TGFBR1*6A may contribute to hereditary colorectal cancer.
OBJECTIVE
TGFBR16A is a tumor susceptibility gene that increases breast, colon, and ovarian cancer risk. Fourteen percent of the general population carries TGFBR16A, and TGFBR16A homozygotes have a greater than 100% increased colon cancer risk compared with noncarriers. Low-penetrance genes such as TGFBR16A may account for a sizable proportion of familial colorectal cancer occurrences. To test this hypothesis, we determined whether TGFBR16A contributes to a proportion of mismatch repair (MMR) gene mutation-negative hereditary nonpolyposis colorectal cancer (HNPCC) patients.


METHODS
A case-case study was performed of 208 index patients with HNPCC meeting the Amsterdam criteria. Patients were examined for mutations and genomic rearrangements in the MLH1, MSH2, and MSH6 genes and genotyped for TGFBR16A. Tumor microsatellite instability status was available for 95 patients.


RESULTS
A total of 144 patients (69.2%) carried a deleterious mutation and were classified as positive for MMR gene mutation; 64 patients (30.8%) had no evidence of mutations and were classified as MMR negative. TGFBR16A allelic frequency was significantly higher among MMR-negative patients (0.195) than among MMR-positive patients (0.104; P = .011). The proportion of TGFBR16A homozygotes was nine-fold higher among MMR-negative (6.3%) than among MMR-positive patients (0.7%; P = .032). The highest TGFBR16A allelic frequency was found among MMR-negative patients with tumors exhibiting no microsatellite instability (0.211), and the lowest frequency was found among MMR-positive patients with tumors exhibiting microsatellite instability (0.121); the difference was not statistically significant (P = .17).


CONCLUSIONS
TGFBR16A may be causally responsible for a proportion of HNPCC occurrences.
Bian
Yansong
Y
Cancer Genetics Program, Division of Hematology/Oncology, Department of Medicine, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, 676 N St Clair St, Suite 880, Chicago, IL 60611, USA.
Caldes
Trinidad
T
Wijnen
Juul
J
Franken
Patrick
P
Vasen
Hans
H
Kaklamani
Virginia
V
Nafa
Khédoudja
K
Peterlongo
Paolo
P
Ellis
Nathan
N
Baron
John A
JA
Burn
John
J
Moeslein
Gabriela
G
Morrison
Patrick J
PJ
Chen
Yu
Y
Ahsan
Habibul
H
Watson
Patrice
P
Lynch
Henry T
HT
de la Chapelle
Albert
A
Fodde
Riccardo
R
Pasche
Boris
B
D030201:Activin Receptors, Type I / Q000235:genetics*; D000328:Adult; D020137:Base Pair Mismatch; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000235:genetics*; D004252:DNA Mutational Analysis; D004260:DNA Repair; D005260:Female; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics*
D018125:Receptors, Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human