Whole exome sequencing identified a novel splice donor site variant in interleukin 2 receptor alpha chain

Mutational spectrum of CFTR in cystic fibrosis patients with gastrointestinal and hepatobiliary manifestations

BACKGROUND

Cystic fibrosis (CF) is a rare and debilitating autosomal recessive disorder. It hampers the normal function of various organs and causes severe damage to the lungs, and digestive system leading to recurring pneumonia. Cf also affects reproductive health eventually may cause infertility. The disease manifests due to genetic aberrations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This study aimed to screen for CFTR gene variants in Pakistani CF patients representing variable phenotypes.

METHODS

Clinical exome and Sanger sequencing were performed after clinical characterization of 25 suspected cases of CF (CF1-CF25). ACMG guidelines were followed to interpret the clinical significance of the identified variants.

RESULTS

Clinical investigations revealed common phenotypes such as pancreatic insufficiency, chest infections, chronic liver and lung diseases. Some patients also displayed symptoms like gastroesophageal reflux disease (GERD), neonatal cholestasis, acrodermatitis, diabetes mellitus, and abnormal malabsorptive stools. Genetic analysis of the 25 CF patients identified deleterious variants in the CFTR gene. Notably, 12% of patients showed compound heterozygous variants, while 88% had homozygous variants. The most prevalent variant was p. (Met1Thr or Met1?) at 24%, previously not reported in the Pakistani population. The second most common variant was p. (Phe508del) at 16%. Other variants, including p. (Leu218*), p. (Tyr569Asp), p. (Glu585Ter), and p. (Arg1162*) were also identified in the present study. Genetic analysis of one of the present patients showed a pathogenic variant in G6PD in addition to CFTR.

CONCLUSION

The study reports novel and reported variants in the CFTR gene in CF patients in Pakistani population having distinct phenotypes. It also emphasizes screening suspected Pakistani CF patients for the p. (Met1Thr) variant because of its increased observance and prevalence in the study. Moreover, the findings also signify searching for additional pathogenic variants in the genome of CF patients, which may modify the phenotypes. The findings contribute valuable information for the diagnosis, genetic counseling, and potential therapeutic strategies for CF patients in Pakistan.

Infections in Disorders of Immune Regulation

Primary immune regulatory disorders (PIRDs) constitute a spectrum of inborn errors of immunity (IEIs) that are primarily characterized by autoimmunity, lymphoproliferation, atopy, and malignancy. In PIRDs, infections are infrequent compared to other IEIs. While susceptibility to infection primarily stems from antibody deficiency, it is sometimes associated with additional innate immune and T or NK cell defects. The use of immunotherapy and chemotherapy further complicates the immune landscape, increasing the risk of diverse infections. Recurrent sinopulmonary infections, particularly bacterial infections such as those associated with staphylococcal and streptococcal organisms, are the most reported infectious manifestations. Predisposition to viral infections, especially Epstein-Barr virus (EBV)-inducing lymphoproliferation and malignancy, is also seen. Notably, mycobacterial and invasive fungal infections are rarely documented in these disorders. Knowledge about the spectrum of infections in these disorders would prevent diagnostic delays and prevent organ damage. This review delves into the infection profile specific to autoimmune lymphoproliferative syndrome (ALPS), Tregopathies, and syndromes with autoimmunity within the broader context of PIRD. Despite the critical importance of understanding the infectious aspects of these disorders, there remains a scarcity of comprehensive reports on this subject.