Primary atopic disorders (PAD) are monogenic disorders caused by pathogenic gene variants encoding proteins that are key for the maintenance of a healthy skin barrier and a well-functioning immune system. Physicians face the challenge to find single, extremely rare PAD patients/families among the millions of individuals with common allergic diseases. We describe case scenarios with signature PAD. We review the literature and deduct specific clinical red flags for PAD detection. They include a positive family history and/or signs of pathological susceptibility to infections, immunodysregulation, or syndromic disease. Results of conventional laboratory and most immunological lab studies are not sufficient to make a definitive diagnosis of PAD. In the past, multistep narrowing of differential diagnoses by various immunological and other laboratory tests led to testing of single genes or gene panel analyses, which was a time-consuming and often unsuccessful approach. The implementation of whole-genomic analyses in the routine diagnostics has led to a paradigm shift. Upfront genome-wide analysis by whole genome sequencing (WGS) will shorten the time to diagnosis, save patients from unnecessary investigations, and reduce morbidity and mortality. We propose a rational, clinical landmark-based approach for deciding which cases pass the filter for carrying out early WGS. WGS result interpretation requires a great deal of caution regarding the causal relationship of variants in PAD phenotypes and absence of proof by adequate functional tests. In case of negative WGS results, a re-iteration attitude with re-analyses of the data (using the latest data base annotation)) may eventually lead to PAD diagnosis. PAD, like many other rare genetic diseases, will only be successfully managed, if physicians from different clinical specialties and geneticists interact regularly in multidisciplinary conferences.

Epidermodysplasia verruciformis (EV) is a rare genodermatosis caused by β-human papillomaviruses (HPV) in immunodeficient patients. EV is characterized by flat warts and pityriasis-like lesions and might be isolated or syndromic, associated with some other infectious manifestations. We report here three patients from two independent families, with syndromic EV for both of them. By whole exome sequencing, we found that the patients carry new homozygous variants in STK4, both leading to a premature stop codon. STK4 deficiency causes a combined immunodeficiency characterized by a broad infectious susceptibility to bacteria, viruses, and fungi. Auto-immune manifestations were also reported. Deep immunophenotyping revealed multiple cytopenia in the three affected patients, in particular deep CD4+ T cells deficiency. We report here the fourth and the fifth cases of the syndromic EV due to STK4 deficiency.

Inborn errors of immunity (IEI) are a diverse range of genetic immune system illnesses affecting the innate and/or adaptive immune systems. Variable expressivity and incomplete penetrance have been reported in IEI patients with similar clinical diagnoses or even the same genetic mutation. Among all recorded patients in the national IEI registry, 193 families with multiple cases have been recognized. Clinical, laboratory and genetic variability were compared between 451 patients with different IEI entities. The diagnosis of the first children led to the earlier diagnosis, lower diagnostic delay, timely treatment and improved survival in the second children in the majority of IEI. The highest discordance in familial lymphoproliferation, autoimmunity and malignancy were respectively observed in STK4 deficiency, DNMT3B deficiency and ATM deficiency. Regarding immunological heterogeneity within a unique family with multiple cases of IEI, the highest discordance in CD3+, CD4+, CD19+, IgM and IgA levels was observed in syndromic combined immunodeficiencies (CID), while non-syndromic CID particularly severe combined immunodeficiency (SCID) manifested the highest discordance in IgG levels. Identification of the first ATM-deficient patient can lead to improved care and better survival in the next IEI children from the same family. Intrafamilial heterogeneity in immunological and/or clinical features could be observed in families with multiple cases of IEI indicating the indisputable role of appropriate treatment and preventive environmental factors besides specific gene mutations in the variable observed penetrance or expressivity of the disease. This also emphasizes the importance of implementing genetic evaluation in all members of a family with a history of IEI even if there is no suspicion of an underlying IEI as other factors besides the underlying genetic defects might cause a milder phenotype or delay in presentation of clinical features. Thus, affected patients could be timely diagnosed and treated, and their quality of life and survival would improve.

Serine/threonine kinase 4 deficiency (STK4 or MST1, OMIM:614868) is an autosomal recessive (AR) combined immunodeficiency that can present with skin lesions such as epidermodysplasia verruciformis-like lesions (EVLL). Herein, we describe a 17-year-old male patient born from consanguineous parents presenting with recurrent respiratory infections, verruciform plaques, poikiloderma, chronic benign lymphoproliferation, and Sjögren syndrome with suspected interstitial lymphocytic pneumonia.

Unusual viral skin infections might be the first clinical manifestation in children with an inborn error of immunity (IEI). We performed a prospective study from 1 October 2017 to 30 September 2021, at the Department of Pediatric Infectious Diseases and Clinical Immunity of Ibn Rochd University Hospital-Casablanca. During this period, on 591 patients newly diagnosed with a probable IEI, eight of them (1.3%), from six independent families, had isolated or syndromic unusual viral skin infections, which were either profuse, chronic or recurrent infections, and resistant to any treatment. The median age of disease onset was nine years old and all patients were born from a first-degree consanguineous marriage. By combining clinical, immunological and genetic investigations, we identified GATA2 deficiency in one patient with recalcitrant profuse verrucous lesions and monocytopenia (1/8) and STK4 deficiency in two families with HPV lesions, either flat or common warts, and lymphopenia (2/8), as previously reported. We also identified COPA deficiency in twin sisters with chronic profuse Molluscum contagiosum lesions, pulmonary diseases and microcytic hypochromic anemia (2/8). Finally, we also found one patient with chronic profuse MC lesions and hyper IgE syndrome, (1/8) and two patients with either recalcitrant profuse verrucous lesions or recurrent post-herpetic erythema multiforme and a combined immunodeficiency (2/8) with no genetic defect identified yet. Raising clinicians awareness that infectious skin diseases might be the consequence of an inborn error of immunity would allow for optimized diagnosis, prevention and treatment of patients and their families.