene. Patients with MAP are at extremely high risk of colorectal cancer, but the risks of colorectal and other cancers in heterozygous carriers of a single MUTYH mutation are uncertain. We performed a retrospective study of cancer incidence and causes of death among obligate MUTYH heterozygote individuals.


METHODS
MAP index cases were identified from polyposis registers in Germany, The Netherlands, and the United Kingdom. Cancer incidence, cancer mortality, and all-cause mortality data were collected from 347 parents of unrelated MAP index cases and the spouses of 3 index cases who were also found to be heterozygous for single MUTYH mutations. These data were compared with appropriate national sex-, age-, and period-specific population data to obtain standardized mortality ratios (SMR) and standardized incidence ratios (SIR).


RESULTS
There was a 2-fold increase in the incidence of colorectal cancer among parents of MAP cases, compared with the general population (SIR, 2.12; 95% confidence interval [CI]: 1.30-3.28). Their colorectal cancer mortality was not increased significantly (SMR, 1.02; 95% CI: 0.41-2.10) nor was overall cancer risk (SIR, 0.92; 95% CI: 0.70-1.18), cancer mortality (SMR, 1.12; 95% CI: 0.83-1.48), or overall mortality (SMR, 0.94; 95% CI: 0.80-1.08).


CONCLUSIONS
The risk of colorectal cancer in heterozygous carriers of single MUTYH mutations who are relatives of patients with MAP is comparable with that of first-degree relatives of patients with sporadic colorectal cancer. Screening measures should be based on this modest increase in risk.
Jones
Natalie
N
Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom.
Vogt
Stefanie
S
Nielsen
Maartje
M
Christian
Daria
D
Wark
Petra A
PA
Eccles
Diana
D
Edwards
Emma
E
Evans
D Gareth
DG
Maher
Eamonn R
ER
Vasen
Hans F
HF
Hes
Frederik J
FJ
Aretz
Stefan
S
Sampson
Julian R
JR
D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000235:genetics* / Q000473:pathology; D016001:Confidence Intervals; D045647:DNA Glycosylases / Q000235:genetics*; D004252:DNA Mutational Analysis; D004502:Education, Medical, Continuing; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D005820:Genetic Testing; D006579:Heterozygote; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D016017:Odds Ratio; D010375:Pedigree; D011336:Probability; D011379:Prognosis; D012042:Registries; D018570:Risk Assessment; D017678:Sex Distribution; D015996:Survival Rate
D045647:DNA Glycosylases; C061738:mutY adenine glycosylase