Spontaneous adverse drug reaction reports for neonates and infants in the UK 2001-2010: content and utility analysis.

AIMS: The UK Medicines and Healthcare products Regulatory Agency (MHRA) runs a national spontaneous reporting system (Yellow Card [YC] Scheme) to collect 'suspected' adverse drug reaction (ADR) data. We aim to describe the content and utility of YC reports received for patients aged <2 years. METHODS: Data on all ADRs reported using YC in infants aged <2 years from the years 2001-10 were supplied by the MHRA. RESULTS: For infants age <2 years, 3496 suspected ADRs were reported using YC (paternal medication pre-conception n = 3, transplacental n = 246, transmammary n = 30, neonates n = 97, infant n = 477, and vaccinations n = 2673), averaging 0.96 YC per day. There was a male preponderance (male 49.1%, female 44.4%, unknown 6.5%), and only 34 (1.0%) of YC reports stated a gestational age. The medications most frequently reported were: transplacental and transmammary (fluoxetine, n = 21 and n = 4 respectively), neonate (swine flu vaccine, n = 8) infant (oseltamivir, n = 37) and vaccines (meningococcal vaccine, n = 693). Paternal, transmammary, neonatal and infant YC did not reflect clinical concerns raised by the UK regulator. Transplacental and vaccination reports did correlate with some of the changes in practice and clinical alerts received. CONCLUSIONS: The frequency of YC reports for those <2 years is low, neonates are poorly represented, and recording of gestational age is poor. With the exception of vaccinations, spontaneous reports alone are not currently generating the data required, and important safety messages from the regulator do not match reporting patterns. Additional reporting strategies are required to improve the quantity and quality of suspected ADR data in young children.

Identification of a novel loss-of-function PHEX mutation, Ala720Ser, in a sporadic case of adult-onset hypophosphatemic osteomalacia.

Adults presenting with sporadic hypophosphatemia and elevations in circulating fibroblast growth factor-23 (FGF23) concentrations are usually investigated for an acquired disorder of FGF23 excess such as tumor induced osteomalacia (TIO). However, in some cases the underlying tumor is not detected, and such patients may harbor other causes of FGF23 excess. Indeed, coding-region and 3'UTR mutations of phosphate-regulating neutral endopeptidase (PHEX), which encodes a cell-surface protein that regulates circulating FGF23 concentrations, can lead to alterations in phosphate homeostasis, which are not detected until adulthood. Here, we report an adult female who presented with hypophosphatemic osteomalacia and raised serum FGF23 concentrations. The patient and her parents, who were her only first-degree relatives, had no history of rickets. The patient was thus suspected of having TIO. However, no tumor had been identified following extensive localization studies. Mutational analysis of the PHEX coding-region and 3'UTR was undertaken, and this revealed the patient to be heterozygous for a novel germline PHEX mutation (c.2158G>T; p.Ala720Ser). In vitro studies involving the expression of WT and mutant PHEX proteins in HEK293 cells demonstrated the Ala720Ser mutation to impair trafficking of PHEX, with ~20% of the mutant protein being expressed at the cell surface, compared to ~80% cell surface expression for WT PHEX (p<0.05). Thus, our studies have identified a pathogenic PHEX mutation in a sporadic case of adult-onset hypophosphatemic osteomalacia, and these findings highlight a role for PHEX gene analysis in some cases of suspected TIO, particularly when no tumor has been identified.