Nezelof syndrome (also known as "Thymic dysplasia with normal immunoglobulins") is an autosomal recessive congenital immunodeficiency condition due to underdevelopment of the thymus. An association with CD44 has been proposed.
The defect is a type of purine nucleoside phosphorylase deficiency with inactive phosphorylase. This results in an accumulation of deoxy-GTP which inhibits ribonucleotide reductase. Ribonucleotide reductase catalyzes the formation of deoxyribonucleotides from ribonucleotides. Thus, DNA replication is inhibited and cells cannot replicate.
Nezelof syndrome Wikipedia
The disorder was characterized in 1964. It is considered to be a form of combined immunodeficiency in ICD-10 but a deficiency of cell-mediated immunity in ICD-9.
It causes severe infections and malignancies. it is characterized by elevated immunoglobulins that function poorly.
Treatment includes antimicrobial therapy, IV immunoglobulin, bone marrow transplantation, thymus transplantation and thymus factors.