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Eur J Hum Genet. 2015 Mar;23(3):409-12. doi: 10.1038/ejhg.2014.118. Epub 2014 Jun 18.

Germline PTPN11 and somatic PIK3CA variant in a boy with megalencephaly-capillary malformation syndrome (MCAP)--pure coincidence?

Author information

1
Institute of Clinical Genetics, Klinikum Stuttgart, Stuttgart, Germany.
2
CeGaT GmbH, Tübingen, Germany.
3
University Hospital, Institute of Human Genetics, University of Magdeburg, Magdeburg, Germany.
4
1] Institute of Clinical Genetics, Klinikum Stuttgart, Stuttgart, Germany [2] CeGaT GmbH, Tübingen, Germany.

Abstract

Megalencephaly-capillary malformation (MCAP) syndrome is an overgrowth syndrome that is diagnosed by clinical criteria. Recently, somatic and germline variants in genes that are involved in the PI3K-AKT pathway (AKT3, PIK3R2 and PIK3CA) have been described to be associated with MCAP and/or other related megalencephaly syndromes. We performed trio-exome sequencing in a 6-year-old boy and his healthy parents. Clinical features were macrocephaly, cutis marmorata, angiomata, asymmetric overgrowth, developmental delay, discrete midline facial nevus flammeus, toe syndactyly and postaxial polydactyly--thus, clearly an MCAP phenotype. Exome sequencing revealed a pathogenic de novo germline variant in the PTPN11 gene (c.1529A>G; p.(Gln510Arg)), which has so far been associated with Noonan, as well as LEOPARD syndrome. Whole-exome sequencing (>100 × coverage) did not reveal any alteration in the known megalencephaly genes. However, ultra-deep sequencing results from saliva (>1000 × coverage) revealed a 22% mosaic variant in PIK3CA (c.2740G>A; p.(Gly914Arg)). To our knowledge, this report is the first description of a PTPN11 germline variant in an MCAP patient. Data from experimental studies show a complex interaction of SHP2 (gene product of PTPN11) and the PI3K-AKT pathway. We hypothesize that certain PTPN11 germline variants might drive toward additional second-hit alterations.

PMID:
24939587
PMCID:
PMC4326712
DOI:
10.1038/ejhg.2014.118
[Indexed for MEDLINE]
Free PMC Article

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