Megakaryoblastic leukemia 1 (MKL1) promotes the regulation of essential cell processes, including actin cytoskeletal dynamics, by coactivating serum response factor. Recently, the first human with MKL1 deficiency, leading to a novel primary immunodeficiency, was identified. We report a second family with 2 siblings with a homozygous frameshift mutation in MKL1. The index case died as an infant from progressive and severe pneumonia caused by Pseudomonas aeruginosa and poor wound healing. The younger sibling was preemptively transplanted shortly after birth. The immunodeficiency was marked by a pronounced actin polymerization defect and a strongly reduced motility and chemotactic response by MKL1-deficient neutrophils. In addition to the lack of MKL1, subsequent proteomic and transcriptomic analyses of patient neutrophils revealed actin and several actin-related proteins to be downregulated, confirming a role for MKL1 as a transcriptional coregulator. Degranulation was enhanced upon suboptimal neutrophil activation, whereas production of reactive oxygen species was normal. Neutrophil adhesion was intact but without proper spreading. The latter could explain the observed failure in firm adherence and transendothelial migration under flow conditions. No apparent defect in phagocytosis or bacterial killing was found. Also, monocyte-derived macrophages showed intact phagocytosis, and lymphocyte counts and proliferative capacity were normal. Nonhematopoietic primary fibroblasts demonstrated defective differentiation into myofibroblasts but normal migration and F-actin content, most likely as a result of compensatory mechanisms of MKL2, which is not expressed in neutrophils. Our findings extend current insight into the severe immune dysfunction in MKL1 deficiency, with cytoskeletal dysfunction and defective extravasation of neutrophils as the most prominent features.

A study-level meta-analysis has shown that proton magnetic resonance spectroscopy is a promising prognostic marker in neonatal hypoxic-ischemic encephalopathy. An individual patient data meta-analysis could yield a prognostic tool with improved accuracy enabling well-founded clinical decisions. Our request to share patient data remained unanswered by five out of 18 research groups. Another four declined collaboration for various reasons, including own reanalysis of the data, and lack of parental consent. With less than 40% of the individual patient data available, we refrained from pursuing the proposed study. As future patients may benefit from it, policies mandating data sharing should be introduced.

6-Mercaptopurine (6-MP) maintains remission in pediatric Crohn's disease (CD). Azathioprine, a prodrug of 6-MP, is used for maintenance of remission of CD in Europe. We evaluated to what extent azathioprine is used in newly diagnosed pediatric CD patients and whether maintenance of remission differed between patients using azathioprine or not. Charts of children (diagnosed 1998-2003, follow-up > or = 18 mo) were reviewed. Active disease was defined as Pediatric Crohn's Disease Activity Index (PCDAI) greater than 10 or systemic corticosteroid use. Remission was defined as PCDAI 10 or less without use of corticosteroids. Eighty-eight children (55M/33F, age 12 +/- 3 yr) were included. Seventy-two (82%) patients received azathioprine during the follow-up period (38 +/- 17 mo). Patients diagnosed after 2000 received azathioprine significantly earlier during the course of disease compared with those diagnosed earlier (median, at 233 vs. 686 days; P < 0.05). At initial presentation, moderate-severe disease activity and prescription of corticosteroids were more prevalent in patients using azathioprine compared with nonazathioprine patients (75% vs. 52%; P < 0.05; and 89% vs. 58%; P < 0.005, respectively). Duration of corticosteroid use was longer in patients receiving azathioprine (232 vs. 168 days; P < 0.005). Median maintenance of first remission in patients who initially used corticosteroids, however, was longer in patients receiving azathioprine compared with nonazathioprine patients (PCDAI, 544 vs. 254 days, P = 0.08; corticosteroid free, 575 vs. 259 days, P < 0.05, respectively). We conclude that, since 2000, azathioprine is being introduced earlier in the treatment of newly diagnosed pediatric CD patients. The use of azathioprine is associated with prolonged maintenance of the first remission.

Tinea capitis is a common skin infection that should be considered in any type of scalp lesion. It requires systemic treatment, and inappropriate and delayed treatment can result in the development of kerion celsi, with sometimes devastating consequences.