Adenosine deaminase 2 (ADA2) deficiency is an auto-inflammatory disease due to mutations in cat eye syndrome chromosome region candidate 1 (CECR1) gene, currently named ADA2. The disease has a wide clinical spectrum encompassing early-onset vasculopathy (targeting skin, gut and central nervous system), recurrent fever, immunodeficiency and bone marrow dysfunction. Different therapeutic options have been proposed in literature, but only steroids and anti-cytokine monoclonal antibodies (such as tumor necrosis factor inhibitor) proved to be effective. If a suitable donor is available, hematopoietic stem cell transplantation (HSCT) could be curative. Here we describe a case of ADA2 deficiency in a 4-year-old Caucasian girl. The patient was initially classified as autoimmune neutropenia and then she evolved toward an autoimmune lymphoproliferative syndrome (ALPS)-like phenotype. The diagnosis of ALPS became uncertain due to atypical clinical features and normal FAS-induced apoptosis test. She was treated with G-CSF first and subsequently with immunosuppressive drugs without improvement. Only HSCT from a 9/10 HLA-matched unrelated donor, following myeloablative conditioning, completely solved the clinical signs related to ADA2 deficiency. Early diagnosis in cases presenting with hematological manifestations, rather than classical vasculopathy, allows the patients to promptly undergo HSCT and avoid more severe evolution. Finally, in similar cases highly suspicious for genetic disease, it is desirable to obtain molecular diagnosis before performing HSCT, since it can influence the transplant procedure. However, if HSCT has to be performed without delay for clinical indication, related donors should be excluded to avoid the risk of relapse or partial benefit due to a hereditary genetic defect.

Breast milk and colostrum are the first feeding sources for a child, providing nutrients, growth factors and immunological components, which are crucial for the newborn's correct development and health. Length of exclusive breastfeeding and time of solid foods introduction is a key factor that may influence allergy development. There is an emerging evidence of a relationship between breastfeeding, milk composition and lower risk of chronic diseases, such as diabetes, obesity, hypertension and allergies. This review examines current evidence regarding humoral and cellular characteristics of breast-milk, and potential role of environment, maternal diet and breastfeeding on the allergy development in children.

The sonografic diagnosis of acute cholecystitis may be achieved by registering only three standardized US signs. Nevertheless, in patients admitted for symptomatic gallstones, US is of some utility in less than half of those patients.

Strategies to prevent or reduce the risk of allergic diseases are needed. The time of exclusive breastfeeding and introduction of solid foods is a key factor that may influence the development of allergy. For this reason, the aim of this review was to examine the association between exposure to solid foods in the infant's diet and the development of allergic diseases in children. Classical prophylactic feeding guidelines recommended a delayed introduction of solids for the prevention of atopic diseases. Is it really true that a delayed introduction of solids (after the 4th or 6th month) is protective against the development of eczema, asthma, allergic rhinitis and food or inhalant sensitisation? In recent years, many authors have found that there is no statistically significant association between delayed introduction of solids and protection for the development of allergic diseases. Furthermore, late introduction of solid foods could be associated with increased risk of allergic sensitisation to foods, inhalant allergens and celiac disease in children. Tolerance may be driven by the contact of the mucosal immune system with the allergen at the right time of life; the protective effects seem to be enhanced by the practice of the breastfeeding at the same time when weaning is started. Therefore, recent guidelines propose a "window" approach for weaning practice starting at the 17th week and introducing almost all foods within the 27th week of life to reduce the risk of chronic diseases such as allergic ones and the celiac disease. Guidelines emphasize the role of breastfeeding during the weaning practice.

There is increasing evidence that vitamin D regulates immune responses. There is also epidemiological evidence of a relationship between vitamin D deficiency and development of asthma. In addition, several epidemiological studies suggest that low levels of vitamin D during pregnancy and early life are inversely associated with the risk of developing respiratory infections and wheezing in childhood. Vitamin D also seems to reduce asthma exacerbation and increase the response to glucocorticoids. These findings have led to considering a possible link between the occurrence of allergic respiratory diseases and low levels of vitamin D. However, the precise role of vitamin D in the pathogenesis of asthma still remains unclear, emphasizing the need for well-designed trials on vitamin D supplementation to decipher its role in preventing and/or managing the disease. This review examines the relationship that exists between vitamin D deficiency and childhood wheezing and asthma.

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