Chronic cough is one of the most common complaints of childhood to consult a doctor. There are many causes such as respiratory tract infections, gastroesophageal reflux, persistent bacterial bronchitis, asthma, cystic fibrosis, congenital malformations, and foreign body aspiration in children under the age of five. However, neither transient hypogammaglobulinemia of infancy (THI) among the causes of chronic cough, nor chronic cough among the application complaints of THI are not questioned. In this study, we aimed to draw attention to the role of THI in the etiology of chronic cough under the age of five. Our study included 55 pediatric patients under the age of five who applied to the pediatric pulmonary diseases outpatient clinic in between January 2015 and December 2020 with the complaint of chronic cough, who were excluded from other causes of chronic cough in etiology, and who met the criteria for THI according to the European Society for Immunodeficiencies (ESID). Demographic, clinical and laboratory characteristics and follow-ups of these patients were reviewed retrospectively. In our study, the mean age of 55 patients at admission was 21.73 ± 11.50 months (median age: 18 months), and the mean age of IgG recovery was 38.65 ± 16.81 months. The mean recovery time was 16.93 ± 12.85 months. Of the patients, 22.4% had a history of consanguinity, 23.4% had prematurity, and 18.2% had a frequent sickness in siblings. The most common complaint accompanying chronic cough in patients was frequent respiratory tract infection, 16.3%. Along with IgG, 26.4% of the patients had low IgA and 31.5% had low IgM in laboratory testing. In antibody responses, isohemagglutinin, anti-tetanus, anti-pneumococcal, anti-HBs vaccine responses were found to be positive in 90.6%, 63.9%, 66.7% and 97.7% of the cases, respectively. 72.7% of the patients received inhaler treatment, 45.5% received antibiotic prophylaxis, and 2.2% received intravenous immunoglobulin (IVIg) treatment. After the IgG value of the patients returned to normal, it was observed that 86.3% of the patients’ cough complaint have disappeared. Transient hypogammaglobulinemia of infancy mostly presents with recurrent lower and upper respiratory tract infections. The most common complaint is cough. It is not questioned whether the cough is chronic or not. In this study, we aimed to investigate the follow-up and prognosis of patients under the age of five who had a chronic cough complaint, when other causes of cough were ruled out and THI was detected. In the study, when the IgG levels of the patients return to normal, the cough complaints disappear to a large extent, showing that THI may also be among the causes of chronic cough.

Background: CD19 molecule found on B lymphocyte surface forms CD19 complex together with CD21, CD81, CD225 in mature B cells and regulates B lymphocyte activation with antigen stimulation. Mutation(s) in the gene encoding the CD19 molecule affect CD19 protein expression and primary immunodeficiency (PID) occurs. Some genetic method, especially sanger and next generation sequencing and flow cytometric methods are widely used in the diagnosis of PID. The RFLP method, which is faster and cheaper than other mutation detection methods, is rarely used in the diagnosis of PID. The study aimed to genetically identify CD19 deficiency, which is a PID, using the RFLP method. Methods: The study was performed at Necmettin Erbakan University, Meram Medicine Faculty Hospital, Pediatric Allergy and Immunology clinic. A total of 8 patients and two healthy controls could be included in the study. A total of 8 patients and two healthy controls were included in the study, and the relevant region genotypes in the CD19 gene were determined by performing RCR-RFLP analysis. Results: CD19 deficiency was first described by us. The index case, newborn baby and mother were also included in the study. It was determined that the index case (P6) was homozygous mutant, the newborn baby (P7) and mother (P8) had heterozygous genotype. Based on this situation, one child (P1) was found to be homozygous mutant, mother (P2), father (P3) and other children (P4 and P5) had heterozygous genotype in the family, which was determined to be related to the first case. Conclusion: Rapid genetic diagnosis in patients suspected of having a known case of PID insufficiency as a result of clinical and laboratory findings carries a vital risk in terms of treatment options to be offered to patients. Although PCR-RFLP, which is a cheap, safe and fast method, is used to detect known mutations, the use of PID is rare. In our study, it has been shown that it is a method that can be used in the diagnosis of PID by determining genotypes using PCR-RFLP, and especially in terms of rapid genetic testing of family screenings.