Figure 3

Imaginary example of a family with hereditary paragangliomas and genomic imprinting. The pedigree has four generations (I-IV). Expression of the disease skips one or two generations. In these generations, the genetic predisposition is present. In the first generation (I) the mother (I 2) is a carrier of the paraganglioma disease gene and has expression of the disease. Her daughter (II 1) inherited the mutated paraganglioma gene, but will not develop paragangliomas. She will transfer the mutated paraganglioma gene to two of her children (daughter III 2 and son III 4). These children will not develop the disease, but pass the predisposition to the next generation. The granddaughter of (II 1) IV 1 has the predisposition but no expression, whereas the grandson IV 3 and granddaughter IV 4 have both the predisposition and expression of the disease. The son (II 4) of I 2 has also inherited the disease gene from his mother, but will not have symptoms. His son (III 5) is a paraganglioma carrier and will have complaints just the same as his sister III 7. His children (IV 6 and 7) have predisposition for paragangliomas and will have the disease. The son and daughter (IV 8 and 9) of III 7 do inherit the mutated paraganglioma gene from their mother, but will not have symptoms.