Deficiency or inhibition of lysophosphatidic acid receptor 1 protects against hyperoxia-induced lung injury in neonatal rats.

AIM: Blocking of lysophosphatidic acid (LPA) receptor (LPAR) 1 may be a novel therapeutic option for bronchopulmonary dysplasia (BPD) by preventing the LPAR1-mediated adverse effects of its ligand (LPA), consisting of lung inflammation, pulmonary arterial hypertension (PAH) and fibrosis. METHODS: In Wistar rats with experimental BPD, induced by continuous exposure to 100% oxygen for 10 days, we determined the beneficial effects of LPAR1 deficiency in neonatal rats with a missense mutation in cytoplasmic helix 8 of LPAR1 and of LPAR1 and -3 blocking with Ki16425. Parameters investigated included survival, lung and heart histopathology, fibrin and collagen deposition, vascular leakage and differential mRNA expression in the lungs of key genes involved in LPA signalling and BPD pathogenesis. RESULTS: LPAR1-mutant rats were protected against experimental BPD and mortality with reduced alveolar septal thickness, lung inflammation (reduced influx of macrophages and neutrophils, and CINC1 expression) and collagen III deposition. However, LPAR1-mutant rats were not protected against alveolar enlargement, increased medial wall thickness of small arterioles, fibrin deposition and vascular alveolar leakage. Treatment of experimental BPD with Ki16425 confirmed the data observed in LPAR1-mutant rats, but did not reduce the pulmonary influx of neutrophils, CINC1 expression and mortality in rats with experimental BPD. In addition, Ki16425 treatment protected against PAH and right ventricular hypertrophy. CONCLUSION: LPAR1 deficiency attenuates pulmonary injury by reducing pulmonary inflammation and fibrosis, thereby reducing mortality, but does not affect alveolar and vascular development and, unlike Ki16425 treatment, does not prevent PAH in neonatal rats with experimental BPD.

A survey of natural protein intake in Dutch phenylketonuria patients: insight into estimation or measurement of dietary intake.

This study investigated which methods patients and parents used to determine phenylalanine (Phe) intake and the relationship between the methods applied, age, and blood Phe concentration, as this practice had not been studied before in relation to metabolic control. A questionnaire was sent to 327 Dutch phenylketonuria patients (age 0-29 years) to investigate the method used to determine Phe intake (either by estimation, exact measurement, or a combination of both). Mean blood Phe concentration of each individual patient was related to the method reported to be used. Three different age groups (<10 years, > or =10-15 years, and > or =16 years) were distinguished. The response rate for the questionnaires was 73%. In these 188 patients, data for both Phe concentrations and questionnaires could be used. Of these, 75 used exact measurement, 75 used estimation, and 38 used both methods. The number of patients that estimated Phe intake clearly increased with age. Whatever method was used, an increase in Phe concentrations was seen with age. During childhood, exact measurement was used more frequently, and from adolescence on estimation was used more frequently. The method (exact measurement and/or estimation) did not result in statistically different Phe concentrations in any of the three age groups, although blood Phe concentration tended to be lower in adolescence using exact measurement. Data suggest that estimation and exact measurement of Phe intake are both reliable methods. Therefore, in addition to exact measurement, patients should be instructed in both methods at an early age, so that both methods can be used adequately.

Effects of midazolam and morphine on cerebral oxygenation and hemodynamics in ventilated premature infants.

BACKGROUND: Midazolam sedation and morphine analgesia are commonly used in ventilated premature infants. OBJECTIVES: To evaluate the effects of midazolam versus morphine infusion on cerebral oxygenation and hemodynamics in ventilated premature infants. METHODS: 11 patients (GA 26.6-33.0 weeks, BW 780-2,335 g) were sedated with midazolam (loading dose 0.2 mg/kg, maintenance 0.2 mg/kg/h) and 10 patients (GA 26.4-33.3 weeks, BW 842-1,955 g) were sedated with morphine (loading dose 0.05 mg/kg, maintenance 0.01 mg/kg/h). Changes in oxyhemoglobin (Delta cO2Hb) and deoxyhemoglobin (Delta cHHb) were assessed using near infrared spectrophotometry. Changes in cHbD (= Delta cO(2)Hb - Delta cHHb) reflect changes in cerebral blood oxygenation and changes in concentration of total hemoglobin (Delta ctHb = Delta cO2Hb + Delta cHHb) represent changes in cerebral blood volume (DeltaCBV). Changes in cerebral blood flow velocity (DeltaCBFV) were intermittently measured using Doppler ultrasound. Heart rate (HR), mean arterial blood pressure (MABP), arterial oxygen saturation (saO2) and transcutaneous measured pO2 (tcpO2) and pCO2 (tcpCO2) were continuously registered. Statistical analyses were carried out using linear mixed models to account for the longitudinal character study design. RESULTS: Within 15 min after the loading dose of midazolam, a decrease in saO2, tcpO2 and cHbD was observed in 5/11 infants. In addition, a fall in MABP and CBFV was observed 15 min after midazolam administration. Immediately after morphine infusion a decrease in saO2, tcpO2 and cHbD was observed in 6/10 infants. Furthermore, morphine infusion resulted in a persistent increase in CBV. CONCLUSIONS: Administration of midazolam and morphine in ventilated premature infants causes significant changes in cerebral oxygenation and hemodynamics, which might be harmful.

Effects of rapid versus slow infusion of sodium bicarbonate on cerebral hemodynamics and oxygenation in preterm infants.

BACKGROUND: Sodium bicarbonate (NaHCO3) is often used for correction of metabolic acidosis in preterm infants. The effects of NaHCO3 administration on cerebral hemodynamics and oxygenation are not well known. Furthermore, there is no consensus on infusion rate of NaHCO3. OBJECTIVES: To evaluate the effects of rapid versus slow infusion of NaHCO3 on cerebral hemodynamics and oxygenation in preterm infants. METHODS: Twenty-nine preterm infants with metabolic acidosis were randomized into two groups (values are mean +/-SD): In group A (GA 30.5 +/- 1.7 weeks, b.w. 1,254 +/- 425 g) NaHCO3 4.2% was injected as a bolus. In group B (GA 30.3 +/- 1.8 weeks, b.w. 1,179 +/- 318 g) NaHCO3 4.2% was administered over a 30-min period. Concentration changes of oxyhemoglobin (cO2Hb) and deoxyhemoglobin (cHHb) were assessed using near infrared spectrophotometry. Changes in HbD (= cO2Hb - cHHb) represent changes in cerebral blood oxygenation and changes in ctHb (= cO2Hb + cHHb) reflect changes in cerebral blood volume. Cerebral blood flow velocity was intermittently measured using Doppler ultrasound. Longitudinal data analysis was performed using linear mixed models (SAS procedure MIXED), to account for the fact that the repeated observations in each individual were correlated. RESULTS: Administration of NaHCO3 resulted in an increase of cerebral blood volume which was more evident if NaHCO3 was injected rapidly than when infused slowly. HbD and cerebral blood flow velocity did not show significant changes in either group. CONCLUSION: To minimize fluctuations in cerebral hemodynamics, slow infusion of sodium bicarbonate is preferable to rapid injection.

Smith-Lemli-Opitz syndrome and the DHCR7 gene.

Smith-Lemli-Opitz syndrome, a severe developmental disorder associated with multiple congenital anomalies, is caused by a defect of cholesterol biosynthesis. Low cholesterol and high concentrations of its direct precursor, 7-dehydrocholesterol, in plasma and tissues are the diagnostic biochemical hallmarks of the syndrome. The plasma sterol concentrations correlate with severity and disease outcome. Mutations in the DHCR7 gene lead to deficient activity of 7-dehydrocholesterol reductase (DHCR7), the final enzyme of the cholesterol biosynthetic pathway. The human DHCR7 gene is localised on chromosome 11q13 and its structure has been characterized. Ninety-one different mutations in the DHCR7 gene have been published to date. This paper is a review of the clinical, biochemical and molecular genetic aspects.

Prerequisites and strategies for prenatal diagnosis of respiratory chain deficiency in chorionic villi.

Prenatal diagnosis for respiratory chain deficiencies is a complex procedure that requires a thorough diagnostic work-up of the index patient. This includes confirmation of the clinical and metabolic evaluations through histological and enzymatic examinations of tissue biopsies. Prenatal diagnosis currently relies on biochemical assays of respiratory chain complexes in chorionic villi or amniocytes and is possible by mutation analysis of nuclear genes in a limited but increasing proportion of cases. Based on a recent survey of prenatal diagnosis in families with complex I and complex IV deficiencies, performed at Nijmegen Centre for Mitochondrial Disorders (NCMD), prerequisites and strategies for performing prenatal diagnosis have been developed to increase reliability. Biochemical investigations in chorionic villi can be done reliably if the respiratory chain enzyme deficiency is expressed in both skeletal muscle and skin fibroblasts to rule out tissue specificity. No mitochondrial DNA defects must be suspected or established. The NCMD does not offer prenatal diagnosis until all the prerequisites have been confirmed. We expect prenatal diagnosis at the molecular level to become more feasible in time as the mutational spectrum broadens with advances in medical research.

Prenatal diagnosis of NADH:ubiquinone oxidoreductase deficiency.

NADH:ubiquinone oxidoreductase (complex I of the mitochondrial respiratory chain) deficiency is a severe disorder with an often early fatal outcome. Prenatal diagnosis for complex I defects currently relies mainly on biochemical assays of complex I in fetal tissues such as chorionic villi (CV), and is only in a minority of cases possible by means of mutational analysis of nuclear-encoded genes of complex I. We report on our experience to date with prenatal diagnosis in pregnancies at risk for complex I deficiency. We measured complex I activity in native CV and/or cultured CV in 23 pregnancies in 15 families. In accordance with the results of the investigations in CV, 15 children were born clinically unaffected. Two prenatally diagnosed unaffected fetuses and two prenatally diagnosed affected fetuses were lost prematurely with spontaneous or provoked abortions, respectively. Two affected children were born (prenatally found to be affected). In two pregnancies a discrepancy between native and cultured cells was found. We conclude that prenatal diagnosis for complex I deficiency can be reliably performed. Pitfalls were encountered in using cultured CV as a result of maternal cell contamination (MCC). Future research on pathogenic nuclear mutations underlying complex I deficiency will extend the possibilities for prenatal diagnosis at the molecular level.

Human NADH:ubiquinone oxidoreductase.

NADH:ubiquinone oxidoreductase consists of at least 43 proteins; seven are encoded by the mitochondrial genome, while the remainder are encoded by the nuclear genome. A deficient activity of this enzyme complex is frequently observed in the clinical heterogeneous group of mitochondrial disorders, with Leigh (-like) disease as the main contributor. Enzyme complex activity measurement in skeletal muscle is the mainstay of the diagnostic process. Fibroblast studies are a prerequisite whenever prenatal enzyme diagnosis is considered. Mitochondrial DNA mutations are found in approximately 5-10% of all complex I deficiencies. Recently, all structural nuclear complex I genes have been determined at the cDNA level and several at the gDNA level. A comprehensive mutational analysis study of all complex I nuclear genes in a group of 20 patients exhibiting this deficiency revealed mutations in about 40%. Here, we describe the enzymic methods we use and the recent progress made in genomics and cell biology of human complex I.

Growth hormone treatment in children with Noonan's syndrome: four year results of a partly controlled trial.

UNLABELLED: The aim of the study was to evaluate the effect of continuous and discontinuous growth hormone treatment in Noonan's syndrome (NS) on linear growth and bone maturation. Thirty-seven children with NS aged between 5.4 and 17.5 y were treated with growth hormone (GH) in a dose of 0.15 IU kg)(-1) per day; 23 of these children were randomly assigned to one of 2 groups in a 3 y partly controlled prospective multicentre study. Group A (n = 8) immediately started GH treatment and after 2 y discontinued GH treatment for 1 y; group B (n = 15) served as a control group during the first year and started GH treatment after 1 y. After the 3 y study period, 17 out of the 23 children continued GH treatment. An additional 14 children (group C) were treated according to the same protocol, but without discontinuation of GH treatment. The effect of GH treatment for up to 3 y was evaluated in terms of gain in height standard deviation score (H-SDS) for calendar age and for bone age. Gain in H-SDS over the first year was significantly higher in the GH treatment group (+0.5) than in the non-treated group (+0.0); mean bone maturation was significantly faster in the GH treatment group (1.2 vs 0.5 y/y). Discontinuation in group A in the third study year resulted in catch-down growth (mean deltaH-SDS -0.2). Over 3 y of GH treatment, mean AH-SDS for calendar age was not significantly different between discontinuous (A: +0.8) and continuous treatment (B: +0.8; C: +1.2). Mean gain in H-SDS for bone age in the 3 groups (+0.2, 0.0. +0.3) was minimal after 3 y of GH treatment. CONCLUSION: This study confirmed the gain in H-SDS CA in Noonan's syndrome during long-term GH treatment. However, the accelerating effect of GH on bone maturation seemed to compromise the final height prognosis.

Infantile presentation of the mtDNA A3243G tRNA(Leu (UUR)) mutation.

Mitochondrial DNA (mtDNA) disorders are clinically very heterogeneous, ranging from single organ involvement to severe multisystem disease. One of the most frequently observed mtDNA mutations is the A-to-G transition at position 3243 of the tRNA(Leu (UUR)) gene. This mutation is often related to MELAS syndrome. However, not all patients with the A3243G mutation share the same clinical disease expression and, on the contrary, patients clinically exhibiting MELAS syndrome may have other mtDNA mutations. Here we describe two patients with a very early infantile presentation of disease associated with the A3243G mutation. Patient 1 presented with hypotonia, feeding difficulties and failure to thrive (FTT) at the age of 3 months. Laboratory investigations showed persistent hyperlactic acidemia, elevated lactate/pyruvate ratios and elevated alanine concentrations in blood. Developmental delay was progressive and he developed cardiomyopathy and seizures. Death occurred at the age of 3.5 years. Patient 2 was born prematurely and had persistent, severe lactic acidosis from birth on. Moderate biventricular hypertrophy was seen on ultrasound studies of the heart and, suffering from progressive lactic acidosis, he died at the age of 13 days. Because of the rarity of this very early presentation, we searched the literature for other infantile cases associated with the A3243G mutation and found 8 additional ones. In infants presenting with lactic acidosis/hyperlactic acidemia, failure to thrive, hypotonia, seizures and/or cardiomyopathy, mtDNA mutational analysis, also for the disease entities, usually only observed in juveniles or adults is warranted.

Basal metabolic rate in children with a solid tumour.

OBJECTIVE: To study the level of and changes in basal metabolic rate (BMR) in children with a solid tumour at diagnosis and during treatment in order to provide a more accurate estimate of energy requirements for nutritional support. DESIGN: An observational study. SETTING: Tertiary care at the Centre for Paediatric Oncology, University Hospital Nijmegen. SUBJECTS: Thirteen patients were recruited from a population of patients visiting the University Hospital Nijmegen for treatment. All patients asked to participate took part in and completed the study. INTERVENTION: BMR was measured by indirect calorimetry, under stringent, standardised conditions, for 20 min and on three different occasions in all patients. Continuous breath gas analysis using a mouthpiece was performed. Weight, height and skinfold measurements were performed before each measurement. MAIN OUTCOME MEASURES: BMR was expressed as percentage of the estimated reference value, according to the Schofield formulas based on age, weight and sex, and in kJ (kcal) per kg of fat-free mass. RESULTS: At diagnosis, the BMR was higher than the estimated reference BMR in all patients and 44% of the patients were considered hypermetabolic. Mean BMR (as percentage of reference) was significantly increased (11.6% (s.d. 6.7%); P=0.001), but decreased during treatment in 12 of the 13 patients (mean decrease 12.7% (s.d. 3.9%); P<0.0001). Furthermore, a significant negative correlation (P=-0.67; P=0.01) was found between the change in BMR and tumour response. CONCLUSIONS: These data suggest that the BMR of children with a solid tumour is increased at diagnosis and possibly during the first phase of oncologic treatment. This may be important when determining energy requirements for nutritional support.

Novel mutations in the 7-dehydrocholesterol reductase gene of 13 patients with Smith--Lemli--Opitz syndrome.

Smith--Lemli--Opitz syndrome (SLOS) is caused by mutations in the DHCR7 gene leading to deficient activity of 7-dehydrocholesterol reductase (DHCR7; EC 1.3.1.21), the final enzyme of the cholesterol biosynthetic pathway, resulting in low cholesterol and high concentrations of its direct precursor 7-dehydrocholesterol in plasma and tissues. We here report mutations identified in the DHCR7 gene of 13 children diagnosed with SLOS by clinical and biochemical criteria. We found a high frequency of the previously described IVS8--1 G > C splice acceptor site mutation (two homozygotes, eight compound heterozygotes). In addition, 13 missense mutations and one splice acceptor mutation were detected in eleven patients with a mild to moderate SLOS-phenotype. The mutations include three novel missense mutations (W182L, C183Y, F255L) and one novel splice acceptor site mutation (IVS8--1 G > T). Two patients, homozygous for the IVS8--1 G > C mutation, presented with a severe clinical phenotype and died shortly after birth. Seven patients with a mild to moderate SLOS-phenotype disclosed compound heterozygosity of the IVS8--1 G > C mutation in combination with different novel and known missense mutations.

Growth hormone (GH) secretion in children with Noonan syndrome: frequently abnormal without consequences for growth or response to GH treatment.

The role of GH insufficiency in the pathogenesis of short stature in Noonan syndrome is unclear. Cross-sectional study. Seventeen patients with Noonan syndrome (13 boys, 4 girls; aged 4.8-13.3 (mean 9.2) years) and short stature before start of GH treatment. Spontaneous 12-h overnight GH secretion by continuous sampling analysed using Pulsar, plasma IGF-I and IGFBP-3 levels, and 24-h urinary GH excretion were measured at start of GH treatment. A glucagon stimulation test was performed. Height and height velocity were monitored before and after 1 year of GH treatment. IGF-I and IGFBP-3 were remeasured after 1 year of GH treatment. Nine of the 17 children had a mean overnight GH concentration below the lower limit of the normal range. In six of the 17 patients, overnight GH profiles showed high trough GH concentrations. Glucagon stimulation tests were normal in 16 of the 17 patients. Mean IGF-I level was below normal (-0.4 SD). None of the parameters regarding GH secretion obtained from the overnight profile or provocative test was related to height or height velocity, nor to first year response to GH treatment. IGF-I and IGFBP-3 did not correlate with any of the GH secretion data. IGF-I and IGFBP-3 were related to height and height velocity at the start of GH treatment (r = 0.53 (P < 0.01) and r = 0.61 (P < 0.03) respectively). Rises in IGF-I and IGFBP-3 under GH treatment were related to the increment in height velocity (r = 0.70 (P < 0.01) and r = 0.71 (P < 0.02) respectively). Abnormalities in GH secretion are frequent in patients with Noonan syndrome and short stature. These abnormalities were not related to auxology at start of or response to GH treatment. Clinically GH insufficiency is not important in Noonan syndrome and monitoring spontaneous GH secretion is not necessary before the start of GH treatment.

Mutations in the complex I NDUFS2 gene of patients with cardiomyopathy and encephalomyopathy.

Human complex I is built up and regulated by genes encoded by the mitochondrial DNA (mtDNA) as well as the nuclear DNA (nDNA). In recent years, attention mainly focused on the relation between complex I deficiency and mtDNA mutations. However, a high percentage of consanguinity and an autosomal-recessive mode of inheritance observed within our patient group as well as the absence of common mtDNA mutations make a nuclear genetic cause likely. The NDUFS2 protein is part of complex I of many pro- and eukaryotes. The nuclear gene coding for this protein is therefore an important candidate for mutational detection studies in enzymatic complex I deficient patients. Screening of patient NDUFS2 cDNA by reverse transcriptase-polymerase chain reaction (RT-PCR) in combination with direct DNA sequencing revealed three missense mutations resulting in the substitution of conserved amino acids in three families.

Nasogastric tube feeding in children with cancer: the effect of two different formulas on weight, body composition, and serum protein concentrations.

BACKGROUND: Treatment of cancer cachexia partly involves the administration of adequate amounts of energy. The aim of this study was to assess the tolerance and efficacy of two equal volumes of tube feeding, one with a standard (1 kcal/mL) and one with a high energy density (1.5 kcal/mL), during the intensive phase of treatment. METHODS: Nutritional status was assessed weekly, in 27 children with a solid tumor, by measuring weight, height, midupper arm circumference, biceps and triceps skinfold, and serum proteins. Tolerance was assessed by recording the occurrence of vomiting and by expressing the administered volume as a percentage of the required volume. RESULTS: Both formulas were equally well tolerated, leading to a significantly higher energy intake in the energy-enriched formula group. In both formula groups, all anthropometric variables increased significantly (range of mean increase, 5.2% to 25.5%; p < .05) during the first 4 weeks of intervention. Between 4 and 10 weeks, variables continued to increase significantly in the energy-enriched group, resulting in adequate repletion, in contrast to the standard formula group. The concentration of serum proteins, low at initiation of tube feeding, returned to the normal range within 2 to 4 weeks with no significant differences between the two groups. CONCLUSIONS: The energy-enriched formula was more effective in improving the nutritional status of children with cancer during the intensive phase of treatment than the standard formula. Intensive, protocolized administration of an energy-enriched formula should therefore be initiated as soon as one of the criteria for initiation of tube feeding is met.

Association between the change in nutritional status in response to tube feeding and the occurrence of infections in children with a solid tumor.

In 32 children with a solid tumor, the association between the change in weight for height, in response to 4 weeks of tube feeding during the intensive phase of treatment, and the occurrence of leukopenia, leukopenic infections, and nonleukopenic infections in a period thereafter (4-10 weeks) was studied. Factors possibly influencing the change in weight for height during the first 4 weeks of tube feeding were also assessed. A statistically significant negative correlation (rho = -0.59; p < .001) was found between the change in z-score of weight for height in response to the first 4 weeks of tube feeding, and the occurrence of nonleukopenic infections between 4 and 10 weeks. A reduced occurrence of nonleukopenic infections resulted in a significant reduction of the number of days of infection-related hospital admission (rho = .45; p = .009), which, besides providing advantages for the patient, also had economical benefits. The change in weight for height in response to tube feeding was mainly influenced by the incidence of therapy-induced vomiting (r = -.45; p = .02) and by the amount of energy provided by tube feeding (r = .47; p = .007). Based on these findings, it is recommended that naso-gastric tube feeding be used in children with a solid tumor during the early intensive phase of treatment, and that one should aim for a considerable increase in weight for height during the first 4 weeks of administration, since this has been shown to reduce the number of nonleukopenic infections in a subsequent period. The increase in weight for height may be improved by providing an optimal antiemetic protocol, which will increase energy uptake, and an energy-enriched formula, which will increase energy intake.

A prognostic index as diagnostic strategy in children suspected of mitochondriocytopathy.

The aim of this study was to assess an optimal screening for paediatric patients suspected of mitochondriocytopathy to justify a muscle biopsy. Forty-five patients were included. Medical history, physical examination, cardiac and ophthalmologic evaluation, clinical chemical investigations, in vivo function tests, neuroimaging and a skeletal muscle biopsy were performed in all patients. The results of the biochemical muscle studies were compared with the results of the other investigations. First, parameters with a statistical relationship with the result in muscle, normal or deficient, were selected. Secondly, a prognostic index was constructed using these parameters. Five parameters were selected: age <4 years, elevated fasting lactate to pyruvate ratio, elevated thrombocyte count, elevated lactate, and elevated alanine. Each parameter was scored 0 (not present) or 1 (present). The chance of a normal biopsy with a given value of this index (sum of the scores) was calculated: logit (Pr) = alpha + beta x index; alpha: -0.8167 and beta: 0.8331. (Pr: probability of normal biopsy.) The chance of a normal biopsy with an index value of 5 is 0.03, 4 is 0.07, 3 is 0.16, 2 is 0.30, 1 is 0.50 and 0 is 0.69. This prognostic index is a valuable instrument in deciding whether the suspicion of mitochondriocytopathy is strong enough to merit a muscle biopsy.

Simvastatin. A new therapeutic approach for Smith-Lemli-Opitz syndrome.

The Smith-Lemli-Opitz syndrome (SLOS) is caused by deficient Delta(7)-dehydrocholesterol reductase, which catalyzes the final step of the cholesterol biosynthetic pathway, resulting in low cholesterol and high concentrations of its direct precursors 7-dehydrocholesterol (7DHC) and 8DHC. We hypothesized that i) 7DHC and 8DHC accumulation contributes to the poor outcome of SLOS patients and ii) blood exchange transfusions with hydroxymethylglutaryl (HMG)-CoA reductase inhibition would improve the precursor-to-cholesterol ratio and may improve the clinical outcome of SLO patients. First, an in vitro study was performed to study sterol exchange between plasma and erythrocyte membranes. Second, several exchange transfusions were carried out in vivo in two SLOS patients. Third, simvastatin was given for 23 and 14 months to two patients. The in vitro results illustrated rapid sterol exchange between plasma and erythrocyte membranes. The effect of exchange transfusion was impressive and prompt but the effect on plasma sterol levels lasted only for 3 days. In contrast, simvastatin treatment for several months demonstrated a lasting improvement of the precursor-to-cholesterol ratio in plasma, erythrocyte membranes, and cerebrospinal fluid (CSF). Plasma precursor concentrations decreased to 28 and 33% of the initial level, respectively, whereas the cholesterol concentration normalized by a more than twofold increase. During the follow-up period all morphometric parameters improved. The therapy was well tolerated and no unwanted clinical side effects occurred. This is the first study in which the blood cholesterol level in SLOS patients is normalized with a simultaneous significant decrease in precursor levels. There was a lasting biochemical improvement with encouraging clinical improvement. Statin therapy is a promising novel approach in SLOS that deserves further studies in larger series of patients.

Clinical differences in patients with mitochondriocytopathies due to nuclear versus mitochondrial DNA mutations.

Defects in oxidative phosphorylation (OXPHOS) are genetically unique because the different components involved in this process, respiratory chain enzyme complexes (I, III, and IV) and complex V, are encoded by nuclear and mitochondrial genome. The objective of the study was to assess whether there are clinical differences in patients suffering from OXPHOS defects caused by nuclear or mitochondrial DNA (mtDNA) mutations. We studied 16 families with > or = two siblings with a genetically established OXPHOS deficiency, four due to a nuclear gene mutation and 12 due to a mtDNA mutation. Siblings with a nuclear gene mutation showed very similar clinical pictures that became manifest in the first years (ranging from first months to early childhood). There was a severe progressive course. Seven of the eight children died in their first decade. Conversely, siblings with a mtDNA mutation had clinical pictures that varied from almost alike to very distinct. They became symptomatic at an older age (ranging from childhood to adulthood), with the exception of defects associated with Leigh or Leigh-like phenotype. The clinical course was more gradual and relatively less severe; four of the 26 patients died, one in his second year, another in her second decade and two in their sixth decade. There are differences in age at onset, severity of clinical course, outcome, and intrafamilial variability in patients affected of an OXPHOS defect due to nuclear or mtDNA mutations. Patients with nuclear mutations become symptomatic at a young age, and have a severe clinical course. Patients with mtDNA mutations show a wider clinical spectrum of age at onset and severity. These differences may be of importance regarding the choice of which genome to study in affected patients as well as with respect to genetic counseling.

Isolated complex I deficiency in children: clinical, biochemical and genetic aspects.

We retrospectively examined clinical and biochemical characteristics of 27 patients with isolated enzymatic complex I deficiency (established in cultured skin fibroblasts) in whom common pathogenic mtDNA point mutations and major rearrangements were absent. Clinical phenotypes present in this group are Leigh syndrome (n = 7), Leigh-like syndrome (n = 6), fatal infantile lactic acidosis (n = 3), neonatal cardiomyopathy with lactic acidosis (n = 3), macrocephaly with progressive leukodystrophy (n = 2), and a residual group of unspecified encephalomyopathy (n = 6) subdivided into progressive (n = 4) and stable (n = 2) variants. Isolated complex I deficiency is one of the most frequently observed disturbance of the OXPHOS system. Respiratory chain enzyme assays performed in cultured fibroblasts and skeletal muscle tissue in general reveal similar results, but for complete diagnostics we recommend enzyme measurements performed in at least two different tissues to minimize the possibility of overlooking the enzymatic diagnosis. Lactate levels in blood and CSF and cerebral CT/MRI studies are highly informative, although normal findings do not exclude complex I deficiency. With the discovery of mutations in nuclear encoded complex I subunits, adequate pre- and postnatal counseling becomes available. Finally, considering information currently available, isolated complex I deficiency in children seems to be caused in the majority by mutations in nuclear DNA.