Biomedical subjects
Publications and source records attributed to W van't Hoff.
We describe five babies, who were exclusively breast fed, with life-threatening complications of hypernatraemic dehydration secondary to inadequate breast feeding. An increased awareness among health professionals is required so that this potentially devastating condition can be prevented.
BACKGROUND: Renal venous thrombosis (RVT) is the most common form of venous thrombosis in neonates, causing both acute and long term kidney dysfunction. Historical predisposing factors include dehydration, maternal diabetes, and umbilical catheters, but recent reports highlight associations with prothrombotic abnormalities. STUDY: Twenty three patients with neonatal RVT were analysed over 15 years. Predisposing factors, presentation, and procoagulant status were compared with renal outcome using multilevel modelling. RESULTS: Median presentation was on day 1: 19/23 (83%) had pre/perinatal problems, including fetal distress (14), intrauterine growth retardation (five), and pre-identified renal abnormalities (two); 8/18 (44%) had procoagulant abnormalities, particularly factor V Leiden mutations (4/18). Long term abnormalities were detected in 28/34 (82%) affected kidneys; mean glomerular filtration rate was 93.6 versus 70.2 ml/min/1.73 m2 in unilateral versus bilateral cases (difference 23.4; 95% confidence interval 6.4 to 40.4; p = 0.01). No correlation was observed between procoagulant tendencies and outcome, but presenting renal length had a significant negative correlation: mean fall in estimated single kidney glomerular filtration rate was 3 ml/min/1.73 m2 (95% confidence interval 3.7 to -2.2; p = 0.001) per 1 mm increase, and kidneys larger than 6 cm at presentation never had a normal outcome. CONCLUSIONS: This subgroup of neonatal RVT would be better termed perinatal RVT to reflect antenatal and birth related antecedents. Prothrombotic defects should be considered in all patients with perinatal RVT. Kidney length at presentation correlated negatively with renal outcome. The latter, novel observation raises the question of whether larger organs should be treated more aggressively in future.
Branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder involving hearing loss, branchial defects, ear pits and renal abnormalities. Oto-facio-cervical (OFC) syndrome is clinically similar to BOR syndrome, with clinical features in addition to those of BOR syndrome. Mutations in the EYA1 gene (localised to 8q13.3) account for nearly 70% of BOR syndrome cases exhibiting at least three of the major features. Small intragenic deletions of the 3' region of the gene have also been reported in patients with BOR syndrome. We have developed a fluorescent quantitative multiplex polymerase chain reaction for three 3' exons (7, 9 and 13) of the EYA1 gene. This dosage assay, combined with microsatellite marker analysis, has identified de novo deletions of the EYA1 gene and surrounding region in two patients with complex phenotypes involving features of BOR syndrome. One patient with OFC syndrome carried a large deletion of the EYA1 gene region, confirming that OFC syndrome is allelic with BOR syndrome. Microsatellite analysis has shown that comparison of the boundaries of this large deletion with other reported rearrangements of the region reduces the critical region for Duane syndrome (an eye movement disorder) to between markers D8S553 and D8S1797, a genetic distance of approximately 1 cM.
OBJECTIVE: The objective was to assess the efficacy and safety of growth hormone (GH) treatment in severely growth retarded children with nephropathic cystinosis during conservative treatment and during renal replacement therapy. STUDY DESIGN: The design was an open-labeled prospective trial with a run-in period of 1 year. RESULTS: A total of 74 children with cystinosis (age 3.0 to 18 years) were treated with GH over a mean period of 3.1 years (range 1 to 10 years); 52 patients were receiving conservative treatment (mean age 7.1 years), 7 were receiving dialysis (12.5 years), and 15 had received a renal transplant (14.8 years). The mean standardized height (SD score) was -4.0 in the conservative treatment group, -4.4 in the dialysis group, and -4.9 in the renal transplant group. During the first treatment year, height velocity doubled in the conservative treatment group, increased by 80% in the dialysis group, and increased by 45% in renal transplant group. Within 3 years the height SD score increased by +1.6 (P <.001) in prepubertal patients receiving conservative treatment, and percentile parallel growth was maintained thereafter. These effects of GH were less expressed in peripubertal patients receiving renal replacement therapy. No major side effects were observed. CONCLUSION: Long-term GH treatment is safe and effective in young children with nephropathic cystinosis. GH treatment should be started early in the course of the disease if adequate nutrition and cysteamine treatment do not prevent growth retardation.
AIM: To describe the clinical phenotype in infants with ARC syndrome, the association of arthrogryposis, renal tubular acidosis, and cholestasis. METHODS: The medical records for six patients with ARC syndrome were reviewed, presenting over 10 years to three paediatric referral centres. RESULTS: All patients had the typical pattern of arthrogryposis. Renal Fanconi syndrome was present in all but one patient, who presented with nephrogenic diabetes insipidus. Although all patients had severe cholestasis, serum gamma glutamyltransferase values were normal. Many of our patients showed dysmorphic features or ichthyosis. All had recurrent febrile illnesses, diarrhoea, and failed to thrive. Blood films revealed abnormally large platelets. CONCLUSIONS: ARC syndrome exhibits notable clinical variability and may not be as rare as previously thought. The association of Fanconi syndrome, ichthyosis, dysmorphism, jaundice, and diarrhoea has previously been reported as a separate syndrome: our observations indicate that it is part of the ARC spectrum.
UNLABELLED: The outcome for children with severe forms of methylmalonic acidaemia remains poor. Patients have recurrent episodes of metabolic decompensation; many have neurodevelopmental complications and the mortality is high. Long-term survivors develop chronic renal failure. Because of the poor prognosis, transplantation has been considered. In young patients with early onset disease, liver transplantation might prevent complications and, for those in end-stage renal failure, kidney transplantation could be combined with that of the liver. The results of liver transplantation in the early onset patients have generally been disappointing. In particular there appears to be a high risk of neurological complications. The optimal management of those in end-stage renal failure has not yet been determined although combined liver and kidney transplantation has been successful. CONCLUSION: The role of transplantation in methylmalonic acidaemia has yet to be established and follow up of all patients who are considered for transplantation is essential.
UNLABELLED: Nephrocalcinosis (NC) is a complication of the treatment of X-linked hypophosphatemic rickets (XLHR). Some studies have found that treated patients have enteric hyperoxaluria caused by phosphate therapy and have implicated calcium oxalate, whereas others have found only calcium phosphate in renal biopsy tissue. AIM AND METHODS: We aimed to study the urinary supersaturation of calcium oxalate and calcium phosphate and to determine whether these measures are risk factors for NC. We collected 24-hour urine samples from 20 patients (12 girls) with XLHR, mean +/- SD age 8.2 +/- 4.7 years, and from 79 age-matched members of a healthy control group prospectively. RESULTS: The median 24-hour urine excretions of oxalate, phosphate, and citrate (mmol/1.73 m(2) per day) were significantly increased in patients compared with the control group (oxalate 0.38 vs 0.28, P =. 0012; phosphate 63.1 vs 25.8, P <.0001; citrate 4.18 vs 2.7, P =. 0002). However, no significant differences were seen in the calcium oxalate or calcium phosphate between patients and the control group. No significant differences were seen in 24-hour urine calcium or magnesium excretion between patients and the control group; however, 8 patients had hypercalciuria. A significant higher urine volume in patients compared with the normal group (826 mL/m(2) 24-hour vs 597 mL/m(2) 24-hour; P <.005) was found. Twelve patients had NC at the time of investigation, and although the oxalate excretion was significantly higher in these patients, no significant difference was seen in the relative supersaturation of calcium oxalate monohydrate (CaC(2)O(4).H(2)O) compared with the 8 without NC. CONCLUSIONS: Although 24-hour urine oxalate and phosphate excretion are increased in treated patients with XLHR, there is no increase in the supersaturation of either calcium oxalate or phosphate. Determination of the supersaturation of calcium oxalate or calcium phosphate does not predict the development of NC in XLHR.
Nephropathic cystinosis is an autosomal recessive disorder that is characterized by accumulation of intralysosomal cystine and is caused by a defect in the transport of cystine across the lysosomal membrane. Using a positional cloning strategy, we recently cloned the causative gene, CTNS, and identified pathogenic mutations, including deletions, that span the cystinosis locus. Two types of deletions were detected-one of 9.5-16 kb, which was seen in a single family, and one of approximately 65 kb, which is the most frequent mutation found in the homozygous state in nearly one-third of cystinotic individuals. We present here characterization of the deletion breakpoints and demonstrate that, although both deletions occur in regions of repetitive sequences, they are the result of nonhomologous recombination. This type of mechanism suggests that the approximately 65-kb deletion is not a recurrent mutation, and our results confirm that it is identical in all patients. Haplotype analysis shows that this large deletion is due to a founder effect that occurred in a white individual and that probably arose in the middle of the first millenium. We also describe a rapid PCR-based assay that will accurately detect both homozygous and heterozygous deletions, and we use it to show that the approximately 65-kb deletion is present in either the homozygous or the heterozygous state in 76% of cystinotic patients of European origin.
Infantile nephropathic cystinosis is a rare, autosomal recessive disease caused by a defect in the transport of cystine across the lysosomal membrane and characterized by early onset of renal proximal tubular dysfunction. Late-onset cystinosis, a rarer form of the disorder, is characterized by onset of symptoms between 12 and 15 years of age. We previously characterized the cystinosis gene, CTNS, and identified pathogenic mutations in patients with infantile nephropathic cystinosis, including a common, approximately 65 kb deletion which encompasses exons 1-10. Structure predictions suggested that the gene product, cystinosin, is a novel integral lysosomal membrane protein. We now examine the predicted effect of mutations on this model of cystinosin. In this study, we screened patients with infantile nephropathic cystinosis, those with late-onset cystinosis and patients whose phenotype does not fit the classical definitions. We found 23 different mutations in CTNS; 14 are novel mutations. Out of 25 patients with infantile nephropathic cystinosis, 12 have two severely truncating mutations, which is consistent with a loss of functional protein, and 13 have missense or in-frame deletions, which would result in disruption of transmembrane domains and loss of protein function. Mutations found in two late-onset patients affect functionally unimportant regions of cystinosin, which accounts for their milder phenotype. For three patients, the age of onset of cystinosis was <7 years but the course of the disease was milder than the infantile nephropathic form. This suggests that the missense mutations found in these individuals allow production of functional protein and may also indicate regions of cystinosin which are not functionally important.
Nephropathic cystinosis, an autosomal recessively inherited lysosomal storage disease, results from impaired transport of the disulfide amino acid cystine out of cellular lysosomes. The consequent accumulation and crystallization of cystine destroys tissues, causing growth retardation in infancy, renal failure at 10 years of age, and a variety of other complications. Early oral therapy with the cystine-depleting agent cysteamine prevents renal deterioration and enhances growth. Although the lysosomal cystine carrier has been extensively studied, its molecular structure remains unknown. The lysosomal cystine transporter gene has been mapped by linkage analysis to human chromosome 17p between polymorphic microsatellite markers D17S1583 and D17S1584. Pertinent recombination events and homozygosity by descent has verified that the cystinosis gene lies in the 3.6 cM genetic interval between these two markers. The cystinosis region has been substantially reduced in size by the observation of recombination events in cystinosis patients between markers D17S1828 and D17S2167. According to radiation hybrid analysis, these two markers are separated by 10.2 cR8000 (centirad using 8000 rad radiation hybrids). Estimates of the physical size of this interval range from 187 to 510 kb. Four yeast artificial chromosomes have been identified which form a contig covering the original cystinosis region. Two P1 clones together may span the new, smaller interval, meaning that the cystinosis gene would lie on one of them. Current efforts are being directed toward using these P1 clones to isolate candidate cDNAs by a variety of methods. The ultimate cloning of the cystinosis gene will reveal how functional lysosomal porters are synthesized, targeted, processed, and integrated into the lysosomal membrane.
Nephropathic cystinosis, an autosomal recessive disorder resulting from defective lysosomal transport of cystine, is the most common inherited cause of renal Fanconi syndrome. The cystinosis gene has been mapped to chromosome 17p13. We found that the locus D17S829 was homozygously deleted in 23 out of 70 patients, and identified a novel gene, CTNS, which mapped to the deletion interval. CTNS encodes an integral membrane protein, cystinosin, with features of a lysosomal membrane protein. Eleven different mutations, all predicted to cause loss of function of the protein, were found to segregate with the disorder.
Infantile nephropathic cystinosis is an autosomal recessive disorder characterized biochemically by an abnormally high intracellular content of free cystine in different organs and tissues due to a transport defect of cystine through the lysosomal membrane. Affected children present with the Fanconi syndrome and usually develop progressive renal failure within the 1st decade of life. Measurement of free cystine in purified polymorphonuclear leukocytes provides an accurate method for diagnosis and detection of heterozygous carriers. In order to localize the gene locus for cystinosis we performed linkage analysis in 18 cystinosis families. However, since 17 of these were simplex families, we decided to include the phenotypes of the heterozygous carriers previously determined by their leukocyte cystine content in the linkage analysis. This approach allowed us to obtain highly significant results, confirming the localization of the cystinosis gene locus recently mapped to the short arm of chromosome 17 by the Cystinosis Collaborative Research Group. Crucial recombination events allowed us to refine the interval of the cystinosis gene to a genetic distance of 1 cM. No evidence of genetic heterogeneity was found. Our results demonstrate that the use of the previously determined phenotypes of heterozygous carriers in linkage analysis provides a reliable method for the investigation of simplex families in autosomal recessive traits.
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Sixty-eight patients with mild primary hyperparathyroidism were studied for a mean period of 4.5 years (median 3.3). Seven of these patients presented with renal colic while the rest had no symptoms. There was no significant deterioration in mean serum creatinine, total calcium or ionized calcium concentrations during this period. No patient had progressive renal stone or parathyroid bone disease. Hypertension was defined as a systolic or diastolic blood pressure greater than one standard deviation from the age-sex mean, or if hypotensive drugs were required. Thirty-nine per cent were hypertensive at presentation and 42 per cent became hypertensive later. Four patients died from causes unrelated to hypercalcaemia and three required parathyroidectomy when serum calcium concentration rose above 3.0 mmol/l. Patients over 55 with mild asymptomatic primary hyperparathyroidism may be managed conservatively for several years without significant renal impairment, progressive stone disease, parathyroid bone disease or worsening hypercalcaemia. We suggest that observation in these patients could be restricted to six-monthly checks of physical state, blood pressure and serum biochemistry, particularly concentration of calcium creatinine and alkaline phosphatase.
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