Volume 10 Supplement 1
Neutropenia in patients with adenosine deaminase deficiency
© Kim et al; licensee BioMed Central Ltd. 2014
Published: 3 March 2014
Adenosine deaminase (ADA) deficiency is a disorder where the accumulation of purine metabolites, which are particularly toxic to lymphocytes, can lead to severe, life threatening infections. In addition, ADA deficiency also affects other tissues. Few reports describe the presence of neutropenia in these patients, primarily in older patients after hematopoietic stem cell transplantation (HSCT) or gene therapy. We hypothesized that abnormal purine metabolism could also affect granulopoiesis.
The objective of the study was to assess the frequency and nature of neutropenia in patients with ADA deficiency in the first 180 days of life.
This retrospective study analyzed all patients who were diagnosed with ADA deficiency at the Hospital for Sick Children between 1984 and 2012 and had at least one documented complete blood count with differential in the first 180 days of life.
A diagnosis of ADA deficiency was made when erythrocytes ADA enzyme activity was less than 1-2% of control and/or demonstration of mutations in the ADA gene.
Neutropenia was defined as the absolute neutrophil count of less than 6.0 x 109/L for ages ≤ 6 days, less than 1.5 x 109/L for ages 7-13 days, less than 1.0 x 109/L for ages 14-89 days and less than 1.5 x 109/L for ages ≥ 90 days. Patients were excluded if neutropenia was first documented after chemotherapy for HSCT.
Thirteen patients with ADA deficiency were included in the study. Nine of the 13 patients had neutropenia that was first documented within the first 180 days of life (median age of first neutropenia 70 days, range 1-176 days). In 5 patients, the neutropenia was not present on the initial blood count but developed over time. The lowest neutrophil counts ranged from 0.11-1.08 x 109/L (median 0.5 x 109/L). The neutropenia developed in 7 patients prior to the onset of cotrimoxazole or other medications that commonly have myelosuppressive effects. The neutropenia was not associated with infections commonly causing neutropenia or with autoimmune manifestations. Bone marrow examinations in 2 patients with neutropenia were reported as normal. The neutropenia improved spontaneously in 3 patients, while in 4 additional patients it resolved after initiation of PEG-ADA replacement therapy or HSCT.
Neutropenia occurs commonly in patients with ADA deficiency. Further studies are required to determine the pathogenesis of the neutropenia in ADA deficiency.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.