**Acknowledgements**

I would like to express my sincere thanks to Prof. Ilhan Tezcan, MD, PhD and Prof. Deniz Cagdas Ayvaz, MD, PhD for their valuable supports. This study was supported by the grants with the number TSA-2018-17339 and 315S125 from Hacettepe University and TUBITAK, respectively. The authors would like to thank participants for being a part of this study.

*Flow Cytometric Approach in the Diagnosis of Primary Immunodeficiencies DOI: http://dx.doi.org/10.5772/intechopen.96004*
