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Genes and hearing loss
Many cases of unexplained deafness have a genetic origin, even when there is no family history. Until recently, genetic testing has been unrewarding, as so few come up with a positive result. Shearer et al (J Med Genet 2013;50:627–34) from Iowa describe their work using recently developed genetic techniques to improve the yield greatly. They recruited 100 patients with non-syndromic hearing loss that clearly did not have an environmental cause, irrespective of family history or previous investigation. Their DNA was then examined using targeted genomic enrichment (TGE) and massive parallel sequencing (MPS) techniques, and the findings analysed using sophisticated bioinformatics. A large and heterogeneous panel of variants were identified that appeared to be associated with hearing loss. They found a positive genetic diagnosis in 46% overall, with higher detection rates in those with symmetric hearing loss and with an autosomal recessive inheritance pattern. ‘Next generation’ sequencing technology (which is the same as MPS) is becoming increasingly available. Sequencing whole exomes or whole genomes is still a research tool in the UK, but targeting specific genes (TGE) is now becoming more generally used. Thus genetic screening for newly diagnosed childhood hearing loss should become more worthwhile in the future, and will help with genetic counselling for parents of newborns identified by routine neonatal hearing tests.
Growth in leukaemia survivors
Cranial irradiation as treatment for acute lymphoblastic leukaemia (ALL) was abandoned in the 1980s, partly because its damaging effect on the pituitary and thus growth hormone (GH) secretion led to stunted growth in survivors. Enough time has elapsed since then to enable the final adult of survivors of ‘chemotherapy only’ regimes to be studied. Vandecruys and colleagues from Belgium looked at a group of 67 adult survivors, who had received ALL chemotherapy regimes of differing intensities as children. (J Pediatr 2013;163:268–73). They found a ‘modest but significant’ final height decrement of 0.59 SD score (±0.86; p<0.001). Looking back at heights measured during and after treatment, they found that most height loss was during treatment, with incomplete catch-up afterwards. Boys lost more than girls. There was no association with intensity of treatment. For most, this left them still within the ‘normal’ range for adult height. The authors also looked at GH response on stimulation testing: only 3 out of 67 were severely abnormal (peak GH response <5 ng/mL), and there was no correlation between GH levels and final height. As GH deficiency now no longer appears to be the main cause of growth restriction, they postulate that the cytotoxic drugs may have a lasting inhibitory effect on long bone epiphyses.
Iron and malaria
In tropical countries, iron-deficiency anaemia and malaria are both enormous threats to child health. There was considerable concern therefore when a study from Zanzibar published in 2006 suggested that iron-supplementation might increase mortality from malaria in children, leading to a caution from the WHO.1 An explanation might be that too much freely available iron in the plasma stimulates parasite reproduction. Recently Zlotkin and colleagues, working in Ghana, completed a study that should reassure us that iron can be given safely in malaria endemic areas (JAMA 2013;310:938–47). In a double-blind, placebo-controlled, nested randomised trial, they used a micro-nutrient powder (MNP), which had been shown in previous studies to be effective in preventing iron-deficiency: nearly 2000 children aged 6–35 months were randomised to receive MNP either with or without iron, over a 6 month period coinciding with the high malaria-risk rainy season. They found no difference between the groups for the primary outcome of episodes of malaria (fever plus proven parasitaemia). Although it wasn't the purpose of the study, as expected they found less anaemia in the iron-supplemented group. They suggest that one explanation for their negative finding compared to the 2006 study was that all the Ghanaian subjects were provided with insecticide-impregnated mosquito nets, and surveillance and treatment for malaria. Also, the administration of iron contained in MNP ‘sprinkles’ given with food may reduce peak plasma iron concentrations. The WHO has very recently updated its advice to reflect these findings.
Can music soothe pain?
Should we play soothing music when subjecting children to painful procedures? Researchers from Edmonton, Canada undertook a randomised controlled trial, studying 42 children aged 3–11 years undergoing intravenous cannula placement, and for half of them played background music (Hartling L et al, JAMA Pediatr online 15 July 2013). They video-recorded their responses to the procedure, and quantified how painful it was perceived to be, using a standardised observational scale of behavioural distress. Cleverly, they blinded the assessors by overdubbing music onto the controls’ recordings. Although overall they found no difference between the groups, when they looked only at those who were distressed to start off with, they found that music had a significant benefit. They also found that the staff were happier with the music group. Perhaps if the staff are more relaxed, the children stay calmer.
Lucina wishes all readers a calm and joyful festive season.