STK4 (MST1) deficiency in two siblings with autoimmune cytopenias: A novel mutation.

Combined immunodeficiencies (CIDs) are heterogeneous group of disorders characterized by abrogated/impaired T cell development and/or functions that resulted from diverse genetic defects. In addition to the susceptibility to infections with various microorganisms, the patients may have lymphoproliferation, autoimmunity, inflammation, allergy and malignancy. Recently, three groups have independently reported patients having mutations in STK4 gene that cause a novel autosomal recessive (AR) CID. We describe here two siblings with a novel STK4 mutation identified during the evaluation of a group of patients with features highly overlapping with those of DOCK-8 deficiency, a form of AR hyperimmunoglobulin E syndrome. The patients' clinical features include autoimmune cytopenias, viral skin (molluscum contagiosum and perioral herpetic infection) and bacterial infections, mild onychomycosis, mild atopic and seborrheic dermatitis, lymphopenia (particularly CD4 lymphopenia), and intermittent mild neutropenia. Determination of the underlying defect and reporting the patients are required for the description of the phenotypic spectrum of each immunodeficiency.

IL-12Rß1 deficiency: mutation update and description of the IL12RB1 variation database.

IL-12Rß1 deficiency is an autosomal recessive disorder characterized by predisposition to recurrent and/or severe infections caused by otherwise poorly pathogenic mycobacteria and salmonella. IL-12Rß1 is a receptor chain of both the IL-12 and the IL-23 receptor and deficiency of IL-12Rß1 thus abolishes both IL-12 and IL-23 signaling. IL-12Rß1 deficiency is caused by bi-allelic mutations in the IL12RB1 gene. Mutations resulting in premature stop codons, such as nonsense, frame shift, and splice site mutations, represent the majority of IL-12Rß1 deficiency causing mutations (66%; 46/70). Also every other morbid mutation completely inactivates the IL-12Rß1 protein. In addition to disease-causing mutations, rare and common variations with unknown functional effect have been reported in IL12RB1. All these variants have been deposited in the online IL12RB1 variation database (www.LOVD.nl/IL12RB1). In this article, we review the function of IL-12Rß1 and molecular genetics of human IL12RB1.

Hereditary C1q deficiency: a new family with C1qA deficiency.

Hereditary deficiency of complement component C1q is a rare genetic disorder with susceptibility to recurrent infections with polysaccharide-containing encapsulated microorganisms and a high prevalence of autoimmune diseases, most often systemic lupus erythematosus (SLE). Here, we report a 29-month-old boy who presented with facial rash and history of early death of a sibling with infections, who was found to have a selective deficiency of C1q. The facial rash was composed of patchy erythematous plaques and centrally hypopigmented macules and desquamation. Two siblings had died of severe bacterial infections and his uncle had died of meningitis. Molecular study disclosed a homozygous point mutation in the C1qA chain gene. Five members of the family, including the parents and three healthy siblings, were heterozygous for this mutation.