Brief report:: Inherited and somatic CD3ζ mutations in a patient with T-cell deficiency

A four-month-old boy with primary immunodeficiency was found to have a homozygous germ-line mutation of the gene encoding the CD3 zeta subunit of the T-cell receptor - CD3 complex. CD3 zeta is necessary for the development and function of T cells. Some of the patient's T cells had low levels of the T-cell receptor - CD3 complex and carried the Q70X mutation in both alleles of CD3 zeta, whereas other T cells had normal levels of the complex and bore the Q70X mutation on only one allele of CD3 zeta, plus one of three heterozygous somatic mutations of CD3 zeta on the other allele, allowing expression of poorly functional T-cell receptor - CD3 complexes.