Somatic mosaicism of the PIK3CA gene identified in a Hungarian girl with macrodactyly and syndactyly

Kornélia Tripolszki, Rachel Knox, Victoria Parker, Robert Semple, Katalin Farkas, Adrien Sulák, Emese Horváth, Márta Széll, Nikoletta Nagy*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Isolated macrodactyly (OMIM 155500) belongs to a heterogeneous group of overgrowth syndromes. It is a congenital anomaly resulting in enlargement of all tissues localized to the terminal portions of a limb and caused by somatic mutations in the phosphatidylinositol 3-kinase catalytic alpha (PIK3CA, OMIM 171834) gene. Here we report a Hungarian girl with macrodactyly and syndactyly. Genetic screening at hotspots in the PIK3CA gene identified a mosaic mutation (c.1624G > A, p.Glu542Lys) in the affected tissue, but not in the peripheral blood. To date, this somatic mutation has been reported in eight patients affected by different forms of segmental overgrowth syndromes. Detailed analysis of the Hungarian child and previously reported cases suggests high phenotypic diversity associated with the p.Glu542Lys somatic mutation. The identification of the mutation provides a novel therapeutic modality for the affected patients: those who carry somatic mutations in the PIK3CA gene are potential recipients of a novel "repurposing" approach of rapamycin treatment.

Original languageEnglish
Pages (from-to)223-226
Number of pages4
JournalEuropean journal of medical genetics
Issue number4
Publication statusPublished - 1 Apr 2016


  • Macrodactyly and syndactyly
  • Overgrowth syndromes
  • Phenotypic diversity
  • PIK3CA gene
  • Somatic mutation


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