X linked agammaglobulinemia: a single centre experience from India

Clinical and Genetic Profile of X-Linked Agammaglobulinemia: A Multicenter Experience From India

Background

There is paucity of literature on XLA from developing countries. Herein we report the clinical and molecular profile and outcome in a multicenter cohort of patients with XLA from India.

Methods

Data on XLA from all regional centers supported by the Foundation for Primary Immunodeficiency Diseases (FPID), USA and other institutions providing care to patients with PIDs were collated. Diagnosis of XLA was based on European Society for Immunodeficiencies (ESID) criteria.

Results

We received clinical details of 195 patients with a provisional diagnosis of XLA from 12 centers. At final analysis, 145 patients were included (137 'definite XLA' and eight 'probable/possible XLA'). Median age at onset of symptoms was 12.0 (6.0, 36.0) months and median age at diagnosis was 60.0 (31.5, 108) months. Pneumonia was the commonest clinical manifestation (82.6%) followed by otitis media (50%) and diarrhea (42%). Arthritis was seen in 26% patients while 23% patients developed meningitis. Bronchiectasis was seen in 10% and encephalitis (likely viral) in 4.8% patients. Pseudomonas aeruginosa was the commonest bacterial pathogen identified followed by Streptococcus pneumoniae, Staphylococcus aureus and Klebsiella pneumoniae. Molecular analysis revealed 86 variants in 105 unrelated cases. Missense variants in BTK gene were the most common (36%) followed by frameshift (22%) and nonsense variants (21%). Most pathogenic gene variants (53%) were clustered in the distal part of gene encompassing exons 14-19 encoding for the tyrosine kinase domain. Follow-up details were available for 108 patients. Of these, 12% had died till the time of this analysis. The 5-year and 10-year survival was 89.9% and 86.9% respectively. Median duration of follow-up was 61 months and total duration of follow-up was 6083.2 patient-months. All patients received intravenous immunoglobulin (IVIg) replacement therapy. However, in many patients IVIg could not be given at recommended doses or intervals due to difficulties in accessing this therapy because of financial reasons and lack of universal health insurance in India. Hematopoietic stem cell transplant was carried out in four (2.8%) patients.

Conclusion

There was a significant delay in the diagnosis and facilities for molecular diagnosis were not available at many centers. Optimal immunoglobulin replacement is still a challenge.

Guidelines for Screening, Early Diagnosis and Management of Severe Combined Immunodeficiency (SCID) in India

Severe combined immunodeficiency (SCID) is one of the most severe and fatal forms of inherited primary immunodeficiency. Early diagnosis of SCID improves the outcome of life before and after hematopoietic stem cell transplant (HSCT). SCID fulfills the internationally-established criteria for a condition to be screened for at birth. T cell receptor excision circle (TREC) assay is commonly used in western countries as part of newborn blood spot screening (NBS) program as the assay has high sensitivity and specificity to identify SCID infants, allowing early intervention and curative bone marrow (BM) transplantation. In India, the blood spot based screening programs are yet to mature into a full-fledged national program. Moreover, TREC assay, a PCR based test, is not widely available and may cost USD 5-7 per test; thus limiting its applicability for screening newborns in Indian scenario. Most of the SCID patients have lymphopenia at birth and routine evaluation for absolute lymphocyte count (ALC) on cord blood samples can help in pre-symptomatic detection and early intervention for neonates with SCID. Although ALC count lacks the sensitivity and specificity of TREC assay; its lower cost and widespread availability makes it an attractive option for identifying newborns with lymphopenia during the post-partum hospital stay. BCG vaccine and other live attenuated vaccines (e.g., oral polio vaccine) should be withheld in lymphopenic infants until SCID is excluded by clinical and/or immunological work-up. A diagnosis of SCID warrants immediate care to prevent and treat infections and wherever feasible, early stem cell transplantation for disease free survival.

[X-linked agammaglobulinemia: experience in a Portuguese hospital]

INTRODUCTION

X-Linked agammaglobulinemia (XLA) is characterized by an arrest of B cell differentiation, leading to recurrent bacterial infections. Lifelong immunoglobulin replacement therapy (IRT) is indicated to prevent infections and their complications.

MATERIAL AND METHODS

A retrospective study of patients with XLA followed in a level three hospital was performed; data was collected retrospectively by review of clinical files.

RESULTS

XLA was diagnosed in 9 children. One (11%) had a positive family history with a prenatal diagnosis. Infection was the clinical presentation in all the others (89%), at an average age of 13 months; diagnosis was established at a mean age of 3.4 years. Acute otitis media (7/9) and pneumonia (5/9) were the most frequently observed. Seven (78%) presented serum immunoglobulin G (IgG) levels below 200mg/dL and all of them had CD19(+) B cells below 2%. Neutropenia was present at diagnosis in three patients (33%). Bruton tyrosine kinase (BTK) mutations were identified in all cases. Intravenous IRT was initiated, switched later to subcutaneous administration, in all. The mean time of follow-up was 10.7 years with cumulative time of 97 years. Eight children (89%) achieved IgG serum levels above 800 mg/dL. One presented lower values due to renal loss. No deaths occurred. After diagnosis the most frequent infections were acute otitis media (6/9). In spite of stable adequate IgG levels on IRT, two patients developed bronchiectasis.

CONCLUSIONS

XLA overall prognosis is good, as long as patients have an early and adequate treatment. However, bronchiectasis can occur even on adequate immunoglobulin replacement therapy.