Utilization of next-generation sequencing to define the role of heterozygous FOXN1 variants in immunodeficiency.

Background: Forkhead box protein N1 (FOXN1) transcription factor plays an essential role in the development of thymic epithelial cells, required for T-cell differentiation, maturation, and function. Biallelic pathogenic variants in FOXN1 cause severe combined immunodeficiency (SCID). More recently, heterozygous variants in FOXN1, identified by restricted gene panels, were also implicated with causing a less severe and variable immunodeficiency. Objective: We undertook longitudinal follow-up and advanced genetic investigations, including whole exome sequencing and whole genome sequencing, of newborns with a heterozygous variant in FOXN1. Methods: Five patients (3 female, 2 male) have been followed since they were first detected with low T-cell receptor excision circles during newborn screening for SCID. Patients underwent immune evaluation as well as genetic testing, including a primary immunodeficiency panel, whole exome sequencing, and whole genome sequencing in some cases. Results: Median follow-up time was 6.5 years. Initial investigations revealed low CD3+ T lymphocytes in all patients. One patient presented with extremely low lymphocyte counts and depressed phytohemagglutinin responses leading to a tentative diagnosis of SCID. Over a period of 2 years, CD3+ T-cell counts rose, although in some patients it remained borderline low. One of 5 children continues to experience recurrent upper respiratory infections and asthma episodes. The remaining are asymptomatic except for eczema in 2 of 5 cases. Lymphocyte proliferation responses to phytohemagglutinin were initially low in 3 patients but normalized by age 10 months. In 3 of 5 cases, T lymphocyte counts remain low/borderline low. Conclusion: In cases of monoallelic FOXN1 variants, using whole exome sequencing and whole genome sequencing to rule out possible other significant pathogenic variants allowed us to proceed with confidence in a conservative manner, even in extreme cases consistent with newborn screen-positive early presentation of SCID.

A Novel De Novo NFKBIA Missense Mutation Associated to Ectodermal Dysplasia with Dysgammaglobulinemia.

Background: Inborn errors of immunity (IEIs) are comprised of heterogeneous groups of genetic disorders affecting immune function. In this report, a 17-month-old Malay patient suspected of having Hyper IgM syndrome, a type of IEIs, was described. However, the diagnosis of Hyper IgM syndrome was excluded by the normal functional studies and the mild features of ectodermal dysplasia observed from a further clinical phenotype inspection. Methods: Whole-exome sequencing (WES) was performed to unravel the causative mutation in this patient. Results: The variant analysis demonstrated a novel missense mutation in NFKBIA (NM_020529:c.94A > T,NP_065390:p.Ser32Cys) and was predicted as damaging by in silico prediction tools. The NFKBIA gene encodes for IκBα, a member of nuclear factor kappa B (NF-κB) inhibitors, playing an important role in regulating NF-κB activity. The mutation occurred at the six degrons (Asp31-Ser36) in IκBα which were evolutionarily conserved across several species. Prediction analysis suggested that the substitution of Ser32Cys may cause a loss of the phosphorylation site at residue 32 and a gain of the sumoylation site at residue 38, resulting in the alteration of post-translational modifications of IκBα required for NF-κB activation. Conclusion: Our analysis hints that the post-translational modification in the NFKBIA Ser32Cys mutant would alter the signaling pathway of NF-κB. Our findings support the usefulness of WES in diagnosing IEIs and suggest the role of post-translational modification of IκBα.

Parental reports of behavioural outcome among paediatric leukaemia survivors in Malaysia: a single institution experience.

OBJECTIVES: To determine the behavioural impact of chemotherapy in survivors of acute lymphoblastic leukaemia (ALL) treated with chemotherapy only and to identify treatment-related or sociodemography-related factors that might be associated with behavioural outcome. METHODS: We examined 57 survivors of childhood ALL, who were off treatment for at least 2 years and were in remission, aged 4-18 years, and 221 unrelated healthy controls. The Child Behaviour Checklist (CBCL) parent report was used either in English or in Bahasa Malaysia (the national language of Malaysia) to assess the behavioural outcome. RESULTS: Childhood ALL survivors had significantly higher scores on externalising behaviour on the CBCL parent report than did controls. Higher problem scores were found in ALL survivors with single parents on 'total problems' (P = 0.03) and subscales 'withdrawn' (P = 0.03), 'social problems' (P < 0.01) and 'delinquent behaviour' (P = 0.03) than in survivors with married parents. Significant associations were seen between a lower education level of the father and the variables representing internalising (withdrawn, anxious/depressed) and externalising (aggressive behaviour). We observed trends on higher scores in all scales in ALL survivors with single parents than in controls with single parents or with fathers with low education level, especially primary education only. CONCLUSIONS: Malaysian childhood ALL survivors had a significantly increased risk for externalising behavioural problems, and there was a trend towards increased risk of problems in many other behavioural scales. Understanding the sociocultural dimension of patients' health is important to be able to design the most appropriate remedy for problem behaviours detected in this multi-ethnic population.