[1] Natl & Kapodistrian Univ Athens, Univ Gen Hosp ATTIKON, Sch Hlth Sci, Dept Pediat 3, Rimini 1, Athens 12462, Greece
[2] Natl & Kapodistrian Univ Athens, Sch Med, Ctr Clin Epidemiol & Outcomes Res CLEO, Chatzigianni Mexi 5, Athens 11528, Greece
[3] Kingston Hosp NHS Fdn Trust, Dept Paediat, Kingston, England
[4] Univ Complutense, Inst Invest Hosp Octubre Imas12 12, Hosp Univ Octubre 12, Pediat Infect Dis Unit,RITIP, Madrid, Spain
[5] Univ Paris 05, EA 73 28, Sorbonne Paris Cite, Hop Necker EM,AP HP,Matern,Unite Med Faetale, F-75015 Paris, France
[6] Fdn IRCCS Policlin San Matteo, Lab Genet Trapiantol & Malattie Cardiovasc, I-27100 Pavia, Italy