Sequence variants underlying severe combined immunodeficiency and leukocyte adhesion deficiency type 1 in six consanguineous families.

Inborn errors of immunity (IEI) are defined as genetic disorders affecting the immune system and resulting in diverse clinical signs and symptoms. Despite the lack of diagnosis and unavailability of IEI estimation in the Pakistani population, consanguinity is exacerbating its prevalence. The current study focuses on severe combined immunodeficiency (SCID) and leukocyte adhesion deficiency type 1 (LAD1). SCID is associated with the life-threatening symptoms developing at post-birth. LAD1 is clinically characterized by recurrent bacterial infections related to the skin, mouth, and respiratory tract owing to impaired leukocytes. Herein, in six consanguineous families, flow cytometry was used to evaluate the patient's immune status. Whole-exome sequencing (WES) was then conducted to search for the causative variations in immunodeficiency genes. Sanger sequencing was used to assess the segregation of the variants with the disorder within the families. Sequence analysis revealed five homozygous variants in four different causative genes. This included four novel nonsense variants in CD70 p.(Thr126Profs*33), CD3e p.(Trp151*), IL7R p.(Val138Ilefs*10), and ITGB2 p.(Ser627Valfs*61), and one previously reported in ITGB2 p.(Cys62*). In one of the families, two variants in two different genes, including DNAH6 p.(Tyr2653His) and NIPAL4 p.(Gly121Ser), were detected in an unclassified patient. All the identified variants were found in a homozygous state in the patient but in a heterozygous state in the available parents. The study will facilitate the diagnosis and management of IEI patients.

Mutational analysis in different genes underlying severe combined immunodeficiency in seven consanguineous Pakistani families.

BACKGROUND: Severe Combined Immunodeficiency (SCID) is an autosomal recessive inborn error of immunity (IEI) characterized by recurrent chest and gastrointestinal (GI) infections and in some cases associated with life-threatening disorders. METHODOLOGY AND RESULTS: This current study aims to unwind the molecular etiology of SCID and also extended the patients' phenotype associated with identified particular variants. Herein, we present 06 disease-causing variants identified in 07 SCID-patients in three different SCID related genes. Whole Exome Sequencing (WES) followed by Sanger Sequencing was employed to explore genetic variations. The results included identification of two previously reported heterozygous variants in homozygous form for the first time in RAG1gene [(p.Arg410Gln);(p.Arg737His)], followed by a recurrent variant (p.Trp959*) in RAG1, a novel variant in IL2RG (p.Asp48Lfs*24), a recurrent variant in IL2RG (p.Gly271Glu) and a recurrent variant in DCLRE1C (p.Arg191*) gene. CONCLUSION: To conclude, the immune-profiling and WES revealed two novel, two as homozygous state for the first time, and two recurrent disease causing variants contributing valuably to our existing knowledge of SCID.