WITHDRAWN: NaS1 sulfate transporter is linked to hyposulfatemia and longevity.

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Analysis of N- and O-linked protein glycosylation in children with Prader-Willi syndrome.

BACKGROUND: Current genotype-phenotype correlations in Prader-Willi syndrome (PWS) are struggling to give an explanation of the diversity in phenotype and there is a need to move towards a molecular understanding of PWS. A range of functions related to glycoproteins are involved in the pathophysiology of PWS and it may be that abnormal glycosylation is contributing to the biological phenotype. The objective of this study was to investigate the state of N- and O-linked glycosylation in children with Prader-Willi syndrome. METHODS: Twenty-three children with PWS and 20 non-PWS controls were included in the study. Protein N-linked glycosylation was assessed by analysing serum transferrin through mass spectrometry and protein O-linked through isoelectric focusing (IEF) of serum apolipoprotein C-III (apoC-III), confirmed by mass spectrometry. RESULTS: The results of this analysis indicated that the N-linked glycosylation pathway in PWS is normal. A subgroup of PWS individuals was found to have a hyposialylated pattern of apoC-III isoforms. This was independent of the underlying genetic mechanism and is the first report of an apoC-III IEF abnormality in PWS. CONCLUSIONS: This is the first report of apoC-III hyposialylation in PWS. As this field is in its infancy, additional study is required before these findings may be used in clinical settings.

21-hydroxylase genotyping in Australasian patients with congenital adrenal hyperplasia.

Mutations in CYP21 (21-hydroxylase) lead to congenital adrenal hyperplasia (CAH). We genotyped 26 probands with CAH by PCR-sequencing the entire CYP21 gene. 25/26 had homozygous or compound heterozygous mutations. The frequencies of mutations were similar to other populations with deletion/hybrid, I2 G splice and I172N the most common. Five patients with a I172N allele predicting simple-virilising CAH had a salt-wasting phenotype. Two other probands also had a more severe phenotype than predicted by genotype. Two families had both non-classic and salt-wasting phenotypes arising from combinations of three deleterious alleles. Two novel CYP21 alleles were detected: D106N and a large deletion encompassing CYP21 and adjacent pseudogene. Two rare CYP21 alleles were also found. Three of these four novel/rare alleles were only detected as a result of sequencing the entire CYP21 gene. Entire CYP21 sequencing will increase the number of mutations detected in CAH, and in combination with functional studies should contribute a greater understanding of phenotype-genotype correlations.

Seizures, ataxia, developmental delay and the general paediatrician: glucose transporter 1 deficiency syndrome.

AIM: Glucose transporter 1 deficiency syndrome (GLUT1-DS) is an important condition for the general paediatrician's differential armamentarium. We describe a case series of eight patients in order to raise awareness of this treatable neurometabolic condition. The diagnosis of GLUT1-DS is suggested by a decreased absolute cerebrospinal fluid (CSF) glucose value (<2.2 mmol/L) or lowered CSF: plasma glucose ratio (<0.4). METHODS: This is a review of eight Queensland patients with GLUT1-DS. The clinical presentation, clinical course, laboratory investigations and treatment outcomes are discussed. RESULTS: The clinical features noted in our patient cohort include combinations of ataxia, developmental delay and a severe seizure disorder that is refractory to anticonvulsant medications. Seizures are the most common clinical manifestation and may be exacerbated by phenobarbitone. The paired CSF: plasma glucose results ranged from 0.2 to 0.39 (normal <0.6) with an average of 0.33. 3-O-Methyl-D-Glucose uptake and GLUT1 Genotyping analysis have been performed on five patients thus far. Rapid and impressive seizure control was observed in 100% of our patients once the ketogenic diet was instituted, with half of the cohort being able to wean completely from anticonvulsants. CONCLUSION: Children presenting with a clinical phenotype consisting of a refractory seizure disorder, ataxia and developmental delay should prompt the consideration of Glucose transporter 1 deficiency syndrome. While the diagnostic test of lumbar puncture is an invasive manoeuvre, the diagnosis provides a viable treatment option, the ketogenic diet. GLUT1-DS displays clinical heterogeneity, but the value of early diagnosis and treatment is demonstrated by our patient cohort.

Alcoholic liver disease: a clinical series in an Australian private practice.

BACKGROUND AND AIM: The published literature on alcoholic liver disease (ALD) in Australia lacks a large clinical series out of private practice as distinct from hospital-based hepatology referral units. This series describes the presentation and clinical features of ALD in a consecutive series out of metropolitan private practice in Australia. METHODS: A retrospective descriptive study by case-note review found 297 cases of ALD at a Brisbane practice over 20 years. The main outcome measures were: clinical features and stage at presentation, reasons for referral, and the predictive value of aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio. RESULTS: Most patients (57.9%) had no symptoms of liver disease and 29 patients (9.8%) had neither symptoms nor signs. Cirrhosis was found in 41% of patients and hepatitis-fibrosis was found in 26% of patients. The male to female (M : F) ratio was 4.7:1. The AST/ALT ratio was not reliably predictive of ALD stage. The average reported daily alcohol intake was 131 g. Females drank less on average and presented a more vigorous clinical picture. CONCLUSIONS: This series presents the spectrum of ALD in a metropolitan Australian private practice. Many patients are asymptomatic on presentation. All heavy drinkers should be targeted for early investigation without waiting for volunteered symptoms or abnormal physical signs. The male to female ratio in ALD is higher than hitherto reported. The AST/ALT ratio is not generally applicable in the staging of ALD. The differences from hospital series data suggest the demography and epidemiology of ALD in Australia are incomplete, and further study is warranted.

Carbohydrate-deficient glycoprotein syndrome in a newborn with an unbalanced chromosomal translocation.

UNLABELLED: Carbohydrate-deficient glycoprotein syndromes may occur as a primary result of distinct genetic disruption of the enzymes involved in processing the carbohydrate moeities of glycoproteins. They may also occur due to a number of secondary defects in glycosylation. CONCLUSION: A female infant with an unbalanced chromosomal translocation [46,XX,der(21)t(17;21) (p13.1;q22.11)mat.ish der(21)t(17;21) (D17S375 x 3, D21S65-)] and with biochemical and clinical features of a carbohydrate deficient glycoprotein syndrome is reported. This chromosomal disruption is another secondary cause of the disorder.

Evaluating photoscreeners II: MTI and fortune videorefractor.

BACKGROUND: Amblyopia is a public health problem, usually amenable to treatment if detected early. Photoscreeners are camera-based instruments which can detect risk factors for amblyopia such as squint, refractive errors and media opacities. OBJECTIVE: To evaluate two commercially available photoscreeners, namely the MTI photoscreener (Medical Technology, Iowa City, IA, USA) and the Fortune Optical VRB-100 (Fortune Optical, Padova, Italy) videophotorefractor, in a selected childhood population, having a high prevalence of amblyopia, before undertaking a full-scale trial in the general population. SUBJECTS AND METHODS: The study design was a double-masked study. One-hundred and five children aged between 12 and 44 months with either normal vision or known visual disorders were photoscreened without cycloplegia using the Fortune and the MTI photoscreeners. Each child had a full ophthalmic examination either on the day of screening or in the preceding 6 months. Risk factors were: any manifest strabismus (squint), hypermetropia >3.5 D, anisometropia > or =1 D sphere, myopia > or =2 D sphere, astigmatism > or =2 D, media opacity or fundus abnormality affecting vision. The prevalence of risk factors for amblyopia was 60%. Photoscreen images were reviewed by two independent masked observers for indicators of amblyopiogenic risk factors and compared to the full ophthalmological examination to determine sensitivity and specificity for each instrument. RESULTS: Sensitivities and specificities for the detection of risk factors for amblyopia were as follows. Fortune photoscreener: reader 1, sensitivity 60%, specificity 75%; reader 2, sensitivity 68% specificity 86%. MTI photoscreener: reader 1, sensitivity 56%, specificity 79%; reader 2, sensitivity 61%, sensitivity 86%. The results for reader 1 and 2 showed no significant differences for either instrument. CONCLUSION: Both instruments performed unsatisfactorily in a study population aged 1-4 years with a high prevalence of amblyopiogenic risk factors. Accordingly, we do not believe that either instrument can be recommended to screen for eye disorders in children between the ages of 1 and 4 years because the low prevalence of amblyopia in this population demands very high sensitivity and specificity in order to avoid inappropriate over- or under-referral.

Evaluation of photoscreener instruments in a childhood population. 1. Otago photoscreener and Dortmans videophotorefractor.

OBJECTIVE: To evaluate two photoscreeners in a childhood population. STUDY DESIGN: Double-masked study. SUBJECTS AND METHOD: One hundred and thirteen children aged between 11 and 44 months with either normal vision or known visual disorders were photoscreened without cycloplegia by the Otago and Dortmans (prototype) photoscreeners. Each child had a full ophthalmological examination either on the day of screening or in the proceeding six months. Photoscreen images were reviewed by an independent observer for indicators of amblyopiogenic risk factors, and compared to the full ophthalmological examination to determine sensitivity and specificity for each instrument. RESULTS: The Otago photoscreener returned a sensitivity of 70% and specificity of 82% for the detection of amblyopiogenic risk factors. The Dortmans photoscreener returned a sensitivity of 70% and specificity of 90%. Both photoscreeners were portable and easily operated. CONCLUSION: Children can be screened successfully for amblyopiogenic risk factors with these photoscreening systems. Further evaluation is required to determine specificity in a normal population. This would also provide information on the potential usefulness of photoscreeners in a cost effective childhood vision screening program.

Evaluation of growth and changes in body composition following neonatal diagnosis of cystic fibrosis.

Early deficits in nutritional status that might require specific treatment and early response to nutritional therapy were studied longitudinally in 25 infants with cystic fibrosis (CF) diagnosed by neonatal screening, using anthropometric and research body composition methodology, and evaluation of pancreatic function. At the time of confirmed diagnosis (mean 5.4 weeks), body mass, length, total body fat (TBF), and total body potassium (TBK) were all significantly reduced. Following diagnosis and commencement of therapy there was a normalization of weight, length, and TBK by 6-12 months of age, indicating catch-up growth. But in some individuals the response was incomplete, and as a group, mean total body fat remained significantly lower than normal at 1 year of age. Seven of 25 (28%) were pancreatic sufficient at diagnosis, and all but one had evidence of declining pancreatic function requiring the institution of pancreatic enzyme therapy during the next 1-9 months. The median age of commencement of enzyme therapy was 10 weeks (range 5 weeks to 11 months). These longitudinal assessments emphasize the dynamic changes occurring in absorptive function, body composition, and nutritional status following neonatal diagnosis of cystic fibrosis and may reflect previously described abnormalities of energy metabolism in this age group. Abnormal body composition is evident in most CF infants following diagnosis by neonatal screening but pancreatic damage may still be evolving. We suggest that early active nutritional therapy and surveillance for changes in pancreatic function are warranted in CF infants diagnosed by neonatal screening.

Carnitine in dried blood spots: a method suitable for neonatal screening.

A method is described which enables the quantitative determination of both free and total carnitine levels in dried blood spots. This method is suitable for neonatal screening for either primary or secondary carnitine deficiency. The 95% confidence interval for free carnitine was 26-76 mumol/l (median = 44) and for total carnitine was 35-102 mumol/l (median = 60).

Exocrine pancreatic dysfunction in malnourished Australian aboriginal children.

Pancreatic exocrine dysfunction has been frequently recorded in protein-energy malnutrition in underdeveloped countries. In addition, the pancreas requires optimal nutrition for enzyme synthesis and potentially correctable pancreatic enzyme insufficiency may play a role in the continuation of protein-energy malnutrition. This problem has not been previously evaluated in Australian Aborigines. We have applied a screening test for pancreatic dysfunction (human immunoreactive trypsinogen [IRT] assay) to the study of 398 infants (6-36 months) admitted to the Alice Springs Hospital over a 20-month period. All infants were assessed by anthropometric measures and were assigned to three nutritional groups (normal, moderate or severely malnourished) and two growth groups (stunted or not stunted). Of the 198 infants who had at least a single serum cationic trypsinogen measurement taken, normal values for serum IRT (with confidence limits) were obtained from 57 children, who were normally nourished. IRT levels were significantly correlated with the degree of underweight but there was no correlation with the degree of stunting or age. Mean IRT levels for the moderate and severely underweight groups were significantly greater than the mean for the normal group (P less than 0.01). Seventeen children (8.6%) had trypsinogen levels in excess of the 95th percentile for the normally nourished group, reflecting acinar cell damage or ductal obstruction. We conclude that pancreatic dysfunction may be a common and important overlooked factor contributing to ongoing malnutrition and disease in malnourished Australian Aboriginal children.

Neonatal screening and an intensive management programme for galactosaemia: early evidence of benefits.

A prospective study of children with galactosaemia is being undertaken at the Metabolic Clinic, Royal Children's Hospital, Brisbane. The purpose of the study is to collect biochemical, clinical, dietary, developmental and speech and language data. This paper describes the operation of the multiprofessional management programme and reports results for two groups of children: those who were diagnosed before the introduction of neonatal screening in 1982 (the prescreening group) and those who were identified by screening. The eight children in the prescreening group have shown intellectual development in the low-average to moderately-handicapped range. Most of them have speech and language difficulties. The screening group, all of whom are still in infancy or early childhood, appears to be developing normally, with the exception of one child who is showing problems with speech and language. The early results provide a basis for cautious optimism that neonatal screening and careful management will result in improved outcomes for children with galactosaemia.

Newborn screening for cystic fibrosis using an enzyme linked immunoabsorbent assay (ELISA) technique.

Neonatal screening for cystic fibrosis (CF) has been conducted using conventional radioimmunoassay. An alternative immunoassay approach has been developed and applied to screening 35,550 newborns. Seventeen confirmed CF infants were detected by both assays. This monoclonal antibody-based enzyme immunoassay using microtitre plate ELISA technology has proved effective in case finding and offers a number of advantages. A reduced labour component, ease of handling, use of nonradioactive reagents, long reagent shelf-life, greater specificity and a reduction in potential sample handling and transposition errors combine to make this technology appropriate for a large volume neonatal screening laboratory.

Monoclonal antibody-based enzyme immunoassay for trypsinogen in neonatal screening for cystic fibrosis.

An enzyme immunoassay (EIA) with monoclonal antibodies against human trypsinogen in neonatal blood-spots has been evaluated for screening for neonatal cystic fibrosis (CF). In a retrospective study, 36 of 39 CF samples were distinguished from controls matched for age and storage time. 7 infants with CF were detected in 16,500 infants screened in a prospective study. The EIA is quicker and less labour intensive than conventional assays for the detection of immunoreactive trypsin and may have further advantages of specificity and sensitivity for monitoring the release of pancreatic zymogens in CF.

A case of uridine diphosphate galactose-4-epimerase deficiency detected by neonatal screening for galactosaemia.

An infant with a deficiency of the enzyme uridine diphosphate galactose-4-epimerase was detected during galactosaemia screening of the Queensland newborn population. No case of epimerase deficiency has been reported previously in Australia and the incidence in our population is unknown. A deficiency of this enzyme is usually quite benign although two cases with a galactosaemia-like syndrome have been reported. This infant is developing normally, both intellectually and physically, in spite of extremely high levels of red blood cell galactose-1-phosphate. The introduction of newer methods of galactosaemia screening in Australia will probably result in the detection of other cases of this enzyme deficiency.

Development of a protocol for newborn screening for disorders of the galactose metabolic pathway.

The protocol evaluated in this paper employs an enzymatic assay of galactose metabolites, thin layer chromatography, and an assay of galactose-1-phosphate uridyl transferase on a single sample of blood collected routinely for newborn screening. Its effectiveness was tested by a retrospective study of known galactosemic blood samples, and also by a prospective study of 207,000 newborn samples from which 6 infants with severe transferase deficient galactosaemia and 2 infants with red cell epimerase deficiency were identified. The detection rate for severe transferase deficiency in the newborn population was 1:35,000. Advantages include low false positive rate, definitive diagnosis within 6 hours of sample receipt, and the use of technically simple and robust procedures. This protocol overcomes the difficulties encountered with previously described procedures.

Factors influencing referrals for prenatal cytogenetic diagnosis.

This paper reports the results of an investigation into factors influencing the referral of women for prenatal cytogenetic diagnosis, following mid-second-trimester amniocentesis. The overall diagnostic amniocentesis rate for women over the age of 35 years was 16.8%. One hundred and forty consecutive Brisbane women referred to the 2 Queensland laboratories offering chromosome analysis of amniotic fluid cells were included in this study. 72% were referred for advanced maternal age. The socioeconomic status (SES) of the 140 women was skewed very significantly towards the professional and semiprofessional classes (Classes A and B on the Congalton Australian Four-point Scale). Twenty seven percent of all women are in SES Class D in the Brisbane population, but only 7.4% of such women (SES Class D) were within the group studied. Forty nine percent of women indicated that they themselves raised the question of prenatal diagnosis with their doctor. Diagnostic amniocentesis is not acceptable to a certain proportion of couples, but it is estimated that 60% would accept it if there were medical indications, and if it were offered. Our studies have indicated that of those women who are at increased risk of having a child with a significant chromosomal abnormality (including those over the age of 35 years) and to whom prenatal diagnosis is acceptable, 28% are actually receiving it in current practice. Those who do are a well informed, self-motivated upper and middle class group.

Register of chromosomal abnormalities in Queensland.

The development and use of the computer-aided retrieval of karyotypes (CAROK), a register of chromosomal abnormalities in Queensland, is described. The six independent cytogenetic laboratories serving the population of 2.2 million contribute data to the register which provides total population information on the occurrence of chromosomal abnormalities, without selection. CAROK policy on confidentiality, security, access, and safety of data is described in detail. A cytogenetic register such as this ensures a reliable permanent file of results, facilitates research, and provides a data base which will enable questions of clustering or secular trends to be answered efficiently. The register is complete for the years 1976-1981, and contains information on 880 consecutive abnormal cases; in this sense, the data constitute an unselected six-year series of diagnosed chromosomal abnormalities in Queensland. These figures show an average incidence figure (over a six-year period) for newly diagnosed cases of chromosomal abnormality of 6.61/100 000 general population per year.