Neonate with Congenital Thrombotic Thrombocytopenic Purpura: a Case Report of a de novo Compound Heterozygote Mutation in ADAMTS13 Gene and Review of Literature.

Background: Congenital thrombotic thrombocytopenic purpura (TTP) is rare and is prone to misdiagnosis or missed diagnosis in clinical. The relationship between genotype and phenotype needs further study.

Methods: A 15-hour-old Chinese girl develops jaundice. Her platelet counts suddenly decreases with bleeding spots on the left side of chest, upper abdomen, and bilateral groin on the fourth day after birth. The plasma ADAMTS13 activity and inhibitor are detected by residual collagen binding assay. ADAMTS 13 gene is detected by next generation sequencing.

Results: The plasma ADAMTS13 activity of the patient is shown to be severely deficient, but without inhibitor. Gene sequencing analysis shows that the patient carries a compound heterozygote mutation of ADAMTS13 gene, one is c.1564T>C, p.(Cys522Arg) on exon 13 of the ADAMTS13 gene, a heterozygote missense mutation. It is identified as a de novo suspected pathological variation. The other is c.330+1G>A on intron 3 of the ADAMTS13 gene, a heterozygote splicing mutation. Her father and elder sister carry c.1564T>C, p.(Cys522Arg) on exon 13 of the ADAMTS13 gene, a heterozygote missense mutations. Her mother carries c.330+1G>A on intron 3 of the ADAMTS13 gene, a heterozygote splicing mutation.

Conclusions: The deficiency of ADAMTS13 caused by one heterozygote missense mutation and the other heterozygote splicing mutation are responsible for the episode of this congenital TTP patient.