Inactivation of the remaining allele of the WT1 gene in a Wilms' tumour from a WAGR patient.

A candidate gene (WT1) has recently been described for the 11p13 tumour-suppressor gene involved in the development of Wilms' tumour. This gene encodes a zinc finger protein which can bind to a specific DNA sequence. We have found a 226 base deletion in the mRNA from a unilateral Wilms' tumour, which would cause a frameshift that completely deletes the zinc finger domain. The tumour developed in a patient suffering from the WAGR syndrome, who had a constitutional 11p13 deletion, and so the 226 base deletion represents the inactivation of the remaining WT1 allele in the tumour. This provides further direct evidence that loss of function of WT1 is an essential step in the development of Wilms' tumour.

Classification and genetic features of neonatal haemochromatosis: a study of 27 affected pedigrees and molecular analysis of genes implicated in iron metabolism.

Neonatal haemochromatosis (NH) is a severe and newly recognised syndrome of uncertain aetiology, characterised by congenital cirrhosis or fulminant hepatitis and widespread tissue iron deposition. NH occurs in the context of maternal disease including viral infection, as a complication of metabolic disease in the fetus, and sporadically or recurrently, without overt cause, in sibs. Although an underlying genetic basis for NH has been suspected, no test is available for predictive analysis in at risk pregnancies. As a first step towards an understanding of the putative genetic basis for neonatal haemochromatosis, we have conducted a systematic study of the mode of transmission of this disorder in a total of 40 infants born to 27 families. We have moreover carried out a molecular analysis of candidate genes (beta(2)-microglobulin, HFE, and haem oxygenases 1 and 2) implicated in iron metabolism. No pathogenic mutations in these genes were identified that segregate consistently with the disease phenotype in multiplex pedigrees. However, excluding four pedigrees with clear evidence of maternal infection associated with NH, a pedigree showing transmission of maternal antinuclear factor and ribonucleoprotein antibodies to the affected infants, and two families with possible matrilineal inheritance of disease in maternal half sibs, a large subgroup of the affected pedigrees point to the inheritance of an autosomal recessive trait. This included 14 pedigrees with affected and unaffected infants and a single pedigree where all four affected infants were the sole offspring of consanguineous but otherwise healthy parents. We thus report three distinct patterns of disease transmission in neonatal haemochromatosis. In the differentiation of a large subgroup showing transmission of disease in a manner suggesting autosomal recessive inheritance, we also provide the basis for further genome wide studies to define chromosomal determinants of iron storage disease in the newborn.

Postnatal growth preceding sudden infant death syndrome.

OBJECTIVE: To compare postnatal growth preceding the sudden infant death syndrome (SIDS) with that of age matched controls. DESIGN: Retrospective case-control study. Each SIDS victim was matched with two controls on date of parental interview, postnatal age, and neighborhood. Clinical and demographic data were collected by parental interview and by review of medical records, and interval body weights were obtained from health visitors' records. STUDY POPULATION: All infants dying of SIDS between 1 May, 1987 and 30 April, 1989 in a geographically defined region consisting of four health districts in Avon and North Somerset in southwest England. Seventy-eight of the 99 SIDS victims and 139 of 156 control infants were included in the final analysis. RESULTS: There was no significant difference between SIDS victims and the controls in either of the two indices of postnatal growth which were analyzed. The mean growth rates (+/- 1 SEM) between birth and the last live weight (age equivalent weight for control infants) were 27.1 +/- 1.0 g/day for the SIDS cases and 28.3 +/- 1.5 g/day for the control infants. The mean growth rate (+/- 1 SEM) between the last two live weights were 31.5 +/- 2.9 and 24.9 +/- 2.1 g/day for the SIDS and control infants, respectively. Stratification of the infants by sex, gestational age, maternal smoking during pregnancy, breast versus bottle feeding, or age at death, did not result in any significant differences between SIDS and controls in either of the indices of postnatal growth rate. The 20 SIDS cases which were excluded from the final analysis did not differ from 78 whose data was analyzed, with regard to established SIDS risk factors, age at death, or postmortem weight. CONCLUSIONS: No difference was found between the postnatal growth of SIDS victims and that of age matched control infants.

Patterns of ductal tissue in coarctation of the aorta in the first three months of life.

A possible relationship between recurrence of coarctation and the presence of residual ductal tissue in the aorta was studied by defining the presence and pattern of ductal tissue in aortic segments from 23 patients less than 3 months of age who underwent resection of coarctation of the aorta. The surgical policy was to perform extensive excision of the coarctation, including a wide margin of descending aorta beyond the ductus arteriosus. Histologic examination showed that there was a circumferential sling of ductal tissue extending from the ductus arteriosus and surrounding the aorta at the level of the coarctation shelf in 22 specimens. In 15 of these specimens one or two tonguelike prolongations of ductal tissue extended distally from the circumferential sling and occupied constant positions in the aortic wall; one tonguelike prolongation extended distally below the insertion of the ductus and the other from the circumferential sling opposite the ductal insertion. Incomplete excision of ductal tissue was found in 11 specimens. In relation to the goal of avoiding recurrent coarctation after repair in the early months of life, the possible implications of these findings are discussed, and, in particular, a possible mechanism of recurrence after subclavian flap aortoplasty is proposed.

Pathological findings in SIDS.

The original 1969 definition of SIDS as "unexpected by history" and "unexplained after thorough postmortem examination" is under review in the light of two decades of experience. Suggested modifications include restricting the age to less than 1 year, stipulating that the necropsy includes appropriate histology and laboratory tests, and requiring a review of the clinical history and examination of the death scene. The use of a protocol is recommended both by professional and parent groups. Although the diagnosis of SIDS is to some extent one of exclusion, there are several typical findings which are of value in diagnosis and suggest new avenues for research. External examination is important to exclude trauma and signs of suffocation. A recent study has confirmed that petechiae on the face are rare in SIDS and if found raise the question of deliberate or accidental suffocation. Frothy fluid escaping from the nose and mouth is seen in about half of infants who die from SIDS. Postmortem hypostatic staining as an indicator of position has assumed increased importance since prone sleeping has been shown to be a major risk factor for SIDS. Evidence of sweat in clothing suggests overwrapping. Internal examination shows subserosal petechial haemorrhages in the thymus in most cases. These may be related to age and are commoner in babies dying of SIDS than in controls. Relative sparing of the cervical extension of the thymus is strong evidence for negative intrathoracic pressure, perhaps due to upper or lower airway obstruction. Other typical findings are liquid heart blood, prominent lymph nodes, and an empty bladder (which frustrates some biochemical tests in about half of cases). The lungs are usually well inflated, arguing against surfactant deficiency as a significant cause of SIDS. Microscopic evidence of pulmonary oedema and congestion is found in infant deaths for many reasons and is not discriminatory for SIDS. Minor inflammation and infection of the respiratory tract is common in SIDS and may be important by contributing to overheating, apnoea, or sensitisation to bacterial toxins. Mild fatty change in the liver is very common in infant deaths. Panlobular microvesicular fatty change is rare and may require special stains for its recognition. It indicates the necessity of searching for inherited biochemical disorders. Although these are rare in true SIDS, they are an important cause of unexpected death in infancy. Of Naeye's "tissue markers of hypoxia'', extramedullary haemopoiesis in the liver and brainstem gliosis have been confirmed. Persistence of fetal haemoglobin and raised hypoxanthine values in vitreous humour are further pointers to periods of premortem hypoxia. Painstaking neuropathology has shown delayed myelination and maturation of dendritic spines. Changes in the brain may explain the link between antenatal factors such as smoking and SIDS. A second cot death in a family requires expert examination. Minor injuries or unexplained apnoeic spells may be important retrospective clues to non-accidental injury. Investigations mus exclude inherited disorders before the death is ascribed to SIDS. Parents demand that the pathologist takes care of their baby before, during, and after the necropsy, carries out the procedure to a high standard, checks reconstruction of the body, facilitates access, and is responsible for communicating the results of the examination. The "SIDS postmortem" presents both a practical and an intellectual challenge.

Post mortem radiology in children with congenital heart disease.

Contrast radiology has valuable applications in routine necropsy practice. Contrast radiology was used to study the vascular anatomy in four normal fetuses, in five children with cardiovascular malformations, and in two hearts prepared by the perfusion fixation method. A contrast radiograph provides permanent documentation of anatomical associations before they are disrupted by dissection and permits a planned approach to the necropsy. While these injection studies are seldom undertaken by pathologists because they are felt to be too difficult and time-consuming, contrast studies should form part of the post mortem investigation of children with congenital heart disease, even when angiography has been performed in life.

Approaches to the demonstration of congenital heart disease.

Advances in antenatal screening techniques have increased the interest in obtaining a detailed pathological correlation with the ultrasonographic findings obtained before death. As a consequence, inadequacies in traditional methods used by pathologists to display congenital malformations have been brought to light. We describe a simple technique of inflation and wax impregnation for the permanent proof of congenital heart defects that can be used in routine perinatal necropsies.

Postmortem audit in a paediatric cardiology unit.

Postmortem examinations performed on 76 children with a clinical diagnosis of congenital heart disease were reviewed retrospectively and compared with the findings before death. Both operated and unoperated cases were studied over a three year period. Despite intensive investigation during life, there was a high rate of unsuspected abnormalities at necropsy (80%): 29 cases had undiagnosed additional cardiac anomalies or surgical flaws, which contributed to death in 13 cases. Defects in surgery were uncommon but permitted modification in surgical technique to avoid recurrence. Myocardial necrosis and pulmonary foreign body embolism were common findings, the importance of which is uncertain and requires further study for their prevention. Even in the most thoroughly investigated cases postmortem examination has a high yield of clinically important pathology which is undetected during life.

Dicentric chromosome in the bone marrow of a child with megakaryoblastic leukaemia and Down's syndrome.

A two year old girl with Down's syndrome (constitutional karyotype: 47 + 21), presenting with pancytopenia, developed acute megakaryoblastic leukaemia (AMKL). Her bone marrow contained an abnormal clone with a novel dicentric chromosome derived from chromosomes 5 and 7 (karyotype 46, XX, -5, -7, +dic (5;7) (p 13; p 11.2), +21. This case provides further evidence for a connection between chromosome 21 and this unusual form of childhood leukaemia, and raises questions about the loss of short arm material from chromosomes 5 and 7 compared with the more usual monosomy or long arm loss.

Rapid and specific diagnosis of t(11;22) translocation in paediatric Ewing's sarcoma and primitive neuroectodermal tumours using RNA-PCR.

One case of paediatric Ewing's sarcoma and two peripheral primitive neuroectodermal tumours/extra-osseous Ewing's sarcoma were studied for the characteristic t(11;22) translocation, using a recently described RNA-polymerase chain reaction method (RNA-PCR). PCR products of the expected sizes were obtained from RNA derived from the Ewing's sarcoma and the peripheral primitive neuroectodermal tumours, but not from other paediatric malignancies. Direct sequencing of the RNA-PCR products confirmed the presence of the EWS-FLI-1 fusion transcript. In one case the presence of the translocation was confirmed by cytogenetic analysis. These results highlight the potential use of PCR for the rapid demonstration of diagnostically important tumour specific chromosome rearrangements.

Adenovirus and intranuclear inclusions in appendices in intussusception.

AIMS: To examine the light and electron microscopic features of appendices removed at the time of surgical reduction of intussusception in children; and to confirm that the viral inclusions seen in some of them are due to adenovirus. METHODS: A series of 39 appendices from cases of intussusception and 15 control appendices were reviewed. Light microscopic examination of haematoxylin and eosin stained sections was performed on all of them and one appendix with large numbers of inclusions was examined by electron microscopy. Non-isotopic in situ hybridisation using a biotinylated DNA probe was carried out on sections of appendix from 30 of the cases of intussusception and from the 15 controls. RESULTS: Light microscopic examination showed viral inclusions in 19 of the appendices from the cases of intussusception and in none of the controls. Electron microscopic examination showed viral particles with the typical features of adenovirus. Most of the appendices with viral inclusions in the haematoxylin and eosin stained sections also contained adenovirus DNA as shown by in situ hybridisation. CONCLUSIONS: Viral inclusions seen in appendices from cases of intussusception are caused by adenovirus. Adenovirus DNA was not demonstrable in appendices from cases of intussusception without viral inclusions and the aetiological factors involved in intussusception in these children remain unknown.

Congenital malignant rhabdoid tumour of the gum margin.

The case of an infant born with a large polypoid tumour arising from the mouth is described. The tumour had the histological, immunohistochemical and ultrastructural phenotype of an extrarenal malignant rhabdoid tumour and followed an aggressive clinical course. This is one of the few reported cases of malignant rhabdoid tumour to present at birth. The oral tumour was associated with a mass in the posterior cranial fossa. This was most likely to be a simultaneous second primary tumour.

Evaluation of the Oxford and Sheffield SIDS risk prediction scores.

STUDY OBJECTIVE: To evaluate the clinical usefulness (sensitivity and specificity) of the Oxford and Sheffield birth scores for prospective identification of infants at high risk of SIDS. DESIGN: Retrospective medical record reviews of prospectively identified, autopsy-validated SIDS and living control infants. STUDY SUBJECTS: Consecutive sample of 140 infants, born between 1/1/83 and 12/31/87, who died suddenly and unexpectedly in the Avon Area Health Authority in southwest England between 1/1/84 and 12/31/88. Seventeen of the cases were excluded: 6 because they lacked adequate clinical records, 11 because they were not SIDS. The 637 control infants were comprised of every 80th delivery between 1/1/83 and 12/31/87 in the three major hospitals in the area. RESULTS: SIDS incidence was 2.85/1,000 live births. Using standard cut scores to define high SIDS risk (2.0 for Oxford and 500 for Sheffield), sensitivities were 0.55 and 0.35 and specificities were 0.78 and 0.89 for the Oxford and Sheffield scores, respectively. SIDS risk for infants in the high risk group was 7.3/1,000 (Oxford) and 9.3/1,000 (Sheffield). CONCLUSIONS: Since there is no intervention with proven efficacy for SIDS prevention, and since approximately one half of SIDS cases occur in low risk groups, clinical use of these scoring systems for allocation of health care resources or personnel for the sole purpose of SIDS prevention is not justified.

Coexistent cardiac tumours and malformations of the heart.

Cardiac tumours and anatomical malformations of the heart may produce similar clinical signs and symptoms. The coexistence of these two abnormalities complicates diagnosis and probably adversely affects prognosis. We present a review of four cases of this rare combination. In the first case, Ebstein's malformation was present in a child with tuberous sclerosis and cardiac rhabdomyomata. Right ventricular rhabdomyomata were associated with a hypoplastic tricuspid valve in the second case. In the third case, cardiac myxomas were detected in a child with a double-chambered right ventricle. The fourth case was a child with a fibroma of the right ventricle with pulmonary atresia. We propose that, in some circumstances, a space-occupying lesion may be associated with, or possibly induce, a malformation within the developing heart.

Parvovirus infection of the human fetus and newborn.

Human parvovirus B19 is a recently recognized cause of hydrops fetalis. It is a small, single-stranded DNA virus, which preferentially infects late erythroid precursors and produces red blood cell (RBC) aplasia, fetal anemia, and cardiac failure. Infection is accompanied by characteristic intranuclear inclusions in fixed and circulating RBC precursors. These inclusions have been shown to contain virus particles by electron microscopy and in situ hybridization. Infection of the fetus, mother, and newborn infant can be diagnosed by serological and molecular methods selected to match the stage of the infection. Recent work has shown that parvovirus B19 can infect cells other than erythroid precursors, and that additional mechanisms such as myocarditis may contribute to hydrops fetalis in some cases. Infected fetuses are not always hydropic. Maternal infection results in increased abortion and stillbirth even in the absence of transplacental transmission, which occurs in approximately one third of infected mothers. The overall risk of fetal loss following maternal exposure is much less than previously thought, and may be less than 3% in the first 20 weeks of gestation or approximately 10% if the mother is actually infected. Although parvoviruses are teratogenic in animals, there is no evidence that B19 is a significant teratogen in man. The long-term outlook of survivors of intrauterine infection, including those successfully treated by intrauterine blood transfusion, appears to be good, but requires further study.

The immunocytochemical demonstration of a relative lack of nerve fibres in the atrioventricular node and bundle of His in the sudden infant death syndrome (SIDS).

Whilst examining the variation with age of the nerve fibre content of the cardiac conduction system (CCS), using an immunocytochemical approach, it became evident that in two sudden infant death syndrome (SIDS) cases there was a selective lack of S100 positive nerve fibres in the atrioventricular (AV) node and His bundle. In the present study therefore, the examination of CCS with S100 was extended to a further five SIDS cases and three cases of sudden explained death. Also, in addition to S100--which selectively marks Schwann cells associated with both myelinated and non-myelinated nerves--PGP 9.5 (protein gene product) was used to reveal the presence of nerve axonal elements associated with the CCS. The results showed a uniform presence of S100 and PGP 9.5 positive nerve fibres in the sinoatrial (SA) node, the AV node and His bundle tissue of all three control cases. In contrast, five out of seven SIDS cases showed a uniform lack of staining with these markers in the AV node and His bundle tissue, whilst in the two remaining cases it was present in greatly diminished amounts. Staining in the SA node, although present in all seven cases, was reduced when compared with the control cases. This is the first time the CCS of SIDS cases has been studied with immunocytochemical markers of nerve elements. The overall results taken in conjunction with the epidemiology of SIDS suggest that the lack of AV node and His bundle innervation most probably reflects a delay in the development or maturation of the nerve elements of the CCS, similar to that noted for other parts of the central and peripheral nervous systems in SIDS.

Can the fall in Avon's sudden infant death rate be explained by changes in sleeping position?

OBJECTIVE: To examine the impact of changing practice with regard to infant sleeping position on mortality from the sudden infant death syndrome. DESIGN: A population based study of all infants dying suddenly and unexpectedly during February 1990 to July 1991, and two groups of controls; one comprising every 125th baby born to Avon residents and the other comprising pairs of infants matched to each index case for age, neighbourhood, and date of study. Information about sleeping position was collected at home visits soon after the index baby's death or, for the population based controls, on several occasions in the first six months of life. The design was comparable to that of an earlier study of the same population. SETTING: County of Avon. SUBJECTS: 35 infants who died suddenly and unexpectedly (32 of the sudden infant death syndrome), 70 matched controls, and 152 population based controls. RESULTS: The prevalence of prone sleeping in the matched controls was much lower than that found in an earlier study in Avon (28% (18/64) 1990-1 v 58% (76/131) 1987-9; p less than 0.001) and was comparable with the prevalence in population based controls (29%). This would be expected to lead to a reduction in the incidence of the sudden infant death syndrome to 2.0/1000 live births (95% confidence interval 1.8/1000 to 2.5/1000). The actual mortality fell from 3.5/1000 in 1987-9 to 1.7/1000. CONCLUSION: The fall in mortality can be almost entirely accounted for by the reduction in prone sleeping, suggesting a causal relation exists between them. Side and supine positions confer protection but the side position is unstable and the infant may roll prone. We therefore recommend supine as the safest sleeping position for babies.

Bottle feeding and the sudden infant death syndrome.

OBJECTIVE: To determine whether the risk of the sudden infant death syndrome is increased in bottle fed babies. DESIGN: Population based case-control study matching for age and time. SUBJECTS: All babies aged 1 week to 1 year dying of sudden infant death syndrome during November 1987 to April 1989 or February 1990 to June 1991 and two live controls. SETTING: Avon and north Somerset. MAIN OUTCOME MEASURES: Breast or bottle feeding, sleeping position, maternal smoking, parental employment, and length of gestation. RESULTS: Compared with being fully breast fed, the crude odds ratio for sudden infant death in fully bottle fed babies was 3.1 and for mixed breast and bottle fed babies 1.5. These odds ratios fell to 1.8 (95% confidence interval 0.7 to 4.8) and 1.2 (0.5 to 2.7) respectively after maternal smoking, parental employment, preterm gestation, and sleeping position had been adjusted for. Sleeping position partly masked the effect of being bottle fed on sudden infant death as breast fed babies were more likely to have slept prone than bottle fed babies. CONCLUSIONS: Bottle feeding is not a significant independent risk factor for the sudden infant death syndrome. Patterns of maternal smoking, preterm gestation, and parental employment status account for most of the apparent association with bottle feeding.

Interaction between bedding and sleeping position in the sudden infant death syndrome: a population based case-control study.

OBJECTIVE: To determine the relation between sleeping position and quantity of bedding and the risk of sudden unexpected infant death. DESIGN: A study of all infants dying suddenly and unexpectedly and of two controls matched for age and date with each index case. The parents of control infants were interviewed within 72 hours of the index infant's death. Information was collected on bedding, sleeping position, heating, and recent signs of illness for index and control infants. SETTING: A defined geographical area comprising most of the county of Avon and part of Somerset. SUBJECTS: 72 Infants who had died suddenly and unexpectedly (of whom 67 had died from the sudden infant death syndrome) and 144 control infants. RESULTS: Compared with the control infants the infants who had died from the sudden infant death syndrome were more likely to have been sleeping prone (relative risk 8.8; 95% confidence interval 7.0 to 11.0; p less than 0.001), to have been more heavily wrapped (relative risk 1.14 per tog above 8 tog; 1.03 to 1.28; p less than 0.05), and to have had the heating on all night (relative risk 2.7; 1.4 to 5.2; p less than 0.01). These differences were less pronounced in the younger infants (less than 70 days) than the older ones. The risk of sudden unexpected death among infants older than 70 days, nursed prone, and with clothing and bedding of total thermal resistance greater than 10 tog was increased by factors of 15.1 (2.6 to 89.6) and 25.2 (3.7 to 169.0) respectively compared with the risk in infants of the same age nursed supine or on their side and under less than 6 tog of bedding. CONCLUSIONS: Overheating and the prone position are independently associated with an increased risk of sudden unexpected infant death, particularly in infants aged more than 70 days. Educating parents about appropriate thermal care and sleeping position of infants may help to reduce the incidence of the sudden infant death syndrome.