Defective monocyte plasticity and altered cAMP pathway characterize USB1-mutated poikiloderma with neutropenia Clericuzio type.

Poikiloderma with neutropenia (PN) Clericuzio type (OMIM #604173) is a rare disease with areas of skin hyper- and hypopigmentation caused by biallelic USB1 variants. The current study was spurred by poor healing of a perianal tear wound in one affected child homozygous for c.266-1G>A (p.E90Sfster8) mutation, from a family reported previously. Treatment with G-CSF/CSF3 or GM-CSF/CSF2 transiently increased neutrophil/monocytes count with no effect on wound healing. Analysis of peripheral blood revealed a lack of non-classical (CD14+/- CD16+ ) monocytes, associated with a systemic inflammatory cytokine profile, in the two affected brothers. Importantly, despite normal expression of cognate receptors, monocytes from PN patients did not respond to M-CSF or IL-34 in vitro, as determined by cytokine secretion or CD16 expression. RNAseq of monocytes showed 293 differentially expressed genes, including significant downregulation of GATA2, AKAP6 and PDE4DIP that are associated with leucocyte differentiation and cyclic adenosine monophosphate (cAMP) signalling. Notably, the plasma cAMP was significantly low in the PN patients. Our study revealed a novel association of PN with a lack of non-classical monocyte population. The defects in monocyte plasticity may contribute to disease manifestations in PN and a defective cAMP signalling may be the primary effect of the splicing errors caused by USB1 mutation.

Hematuria as an adverse outcome following provocative growth hormone stimulation testing in children.

BACKGROUND: Provocative growth hormone (GH) stimulation testing is used to evaluate short stature and growth failure in children. Agents commonly used for testing include clonidine, arginine and glucagon. While stimulation testing is generally considered safe, gross hematuria has been described as a rare idiopathic complication of GH stimulation testing. This study was designed to estimate the incidence of both microscopic and macroscopic hematuria following GH testing with different provocative agents. METHODS: Subjects undergoing GH stimulation testing were invited to participate in the study. Prior to testing, vital signs were measured and baseline point-of-care (POC) urinalysis was done. The subjects performed urine testing at home on days 1, 2, 3 and 7 following GH stimulation studies. Families notified the study team with any positive findings and returned the data collection tool by mail. RESULTS: In total, 34 subjects aged 11.14±2.71 years (91.2% male) completed the study. Agents used in provocative testing included arginine (73.5%), clonidine (94.1%) and glucagon (32.4%). Three subjects developed hematuria after GH stimulation testing (clonidine/arginine). The hematuria resolved by 7 days after testing. Additional adverse effects included nausea, vomiting and hypotension. CONCLUSIONS: In this study of children undergoing GH testing, hematuria was identified in three subjects. This study demonstrates that side effects to agents used for GH testing are self-limited, yet not rare, and should be discussed with patients and families prior to stimulation testing.