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Purpose: To achieve clinical validation of cutoff values for newborn screening by tandem mass 215 spectrometry through a worldwide collaboration. Methods: Cumulative percentiles of amino 216 acids and acylcarnitines in dried blood spots of approximately 30 million normal newborns and 217 10,615 true positive cases are compared to assign clinical significance, which is achieved when 218 the median of a disease range is either >99%ile or

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Robert Clarke and colleagues conduct a meta-analysis of unpublished datasets to examine the causal relationship between elevation of homocysteine levels in the blood and the risk of coronary heart disease. Their data suggest that an increase in homocysteine levels is not likely to result in an increase in risk of coronary heart disease., Background Moderately elevated blood levels of homocysteine are weakly correlated with coronary heart disease (CHD) risk, but causality remains uncertain. When folate levels are low, the TT genotype of the common C677T polymorphism (rs1801133) of the methylene tetrahydrofolate reductase gene (MTHFR) appreciably increases homocysteine levels, so “Mendelian randomization” studies using this variant as an instrumental variable could help test causality. Methods and Findings Nineteen unpublished datasets were obtained (total 48,175 CHD cases and 67,961 controls) in which multiple genetic variants had been measured, including MTHFR C677T. These datasets did not include measurements of blood homocysteine, but homocysteine levels would be expected to be about 20% higher with TT than with CC genotype in the populations studied. In meta-analyses of these unpublished datasets, the case-control CHD odds ratio (OR) and 95% CI comparing TT versus CC homozygotes was 1.02 (0.98–1.07; p = 0.28) overall, and 1.01 (0.95–1.07) in unsupplemented low-folate populations. By contrast, in a slightly updated meta-analysis of the 86 published studies (28,617 CHD cases and 41,857 controls), the OR was 1.15 (1.09–1.21), significantly discrepant (p = 0.001) with the OR in the unpublished datasets. Within the meta-analysis of published studies, the OR was 1.12 (1.04–1.21) in the 14 larger studies (those with variance of log OR, Editors' Summary Background Coronary heart disease (CHD) is the leading cause of death among adults in developed countries. With age, fatty deposits (atherosclerotic plaques) coat the walls of the coronary arteries, the blood vessels that supply the heart with oxygen and nutrients. The resultant restriction of the heart's blood supply causes shortness of breath, angina (chest pains that are usually relieved by rest), and sometimes fatal heart attacks. Many established risk factors for CHD, including smoking, physical inactivity, being overweight, and eating a fat-rich diet, can be modified by lifestyle changes. Another possible modifiable risk factor for CHD is a high blood level of the amino acid homocysteine. Methylene tetrahydofolate reductase, which is encoded by the MTHFR gene, uses folate to break down and remove homocysteine so fortification of cereals with folate can reduce population homocysteine blood levels. Pooled results from prospective observational studies that have looked for an association between homocysteine levels and later development of CHD suggest that the reduction in homocysteine levels that can be achieved by folate supplementation is associated with an 11% lower CHD risk. Why Was This Study Done? Prospective observational studies cannot prove that high homocysteine levels cause CHD because of confounding, the potential presence of other unknown shared characteristics that really cause CHD. However, an approach called “Mendelian randomization” can test whether high blood homocysteine causes CHD. A common genetic variant of the MTHFR gene—the C677T polymorphism—reduces MTHFR efficiency so TT homozygotes (individuals in whom both copies of the MTHFR gene have the nucleotide thymine at position 677; the human genome contains two copies of most genes) have 25% higher blood homocysteine levels than CC homozygotes. In meta-analyses (statistical pooling of the results of several studies) of published Mendelian randomized studies, TT homozygotes have a higher CHD risk than CC homozygotes. Because gene variants are inherited randomly, they are not subject to confounding, so this result suggests that high blood homocysteine causes CHD. But what if only Mendelian randomization studies that found an association have been published? Such publication bias would affect this aggregate result. Here, the researchers investigate the association of the MTHFR C677T polymorphism with CHD in unpublished datasets that have analyzed this polymorphism incidentally during other genetic studies. What Did the Researchers Do and Find? The researchers obtained 19 unpublished datasets that contained data on the MTHFR C677T polymorphism in thousands of people with and without CHD. Meta-analysis of these datasets indicates that the excess CHD risk in TT homozygotes compared to CC homozygotes was 2% (much lower than predicted from the prospective observational studies), a nonsignificant difference (that is, it could have occurred by chance). When the probable folate status of the study populations (based on when national folic acid fortification legislation came into effect) was taken into account, there was still no evidence that TT homozygotes had an excess CHD risk. By contrast, in an updated meta-analysis of 86 published studies of the association of the polymorphism with CHD, the excess CHD risk in TT homozygotes compared to CC homozygotes was 15%. Finally, in a meta-analysis of randomized trials on the use of vitamin B supplements for homocysteine reduction, folate supplementation had no significant effect on the 5-year incidence of CHD. What Do These Findings Mean? These analyses of unpublished datasets are consistent with lifelong moderate elevation of homocysteine levels having no significant effect on CHD risk. In other words, these findings indicate that circulating homocysteine levels within the normal range are not causally related to CHD risk. The meta-analysis of the randomized trials of folate supplementation also supports this conclusion. So why is there a discrepancy between these findings and those of meta-analyses of published Mendelian randomization studies? The discrepancy is too large to be dismissed as a chance finding, suggest the researchers, but could be the result of publication bias—some studies might have been prioritized for publication because of the positive nature of their results whereas the unpublished datasets used in this study would not have been affected by any failure to publish null results. Overall, these findings reveal a serious example of publication bias and argue against the use of folate supplements as a means of reducing CHD risk. Additional Information Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001177. The American Heart Association provides information about CHD and tips on keeping the heart healthy; it also provides information on homocysteine, folic acid, and CHD, general information on supplements and heart health, and personal stories about CHD The UK National Health Service Choices website provides information about CHD, including personal stories about CHD Information is available from the British Heart Foundation on heart disease and keeping the heart healthy The US National Heart Lung and Blood Institute also provides information on CHD (in English and Spanish) MedlinePlus provides links to many other sources of information on CHD (in English and Spanish) Wikipedia has a page on Mendelian randomization (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)

Serious hematological, metabolic and neurological complications owing to the nutritional deficiency of vitamin B12 may occur in infants of mothers on a strict vegetarian diet.The mother of the first child was a strict vegetarian. She had an elevated urinary methylmalonic acid level and a low concentration of serum vitamin B12. Her 13-month-old daughter was exclusively breast-fed until the age of 9 month and then she was fed only vegetables. Physical examination revealed psychomotoric retardation, apathy, muscular hypotonia, abnormal movements and failure to thrive. Laboratory analysis showed a megaloblastic anaemia, a low level of vitamin B12 and methylmalonic aciduria. MRI of the brain revealed diffuse frontotemporoparietal atrophy and retardation of myelination. After treatment with vitamin B12 supplements, abnormal movements disappeared and development improved, but a mild generalised hypotonia continued. A cranial MRI 9 months after treatment still showed signs of retardation of myelination. The second patient, an 8 month-old male, son of a strict vegetarian mother too, was referred for investigation of psychomotoric retardation, hypotonia, dyskinesia, failure to thrive and microcephaly. He was breast-fed and from 6 month of age he had also received fruit juices. Laboratory analysis revealed megaloblastic anaemia, high methylmalonic aciduria and homocystinuria. The patient's and his mother's serum level of vitamin B12 were low. After treatment with vitamin B12 supplements, biochemical and metabolic markers of disease were normal but there continued a generalised hypotonia, microcephaly and language delay.Our observations emphasize the health complications of nutritional cobalamine deficiency and a requirement of clinical, biochemical and metabolic monitoring in infants within strict vegetarian families.

Homocystinuria due to cystathionine beta-synthase deficiency is an autosomal recessive disorder of methionine metabolism. It manifests with vascular, central nervous system and connective tissue disturbances, and phenotypically resembles Marfan's syndrome. We analysed the clinical course of homocystinuria in Czech and Slovak patients.The group of homocystinuric patients consisted of 19 individuals (12 males and 7 females) aged 5-32 years (average age 18 years), who were diagnosed between 1980 and 1999. The overall incidence of homocystinuria in the Czech and Slovak Republics was 1:287,000. The proportion of pyridoxine-responsive patients was 47%. The average follow-up period was 10 years (range 1 month to 19 years). The prevalence of the individual signs in the group was as follows: lens dislocation--95% of patients, progressive myopia--79%, marfanoid habitus--74%, kyfoscoliosis--68%, osteoporosis--63%, psychomotor retardation--58%, other neurologic symptomatology--58% and tromboembolism--21%. The average delay between the first sign of the disease and the time when the diagnosis was made was 4 years (range 1 to 14 years). At the time of diagnosis the average levels of metabolites in plasma were as follows: total homocysteine 348 mumol/l (range 211-536), free homocystine 70 mumol/l (range 0-203) and methionine 359 mumol/l (range 75-937).Both the clinical course of homocystinuria due to the cystathionine beta-synthase deficiency and its incidence in the Czech and Slovak Republics are similar to those in other populations. Since homocystinuria is a treatable disease, it should be included in the differential diagnosis of Marfan's syndrome, tromboembolism and severe psychomotor retardation.

Elevated phenylalanine levels in maternal blood (hyperphenylalaninaemia) during pregnancy damages the developing foetal tissues. Early detection of pregnant women with hyperphenylalaninaemia and adherence to a low phenylalanine diet already before conception and throughout pregnancy can prevent this damage. The objective of the investigation are results achieved screening and strict monitoring of low phenylalanine dietetic treatment in detected pregnant women of the Prague population.186 350 healthy women of the Prague population were examined by the chromatographic screening test in a venous blood sample during their first visit in a maternity welfare centre and 22 positive cases were detected (incidence 1:8470). In 86% mild, persistent or benign forms of phenylketonuria were involved. Nineteen patients were treated by a low phenylalanine diet and the phenylalanine tolerance was monitored as well as the nitrogen balance, amino acids in serum and urine, protein markers, trace elements, vitamins, lipids, the body mass index-BMI, changes of body weight after introduction of the dietetic treatment and treatment during pregnancy. A significant increase of the phenylalanine tolerance by 20 to 200% was found, mostly in the second half of pregnancy and reduced values of serum and urinary selenium. The decrease of body weight when the diet was introduced and the increment during pregnancy correlated with the BMI value. In the other investigated parameters no significant deviations were found.Fifteen healthy children with normal psychomotor development delivered by 12 mothers with hyperphenylalaninaemia provide evidence of the effectiveness of prenatal screening for hyperphenylalaninaemia during pregnancy.