Dear , dont worry Try to avoid, There is risk. If u want to take risk u can,,, Its uncertain  if u are lucky won't be hereditary problem but there is very high risk .

Actually it's better to avoid consanguineous marriage. It can lead to genetic abnormalities in the baby and overall inferiority. That is why nature promotes genetic variation. Prevention beforehand is not that much possible because there can be lots of genetic defects to search for but still you should look for common recessive diseases like thalassaemia. Also you can go for artificial insemination or test tube baby or adopt babies if you don't want to take any risk provided you are okay with not being the biological father. Also you should keep in mind that it doesn't also signify that all babies born out of consanguineous marriage will have any abnormality but the probability is higher than that of non-consanguineous marriage.