Sequencing of TGF-beta pathway genes in familial cases of intracranial aneurysm.
OBJECTIVE
Familial aggregation of intracranial aneurysms (IA) strongly suggests a genetic contribution to pathogenesis. However, genetic risk factors have yet to be defined. For families affected by aortic aneurysms, specific gene variants have been identified, many affecting the receptors to transforming growth factor-beta (TGF-beta). In recent work, we found that aortic and intracranial aneurysms may share a common genetic basis in some families. We hypothesized, therefore, that mutations in TGF-beta receptors might also play a role in IA pathogenesis.


METHODS
To identify genetic variants in TGF-beta and its receptors, TGFB1, TGFBR1, TGFBR2, ACVR1, TGFBR3, and ENG were directly sequenced in 44 unrelated patients with familial IA. Novel variants were confirmed by restriction digestion analyses, and allele frequencies were analyzed in cases versus individuals without known intracranial disease. Similarly, allele frequencies of a subset of known SNPs in each gene were also analyzed for association with IA.


RESULTS
No mutations were found in TGFB1, TGFBR1, TGFBR2, or ACVR1. Novel variants identified in ENG (p.A60E) and TGFBR3 (p.W112R) were not detected in at least 892 reference chromosomes. ENG p.A60E showed significant association with familial IA in case-control studies (P=0.0080). No association with IA could be found for any of the known polymorphisms tested.


CONCLUSIONS
Mutations in TGF-beta receptor genes are not a major cause of IA. However, we identified rare variants in ENG and TGFBR3 that may be important for IA pathogenesis in a subset of families.
Santiago-Sim
Teresa
T
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Mathew-Joseph
Sumy
S
Pannu
Hariyadarshi
H
Milewicz
Dianna M
DM
Seidman
Christine E
CE
Seidman
J G
JG
Kim
Dong H
DH
D030201:Activin Receptors, Type I / Q000235:genetics; D000368:Aged; D000483:Alleles; D015703:Antigens, CD / Q000235:genetics; D004247:DNA / Q000235:genetics; D017931:DNA Primers; D000071063:Endoglin; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011509:Proteoglycans / Q000235:genetics; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D011956:Receptors, Cell Surface / Q000235:genetics; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D020521:Stroke / Q000209:etiology / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics*
D015703:Antigens, CD; D017931:DNA Primers; C064206:ENG protein, human; D000071063:Endoglin; D011509:Proteoglycans; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; C071736:betaglycan; D004247:DNA; D017346:Protein Serine-Threonine Kinases; C425423:ACVR1 protein, human; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; C000625841:TGFBR1 protein, human