Genetic Diagnosis of Inborn Errors of Immunity in an Emerging Country: a Retrospective Study of 216 Moroccan Patients.

PURPOSE: Genetic testing provides great support to validate the clinical diagnosis of inborn errors of immunity (IEI). However, the high cost and advanced technology make these tests inaccessible to a large proportion of patients in low-income countries. In the present study, we aim to evaluate the Moroccan experience in genetic testing and to report the main molecular features and difficulties encountered in genetic diagnosis. METHODS: We performed a multi-center retrospective analysis of all patients with a molecular diagnosis and registered in the national registry between 2010 and 2022. To estimate the impact of the newly identified mutations, we calculated the Combined Annotation Dependent Depletion (CADD) score and the mutation significance cutoff (MSC) for each variant. RESULTS: A total of 216 (29%) patients received a genetic diagnosis out of 742 patients with IEI included in the registry. All genetic tests were performed in the context of thesis projects (40%) or international collaborations (60%). A set of 55 genetic defects were identified, including 7 newly reported: SNORA31, TBX21, SPPL2A, TYK2, RLTPR, ZNF341, and STAT2 GOF. Genetic diagnoses were more frequent in the defects of innate and intrinsic immunity with a percentage of 78%, while antibody deficiencies had a lower frequency with a percentage of 17.5%. Only one genetic diagnosis has been made in the complement deficiency group. The most commonly used molecular techniques were Sanger sequencing (37%) followed by targeted gene sequencing (31%). CONCLUSION: The thesis projects and collaborations were beneficial as they allowed us to provide a definitive genetic diagnosis to 29% of the patients and to contribute to the identification of new genetic defects and mutations. These results offer insight into the progress made in genetic diagnoses of IEI in Morocco, which would provide a baseline for improving the clinical management of patients with IEI.

Clinical and Immunological Features of 96 Moroccan Children with SCID Phenotype: Two Decades' Experience.

Severe combined immunodeficiency (SCID) is a heterogeneous group of primary immunodeficiency diseases (PIDs) characterized by a lack of autologous T lymphocytes. This severe PID is rare, but has a higher prevalence in populations with high rates of consanguinity. The epidemiological, clinical, and immunological features of SCIDs in Moroccan patients have never been reported. The aim of this study was to provide a clinical and immunological description of SCID in Morocco and to assess changes in the care of SCID patients over time. This cross-sectional retrospective study included 96 Moroccan patients referred to the national PID reference center at Casablanca Children's Hospital for SCID over two decades, from 1998 to 2019. The case definition for this study was age < 2 years, with a clinical phenotype suggestive of SCID, and lymphopenia, with very low numbers of autologous T cells, according to the IUIS Inborn Errors of Immunity classification. Our sample included 50 male patients, and 66% of the patients were born to consanguineous parents. The median age at onset and diagnosis were 3.3 and 6.5 months, respectively. The clinical manifestations commonly observed in these patients were recurrent respiratory tract infection (82%), chronic diarrhea (69%), oral candidiasis (61%), and failure to thrive (65%). The distribution of SCID phenotypes was as follows: T-B-NK+ in 44.5%, T-B-NK- in 32%, T-B+NK- in 18.5%, and T-B+NK+ in 5%. An Omenn syndrome phenotype was observed in 15 patients. SCID was fatal in 84% in the patients in our cohort, due to the difficulties involved in obtaining urgent access to hematopoietic stem cell transplantation, which, nevertheless, saved 16% of the patients. The autosomal recessive forms of the clinical and immunological phenotypes of SCID, including the T-B-NK+ phenotype in particular, were more frequent than those in Western countries. A marked improvement in the early detection of SCID cases over the last decade was noted. Despite recent progress in SCID diagnosis, additional efforts are required, for genetic confirmation and particularly for HSCT.