Allan G. Howatson

Identification of novel polymorphisms in the glucokinase and glucose-6-phosphatase genes in infants who died suddenly and unexpectedly

Sudden and unexpected infant deaths can be unexplained [sudden infant death syndrome (SIDS)] or explained (non-SIDS) but risk factors including lower birthweight are similar in both groups. Mutations in the glucokinase (GK) gene result in Maturity Onset Diabetes of the Young type 2 (MODY 2) and are associated with lower birthweight. Low hepatic glucose-6-phosphatase (G6PC1) expression occurs in both low birthweight and SIDS infants. We investigated whether polymorphisms are prevalent in the GK and G6PC1 genes in infants who died suddenly and unexpectedly. Mutation analysis was performed by polymerase chain reaction (PCR) and denaturing high-performance liquid chromatography (DHPLC) in samples from 126 infants who died suddenly and unexpectedly (78 SIDS, 48 non-SIDS) and from 70 healthy, living infants. G6PC1 promoter polymorphism significance was investigated by transfection of reporter gene constructs into a H4IIE cell line. Heterozygous GK polymorphisms were identified in 17.9% of SIDS and 20.8% of non-SIDS infants: two rare silent polymorphisms, Y215Y and S263S, in the coding region; a third rare polymorphism, −45G>A, in the hepatic promoter and the most prevalent polymorphism, c.484–29G>C, in a non-coding region upstream from the intron 4–exon 5 junction. A novel heterozygous polymorphism −77G>A in the G6PC1 promoter in 6.3% of non-SIDS and 2.9% of control infants decreased basal G6PC1 promoter activity (p<0.001). We describe three novel polymorphisms in the GK gene, S263S, −45G>A, and a common (14.3%) intronic substitution, c.484–29G>C, in infants who died suddenly and unexpectedly. We identified the first G6PC1 promoter polymorphism, which lowers expression, potentially increasing risk of hypoglycaemia and hence risk of sudden and unexpected death.

Age dependence of potentially toxic elements (Sb, Cd, Pb, Ag) in human liver tissue from paediatric subjects

Toxic elements are present at low concentrations in the environment. This work was undertaken to investigate the age dependence of the liver content of selected elements in paediatric populations, as an index of internal exposure. Liver samples were collected at autopsy from 157 subjects, aged < 1 day to 6 years, as part of investigations on a possible role of Sb compounds in sudden infant death syndrome (SIDS). In addition to Sb, the concentrations of Ag, Cd and Pb were also determined by inductively coupled plasma mass spectrometry on the remaining digest. Comparison of 95% confidence intervals of the median concentrations of the four elements suggested that there were no differences between the two categories of cause of death, SIDS or those who had died of an identified disease. Cadmium, lead and antimony median concentrations were lower than corresponding values observed in adult populations. Silver concentrations were significantly higher at birth and decreased with age. Cadmium levels were almost negligible in neonates and infants, but increased in older children. The finding of non-negligible concentrations of both Ag and Pb in neonatal liver provides further direct evidence that these elements cross the human placental barrier. The reported data, by far the largest collection observed in subjects less than 1 year old, are the result of exposure, during pregnancy and in early childhood, to present levels of these elements in the environment. They can serve as a reference to compare post-mortem values from individuals or groups of subjects in this age range when an exposure risk is suspected and to highlight trends in human exposure.

Renal transplant biopsy specimen adequacy in a paediatric population

Updated guidelines on the diagnosis of acute allograft rejection including criteria for biopsy specimen adequacy were published in 1999. We sought to determine the adequacy of specimens in paediatric transplant patients and identify factors influencing adequacy. All renal transplant biopsies performed between 1998 and 2003 were classified as adequate (n =25), minimal (n =19) or inadequate (n =27) in accordance with the Banff 97 criteria, and the histological diagnoses were documented. The effect on specimen adequacy of grade of operator, method of sedation, age of child, needle gauge, number of cores and total core length was then investigated. Overall, a minimal or adequate specimen was obtained in 62% of cases. No histological diagnosis could be made in 30% of all specimens, just over half of which were inadequate. Higher rates of rejection were found in adequate (52%) than inadequate (33%) samples. The grade of operator (p =0.498), the age of the child at the time of biopsy (p =0.815) and type of sedation (p =0.188) did not affect adequacy. More than one core was obtained in 38 (54%) cases, and this was significantly associated with specimen adequacy (p <0.0005) as was longer total core length (p =0.002). Clinical features in isolation are not sufficient for the diagnosis of acute allograft rejection. Renal biopsy remains the gold standard and relies on adequate specimen collection. Our data shows that specimen adequacy according to the Banff 97 guidelines is achievable in children and that more than one core at the time of sampling significantly improves this achievement. Adequate sampling reduces the risk of an inconclusive histological diagnosis.

Unadjusted and customised weight centiles in the identification of growth restriction among stillborn infants

The study aims to compare the utility of unadjusted with customised weight standards in the identification of intrauterine growth restriction (IUGR) among unexplained stillborn infants undergoing postmortem examination. Unadjusted and customised birthweight centiles were determined for 51 unexplained stillborn infants undergoing perinatal autopsy. Unadjusted centiles were calculated from an ultrasonically derived fetal weight standard. Customised centiles were calculated from an online calculator which adjusts the standard to account for important physiological variables. IUGR was defined as moderate or severe according to brain/liver ratios of >3 and >5, respectively. The relationship between the weight centiles and abnormal brain/liver weight ratios was explored. Neither unadjusted nor customised standards identify stillborn infants with brain/liver ratios >3:1. Both unadjusted and customised weight standards identify stillborn infants with brain/liver ratios >5 equally well with high sensitivity (95%) but low specificities (63% and 66%, respectively). Customising weight standards to account for physiological variables does not identify growth restricted stillborn infants more usefully than an unadjusted fetal weight standard.

The pathology of visible blood vessels on the nasal septum in children with epistaxis.

OBJECTIVE Epistaxis is common in children, but its cause remains unknown. About half the children who present with epistaxis have prominent vessels on the nasal septum. The aim of this study was to determine the pathological nature of the prominent septal vessels in children with recurrent epistaxis. METHODS 4mm punch biopsies of the nasal septal mucosa were taken from 5 children undergoing nasal cautery under general anaesthesia. RESULTS Histology showed that the prominent vessels were thin-walled arterioles and capillaries with a surrounding inflammatory infiltrate. There was no evidence of venous varicosities or arterial microaneurysms. CONCLUSION We postulate a mechanism for septal neovascularisation due to chronic low-grade inflammation as a cause for recurrent epistaxis in children.

Genetic variation in hepatic glucose-6-phosphatase system genes in cases of sudden infant death syndrome.

Genetic deficiencies of the hepatic glucose‐6‐phosphatase system, either of the enzyme (G6PC1) or of the glucose‐6‐phosphate transporter (G6PT1), result in fasting hypoglycaemia. Low hepatic G6PC1 activities were previously reported in a few term sudden infant death syndrome (SIDS) infants and assumed to be due to G6PC1 genetic deficiencies. In preterm infants, failures of postnatal activation of G6PC1 expression suggest disordered development as a novel cause of decreased G6PC1 activity in SIDS. G6PC1 and G6PT1 functional and mutational analysis was investigated in SIDS and non‐SIDS infants. G6PC1 hepatic activity was abnormally low in 98 SIDS (preterm, n = 13; term, n = 85), and non‐SIDS preterm infants (n = 35) compared to term non‐SIDS infants (n = 29) and adults (n = 9). Mean glycogen levels were elevated, except in term non‐SIDS infants. A novel G6PT1 promoter polymorphism, 259C → T was found; the − 259*T allele frequency was greater in term SIDS infants (n = 140) than in term control infants (n = 119) and preterm SIDS infants (n = 30). Heterozygous and homozygous prevalence of 259C → T was 38.6% and 7.1%, respectively, in term SIDS infants. In cell‐based expression systems, the presence of − 259T in the promoter decreased basal luciferase activity by 3.2‐fold compared to − 259C. Glucose‐6‐phosphatase latency in hepatic microsomes was elevated (indicating decreased G6PT1 function) in heterozygous and homozygous − 259T states. Delayed postnatal appearance of hepatic glucose‐6‐phosphatase in infants makes them vulnerable to hypoglycaemic episodes and this may occur in some SIDS infants. However, SIDS may be an association of more complex phenotypes in which several genes interact with multiple environmental factors. A UK‐wide DNA Biobank of samples from all infant deaths, with an accompanying epidemiological database, should be established by pathologists to allow cumulative data to be collected from multiple genetic investigations on the same large cohort of samples, with the aim of selection of the best combination of genetic markers to predict unexpected infant death. Copyright

Determination of low concentrations of potentially toxic elements in human liver from newborns and infants

One hundred and fifty-seven liver samples from newborns and infants who had died from sudden infant death syndrome (SIDS) or other known causes have been analysed by ICP-MS for Ag, Cd, Co, Pb and Sb. The median concentrations found were: 15.4 (Ag), 2.9 (Cd), 15.9 (Co), 65.2 (Pb) and 1.8 (Sb) ng g-1 wet mass. There was no measurable difference in the concentrations of any of these elements between the SIDS and non-SIDS groups. The validity of the results was assessed by analysis of appropriate reference materials, interlaboratory comparison and isotope dilution analysis. The instrumental limits of detection were 0.25 (Ag), 0.14 (Cd), 0.21 (Co), 3.8 (Pb) and 0.38 (Sb) ng g-1 wet mass. The limits of detection of the method depend on the reagent blank and the extent of background contamination.

Focal segmental glomerulosclerosis, Coats'-like retinopathy, sensorineural deafness and chromosome 4 duplication: a new association.

We describe the novel association in a girl of nephrotic syndrome due to focal segmental glomerulosclerosis, bilateral sensorineural deafness, basal ganglia calcification, bilateral retinopathy similar to that seen in Coats’ disease, with de novo duplication of a subtelomeric region of chromosome 4q35. The chromosomal duplication was identified during investigation of a possible association with features of fascio-scapulo-humeral dystrophy (FSHD). This duplication has not previously been reported with FSGS and adds to the expanding number of genetic associations with steroid-resistant nephrotic syndrome.

Reversible chronic pulmonary fibrosis associated with MMF in a pediatric patient: a case report.

Abstract:  We describe a case of chronic mineralizing pulmonary elastosis in a seven‐yr‐old boy following DD renal transplantion for Wilms tumour. Fourteen months post‐transplantion he developed respiratory symptoms with lung biopsy demonstrating chronic mineralizing pulmonary elastosis thought to be secondary to immunosuppression with MMF. Symptomatic resolution occurred following MMF cessation.

Retraction Note to: Multifocal multi-organ ischaemia and infarction in a preterm baby due to maternal intravenous cocaine use: a case report

Introduction Although the adverse effects of cocaine use in pregnancy are well recognised, we believe this case highlights the importance of considering the route of administration, and suggests the possibility of multifocal damage relating to intravenous use.