Tyrosinemia type 1 in pediatric nephrology: Not always straightforward

The main clinical features of tyrosinemia type 1 usually appear in the first months of life, including fever, diarrhea, vomiting, liver involvement, growth failure, and renal proximal tubulopathy with subsequent hypophosphatemic rickets. An early diagnosis is crucial in order to provide specific management and to prevent complications. Here, we report on two cases referred primarily to pediatric nephrologists for the diagnosis of “neonatal tubulopathy” and management of “X-linked hypophosphatemia (XLH),” respectively. Our aim is to emphasize that (1) even a mixed tubulopathy can reveal tyrosinemia, and (2) tyrosinemia is a classic differential diagnosis of XLH that should not be forgotten, especially in the era of the anti-FGF23 burosumab.     

Rapid identification of atypical variant of plasma butyrylcholinesterase by PCR.

Human butyrylcholinesterase is the enzyme responsible of mivacurium and succinylcholine metabolism, which may be significantly impaired when mutation Asp70Gly is found in patients. We describe a simple PCR method for the detection of this variant. Thirteen out of sixteen patients tested after prolonged apnea were positive for the presence of this mutation (50.0% homozygotes and 31.3% heterozygotes), suggesting that this test contributes to the explanation of some clinical events and to their prevention in relatives of these patients.     

Is cholic acid responsible for embryo-toxicity of the post-receptive uterine environment?

HPLC analysis of the embryo-toxic fraction of human uterinefluid, collected between the 22nd and 25th days of the menstrualcycle, revealed the presence of cholic acid at high concentrations.It is suggested that cholic acid could be responsible for theembryo-toxicity of the uterine environment, which follows thereceptive period for implantation.