Here we report on a child with Li-Fraumeni syndrome with a de novo TP53 mutation c.818G>A, who developed three malignancies at the age of 4 months, 4 and 5 years, respectively. We show that (i) in the choroid plexus carcinoma, the germline mutation was detected in a homozygous state due to copy-neutral LOH/uniparental disomy, (ii) in the secondary AML, a complex karyotype led to loss of the wild-type TP53 allele, (iii) in the Wilms tumor, the somatic mutation c.814G>A led to compound heterozygosity. The findings show that the complete inactivation of TP53 by different mechanisms is an important step towards tumorigenesis.
Keywords: Li-Fraumeni syndrome; TP53; choroid plexus carcinoma; leukemia; sarcoma; uniparental disomy (UPD).
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