The upstream and downstream Alu repeat sequences, delimiting the g.15410_16542del deleted region (in gray), are indicated in red. The X\linked SCID (X\SCID), caused by mutations Pantoprazole (Protonix) in gene encoding the common gamma\chain (\chain), is the most frequent form of the disease and its clinical phenotype is comparable to that of autosomal recessive SCID (AR\SCID) caused by Janus kinase 3 (gene. For one of these, the g.15410_16542del, we suggest a mechanism of recombination between Alu elements as cause of deletion. This mutation was found in two unrelated patients and a possible founder effect was investigated. Protein and molecular studies were performed to have a definitive diagnosis in these patients. 2.?MATERIALS AND METHODS 2.1. Patients We report four unrelated Italian patients (2 females and 2 males) with SCID phenotype. In Table?1, we reported immunological data from all patients. The pedigree analysis of the four different families did not reveal any case of parental consanguinity. Informed consent was obtained from the patients and controls parents for immunological and genetic investigation. Table 1 Immunological characteristics of severe combined immunodeficiency (SCID) patients poor responsive to antibiotics therapy. During this hospitalization, the total lymphocyte count of 315/mm3 (CD3 21%; CD4 12%; CD8 8%; CD19 58%; CD57 2%; CD16 8%) and a low dosage of immunoglobulines induced the suspect of an immunodeficit. He was transferred at age of 10?months to our hospital in poor general conditions, to be investigated for immunodeficiency. A chest radiograph and a total body TC were performed in which none particular alteration was highlighted except indicators of ongoing otitis and normal mediastinal structures were reported. Allogeneic haploidentical HSCT from his mother was successfully performed at the age of 12?months. Eleven years after HSCT, the patient is in general good condition and shows adequate immunological function. Patient 2 (Pt2) was a girl with a history of a phlegmon around the thigh Pantoprazole (Protonix) at 4?months of age. She was admitted to our hospital because of severe SRV bronchiolitis with acute respiratory distress, and an immunodeficiency was suspected although a lymphocyte absolute count of 2,420/ml was detected. She underwent a successful HSCT from her HLA\identical sister at the age of 7?months. Eleven years after HSCT, she maintains good clinical condition and immunoreconstitution. Patient 3 (Pt3) was a girl hospitalized at 4?months of age due to failure to thrive. She was discharged 3?days later with a suspect of cow milk allergy. Because of persistent vomiting, she was subsequently admitted to our hospital and discharged with a diagnosis of urinary contamination. However, she was readmitted a few Pantoprazole (Protonix) days later for wheezing and cough. A rapidly progressive respiratory failure with a picture of interstitial pulmonary picture occurred, necessitating mechanical ventilation. The rapid clinical deterioration suggested a diagnosis of SCID confirmed by immunological phenotype and molecular analysis. Bronchoalveolar lavage (BAL) and tracheal aspirate (TA) for bacteria, EBV, CMV, adenovirus, influenzae, parainfluenzae resulted unfavorable. Pantoprazole (Protonix) Treatment with antibiotics, intravenous immunoglobulins, trimethoprim\sulfamethoxazole, fuconazole, acyclovir, and antiviral prophylaxis was promptly started without any improvement. She died one month after haploidentical HSCT. Patient 4 (Pt4) was a young man given birth to at term. He was well until 4?months of age when he was brought to our attention due to acute respiratory failure, without fever. He had history of long\lasting cough and a growth arrest in the last month. The chest X\ray performed revealed an interstitial pneumonia and an antibiotic therapy was started unsuccessfully. Immunological investigations showed a hypogammaglobulinemia and a T and NK lymphopenia despite normal lymphocyte count. Chimerism analysis did not reveal maternal T cells. Due to the detection of Pneumocystis Jirovecii in tracheal aspirate Trimethoprim\sulfamethoxazole and corticosteroids were started with fast clinical improvement. Allogenic haploidentical HSCT from her mother was successfully performed at the age of 8?months. Seventeen months after HSCT, he did FST not present severe complications and he.