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.

A homozygous nonsense mutation in the methylmalonyl-CoA epimerase gene (MCEE) results in mild methylmalonic aciduria.

Methylmalonic aciduria (MMA-uria) is an autosomal recessive inborn error of amino acid metabolism, involving valine, threonine, isoleucine, and methionine. This organic aciduria may present in the neonatal period with life-threatening metabolic acidosis, hyperammonemia, feeding difficulties, pancytopenia, and coma. Most affected patients have mutations in the methylmalonyl-coenzyme A (methylmalonyl-CoA) mutase gene. Mildly affected patients may present in childhood with failure to thrive and recurrent attacks of metabolic acidosis. Both a higher residual activity of methylmalonyl-CoA mutase as well as the vitamin B12-responsive defects (cblA and cblB) may form the basis of the mild disorder. A few patients with moderate MMA-uria are known in whom no defect could be identified. Here we present a 16-year-old female patient with persisting moderate MMA-uria (approximately 50 mmol/mol creatinine). She was born to consanguineous Caucasian parents. Her fibroblast mutase activity was normal and no effect of vitamin B12 supplementation could be established. Reduced incorporation of 14C-propionate into macromolecules suggested a defect in the propionate-to-succinate pathway. We found a homozygous nonsense mutation (c.139C>T) in the methylmalonyl-CoA epimerase gene (MCEE), resulting in an early terminating signal (p.R47X). Both parents were heterozygous for this mutation; they were found to excrete normal amounts of methylmalonic acid (MMA). This is the first report of methylmalonyl-CoA epimerase deficiency, thereby unequivocally demonstrating the biochemical role of this enzyme in human metabolism.

Riboflavin-responsive complex I deficiency.

Three patients from a large consanguineous family, and one unrelated patient had exercise intolerance since early childhood and improved by supplementation with a high dosage of riboflavin. This was confirmed by higher endurance power in exercise testing. Riboflavin had been given because complex I, which contains riboflavin in FMN, one of its prosthetic groups, had a very low activity in muscle. Histochemistry showed an increase of subsarcolemmal mitochondria. The low complex I activity contrasted with an increase of the activities of succinate dehydrogenase, succinate-cytochrome c oxidoreductase and cytochrome c oxidase. Isolated mitochondria from these muscle specimens proved deficient in oxidizing pyruvate plus malate and other NAD(+)-linked substrates, but oxidized succinate and ascorbate at equal or higher levels than controls. Two years later a second biopsy was taken in one of the patients, and the activity of complex I had increased from 16% to 47% of the average activity in controls. In the four biopsies, cytochrome c oxidase activity correlated negatively with age. We suspect that this is due to reactive oxygen species generated by the proliferating mitochondria and peroxidizing unsaturated fatty acids of cardiolipin. Three of the four patients had low blood carnitine, and all were found to have hypocarnitinemic family members.

Two Novel Mutations in the SLC25A4 Gene in a Patient with Mitochondrial Myopathy.

In a 28-year-old male with a mild mitochondrial myopathy manifesting as exercise intolerance and early signs of cardiomyopathy without muscle weakness or ophthalmoplegia, we identified two novel mutations in the SLC25A4 gene: c.707G>C in exon 3 (p.(R236P)) and c.116_137del in exon 2 (p.(Q39Lfs*14)). Serum lactate levels at rest were elevated (12.7 mM). Both the patient's father and brother were heterozygous carriers of the c.707G>C mutation and were asymptomatic. The second mutation causes a 22 bp deletion leading to a frame shift likely giving rise to a premature stop codon and nonsense-mediated decay (NMD). The segregation of the mutations could not be tested directly as the mother had died before. However, indirect evidence from NMD experiments showed that the two mutations were situated on two different alleles in the patient. This case is unique compared to other previously reported patients with either progressive external ophthalmoplegia (PEO) or clear hypertrophic cardiomyopathy with exercise intolerance and/or muscle weakness carrying recessive mutations leading to a complete absence of the SLC25A4 protein. Most likely in our patient, although severely reduced, SLC25A4 is still partially present and functional.

Human alpha-N-acetylgalactosaminidase (alpha-NAGA) deficiency: no association with neuroaxonal dystrophy?

Two new individuals with alpha-NAGA deficiency are presented. The index patient, 3 years old, has congenital cataract, slight motor retardation and secondary demyelinisation. Screening of his sibs revealed an alpha-NAGA deficiency in his 7-year-old healthy brother who had no clinical or neurological symptoms. Both sibs are homozygous for the E325K mutation, the same genotype that was found in the most severe form of alpha-NAGA deficiency presenting as infantile neuroaxonal dystrophy. Thus, at the age of 7 years the same genotype of alpha-NAGA may present as a 'non-disease' (present healthy case) and can be associated with the vegetative state (the first two patients described with alpha-NAGA deficiency). The clinical heterogeneity among the 11 known individuals with alpha-NAGA deficiency is extreme, with a 'non-disease' (two cases) and infantile neuroaxonal dystrophy (two cases) at the opposite sides of the clinical spectrum. The broad spectrum is completed by a very heterogeneous group of patients with various degrees of epilepsy/behavioural difficulties/psychomotor retardation (four patients) and a mild phenotype in adults without overt neurological manifestations who have angiokeratoma and clear vacuolisation in various cell types (three cases). These observations are difficult to reconcile with a straightforward genotype-phenotype correlation and suggest that factors or genes other than alpha-NAGA contribute to the clinical heterogeneity of the 11 patients with alpha-NAGA deficiency.

Macrocephaly, facial abnormalities, disproportionate tall stature, and mental retardation--a sib observation.

We report on two brothers with relatively short limbs, macrocephaly, high and narrow forehead, frontal upsweep of hairline, hypotelorism, broad but short ears, straight back, and mild hypermobility of all joints. Both were hypotonic neonatally and had developmental delay and behavior problems. Several of the manifestations were present in the father, too. A literature search failed to uncover any similar case.

MR imaging and proton spectroscopy in 3-hydroxy-3-methylglutaryl coenzyme A lyase deficiency.

Three patients with 3-hydroxy-3-methylglutaryl coenzyme A lyase deficiency were examined with MR imaging and proton MR spectroscopy. In two patients, both clinically normal, MR images showed a diffuse mild abnormality in signal intensity of the cerebral white matter, with multiple foci of more pronounced signal abnormality superimposed. In the third patient, who was clinically retarded and had a cerebral visual impairment, MR imaging showed, in addition to a diffuse signal abnormality of the cerebral white matter, atrophic scarring of the occipital lobes and abnormal signal intensity of the thalami and basal ganglia. It is highly probable that the additional lesions in the occipital lobes and basal nuclei were related to the episode of severe neonatal hypoglycemia the patient experienced. The MR spectroscopic abnormalities correlated with the degree of disease as evidenced by MR imaging.

Some kinetic properites of liver ornithine carbamoyl transferase (OCT) in a patient with OCT deficiency.

Some kinetic properties of liver OCT from a patient with OCT deficiency were studied. Contrary to controls, in which two pH optima were observed (pH 7.7 and pH 8.5), only the pH optimum of 8.5 could be demonstrated in our patient. From KM studies at pH 7.7 and pH 8.5, the most striking abnormalities in comparison with human controls were (a) a strongly increased KM (ornithine) at pH 7.7, but less pronounced at pH 8.5, (b) a higher VMAX at pH 8.5 compared with the VMAX at pH 7.7 and (c) the absence of substate inhibition at pH 8.5 to ornithine was elevated up to a concentration above approximately 1.5 mM.

Methylmalonate excretion in a pregnancy at risk for methylmalonic acidaemia.

In a pregnant woman, who had given birth to a child with methylmalonic acidaemia previously, urinary methylmalonate was measured at various intervals in the second half of the pregnancy. A significant increase was observed towards term. The child proved to be affected. This procedure enabled the detection of an affected fetus in the third trimester of pregnancy. If a case of methylmalonic acidaemia is detected in this way, treatment can be started immediately after birth.

Tyrosinemia and tyrosyluria in healthy prematures: time courses not vitamin C-dependent.

Tyrosyluria and for a part also tyrosinemia were studied in 60 healthy prematures of various birth weights and gestational ages. The first analyses were performed between the 6th and the 14th day after birth. A normal milk diet was given and the protein-intake was between 3 and 4 g/kg. After the first collection of urine half the patients received extra ascorbic acid, 100 mg/kg daily. Urinary analyses of tyrosine and p-hydroxyphenyl metabolites were performed once a week, until the excretion of p-hydroxyphenylpyruvic plus p-hydroxyphenyllactic acids was lower than 5 mmoles per gram creatinine. In 22 out of the 60 prematures (or 37%) a tyrosyluria of more than 5 mmoles/g creatinine and in 19 out of 44 (43%) patients analysed serum tyrosine was higher than 5 mg/100 ml at first analysis. No inverse correlation between tyrosyluria and tyrosinemia on the one hand and birth weight and gestational age on the other hand existed. But in children with a delayed intra-uterine development the incidence of tyrosyluria was higher as prematurity was more pronounced. Ascorbic acid had no effect on the rate of disappearance of tyrosyluria. It was concluded that the addition of extra vitamin C to the diet of prematures is not useful for the normalization of tyrosine metabolism.

Compound heterozygosity for a known and a novel defect in the lipoprotein lipase gene (Asp250-->Asn; Ser251-->Cys) resulting in lipoprotein lipase (LPL) deficiency.

Two missense mutations in exon 6 of the LPL gene were identified on separate alleles in a Dutch patient with lipoprotein lipase (LPL) deficiency. The first mutation is a G1003-->A transition resulting in a D250N mutation, which has been shown previously to result in a catalytically defective protein in patients of French-Canadian ancestry. The second mutation, a C to G transition at nucleotide 1007, predicts a S251C residue change in the highly conserved region of LPL surrounding the loop structure the covers the catalytic triad. This mutation constitutes a novel defect among LPL gene mutations reported so far. Site-directed mutagenesis experiments provide in-vitro evidence for the complete loss of LPL activity resulting from this latter missense mutation. The G1003-->A nucleotide substitution underlying the Asp250 mutation deletes a TaqI endonuclease recognition site and the C1007-->G change that leads to the S251C alteration abolishes a HinfI recognition site. This will facilitate rapid screening for these mutations in LPL-deficient patients.

[Is detection and treatment of familial hypercholesterolemia indicated in children?]. / Is opsporing en behandeling van familiaire hypercholesterolemie geïndiceerd bij kinderen?

Familial hypercholesterolaemia (FH) is a congenital metabolic disorder predisposing to severe atherosclerosis resulting in coronary heart disease sometimes even at early adult age. Children with FH lack the stigmata at physical examination and measuring the cholesterol level does not always enable the clinician to make the diagnosis. In about 70% of the cases, the diagnosis of FH in childhood can be made by means of molecular-biological examination, by demonstrating the underlying defect of the LDL cholesterol receptor gene. In the remaining cases, the combination of the positive family history for cardiovascular diseases and increased total cholesterol and LDL cholesterol levels should suggest the diagnosis of FH. Pharmaceutical agents inhibiting the cholesterol synthesis have been researched very little in children and are not registered in the Netherlands. Nevertheless, drug treatment of children with FH is advisable because of the better possibilities to make a definite diagnosis and the early occurrence of coronary heart disease. If this treatment were indicated before patients reach adult age, the question arises whether screening for FH of children in families in which this disorder prevails, should not be promoted more strongly.

[From gene to disease; galactosemia and galactose-1-phosphate uridyltransferase deficiency]. / Van gen naar ziekte; galactosemie en galactose-I-fosfaaturidyltransferasedeficiëntie.

Classical galactosaemia (Mendelian Inheritance in Man, no 230400) is an autosomal recessive disorder of galactose metabolism caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT). The GALT enzyme is responsible for the conversion of galactose-1-phosphate with UDP glucose to glucose-1-phosphate and UDP galactose. The gene encoding for GALT is located on chromosome 9p13. Patients present with hepatomegaly, liver failure, food intolerance, hypoglycaemia, muscle hypotonia, sepsis and cataract. Treatment involving the total restriction of lactose-containing foods is life-saving but many patients develop late complications such as problems of mental development, disorders of motor function, disorders of speech and hypergonadotrophic hypogonadism.

[Type I tricho-rhino-phalangeal syndrome]. / Het tricho-rhino-falangeaal syndroom, type I.

A two-year-old boy and his mother with the Tricho-Rhino-Phalangeal syndrome type I were studied. The mother showed the complete triad of the syndrome with fine, sparse, slow-growing hair, pear-shaped nose and abnormal fingers. Cone-shaped epiphyses of the phalanges of the hands and shortening of the mesophalanges and of the first and fifth metacarpals were observed radiographically. With the exception of the extreme shortening of several phalanges and metacarpals the above mentioned symptoms were also present in the son.

[Severe complications following an adeno-tonsillectomy in a patient with Hunter's syndrome (MPS II)]. / Ernstige complicaties na een ate bij een patiënt met de ziekte van Hunter (MPS II).

The history of an 11-year old boy with Hunter-syndrome is presented who developed respiratory and haemostatic complications following adenoidectomy and tonsillectomy because of grossly enlarged and chronically infected adenoid and tonsils and recurrent upper respiratory infections.

[A patient with an unclassifiable form of neuroaxonal dystrophy]. / Een patiënt met een niet nader in te delen vorm van een infantiele neuro-axonale dystrofie.

The authors describe the clinical history of a boy with progressive neurological abnormalities from the age of nine months. After death at the age of four years, histopathological examination demonstrated an unknown form of infantile neuro-axonal dystrophy.

[A patient with the homozygote form of familial hypercholesterolemia]. / Een patiënt met de homozygote vorm van familiaire hypercholesterolemie.

The history of an 11 year old boy with homozygous familial hypercholesterolemia with therapeutic response to cholesterol lowering drugs is presented. Symptoms, laboratory diagnosis and therapeutic problems are discussed.