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

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Tripolszki, Kornélia 
Knox, Rachel 
Parker, Victoria 
Farkas, Katalin 


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.



Macrodactyly and syndactyly, Overgrowth syndromes, PIK3CA gene, Phenotypic diversity, Somatic mutation, Child, Preschool, Class I Phosphatidylinositol 3-Kinases, Female, Fingers, Humans, Hungary, Limb Deformities, Congenital, Mosaicism, Mutation, Phosphatidylinositol 3-Kinases, Syndactyly

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Eur J Med Genet

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Elsevier BV
This research was supported by the European Union and the State of Hungary, co-financed by the European Social Fund in the framework of TÁMOP-4.2.4.A/ 2-11/1-2012-0001 “National Excellence Program.” Nikoletta Nagy was also supported by the Hungarian Scientific Research Fund (OTKA) PD104782 grant.