Extending the new era of genomic testing into pregnancy management: A proposed model for Australian prenatal services.

BACKGROUND: Trio exome sequencing can be used to investigate congenital abnormalities identified on pregnancy ultrasound, but its use in an Australian context has not been assessed. AIMS: Assess clinical outcomes and changes in management after expedited genomic testing in the prenatal period to guide the development of a model for widespread implementation. MATERIALS AND METHODS: Forty-three prospective referrals for whole exome sequencing, including 40 trios (parents and pregnancy), two singletons and one duo were assessed in a tertiary hospital setting with access to a state-wide pathology laboratory. Diagnostic yield, turn-around time (TAT), gestational age at reporting, pregnancy outcome, change in management and future pregnancy status were assessed for each family. RESULTS: A clinically significant genomic diagnosis was made in 15/43 pregnancies (35%), with an average TAT of 12 days. Gestational age at time of report ranged from 16 + 5 to 31 + 6 weeks (median 21 + 3 weeks). Molecular diagnoses included neuromuscular and skeletal disorders, RASopathies and a range of other rare Mendelian disorders. The majority of families actively used the results in pregnancy decision making as well as in management of future pregnancies. CONCLUSIONS: Rapid second trimester prenatal genomic testing can be successfully delivered to investigate structural abnormalities in pregnancy, providing crucial guidance for current and future pregnancy management. The time-sensitive nature of this testing requires close laboratory and clinical collaboration to ensure appropriate referral and result communication. We found the establishment of a prenatal coordinator role and dedicated reporting team to be important facilitators. We propose this as a model for genomic testing in other prenatal services.

Isolated autism is not an indication for Smith-Lemli-Opitz syndrome biochemical testing.

Several studies have demonstrated a high incidence of autistic spectrum features in individuals with Smith-Lemli-Opitz syndrome (SLOS). However, do these findings imply a converse relationship that has diagnostic utility? Is SLOS testing implicated when autism spectrum disorder (ASD) is the only clinical indication? AIM: To determine if there is any correlation with a clinical indication of ASD and a biochemical diagnosis of SLOS, based on historical test request and assay data. METHODS: Six years (2008-2013) of clinical test requests for 7-dehydrocholesterol (7-DHC) level were classified and summarised according to indication and final test result. RESULTS: From the audit period, 988 valid test results from post-natal samples were identified. In plasma/serum, mean 7-DHC level was 264.7 µmol/L (normal range < 2.0) for confirmed SLOS cases. No tests performed due to an isolated clinical indication of ASD or where no clinical information was supplied were associated with 7-DHC levels diagnostic for SLOS. CONCLUSIONS: Historical test data analysis supports the recommendation that autism/ASD as a single clinical feature is not an appropriate indication for SLOS (7-DHC) biochemical testing.

Expanding the clinical utility of glucosylsphingosine for Gaucher disease.

Gaucher disease (GD) is an inherited metabolic disorder characterised by impaired catabolism of the glycosphingolipid, glucosylceramide. The deacetylated derivative, glucosylsphingosine (GluSph, lyso-Gb1) has materialised as a biomarker for GD. Further appraisal of the clinical utility of GluSph is required in terms of its prognostic power to inform disease course and pre-symptomatic testing. In this study, we show that plasma GluSph concentrations are significantly higher in GD patients with neuronopathic disease compared with non-neuronopathic disease, even in the neonatal period. A neonate diagnosed at 1 day of age (homozygous for N370S) due to an affected older sibling, returned GluSph of 70 nmol/L compared with 1070-2620 nmol/L for four neuronopathic patients diagnosed <20 days of age. Given this result shows promise for newborn screening, we developed a rapid, simple, and robust assay for GluSph in dried filter paper blood spots (DBS) and were able to detect 23 GD patients from 220 unaffected individuals. Neuronopathic GD patients also had significantly higher DBS concentrations of GluSph than their non-neuronopathic counterparts. We went on to measure GluSph in tissue extracts prepared from chorionic villus sampling and confirmed concentrations were undetectable in unaffected tissue but elevated in GD tissue demonstrating utility in the prenatal setting. Additionally, GluSph is a pharmacodynamic biomarker, revealing a precipitous drop following initiation of enzyme replacement therapy. In conclusion, GluSph is a reliable and specific biomarker for GD and shows promise for prenatal diagnosis and DBS screening programmes.

Disease and subtype specific signatures enable precise diagnosis of the mucopolysaccharidoses.

PURPOSE: Expanding treatments for the mucopolysaccharidoses-a family of genetic disorders-place unprecedented demands for accurate, timely diagnosis because best outcomes are seen with early initiation of appropriate therapies. Here we sought to improve the diagnostic odyssey by measuring specific glycosaminoglycan fragments with terminal residues complicit with the genetic defect resulting in precise diagnosis rather than the usual first-line, ambiguous total glycosaminoglycan determinations that return poor diagnostic yield. METHODS: A derivatizing reagent was added to urine aliquots (0.5 µmol creatinine) before separation of the glycosaminoglycan fragments by liquid chromatography and quantification with electrospray ionization-tandem mass spectrometry using multiple reaction monitoring for 10 targeted fragments plus the internal standard. RESULTS: All 93 mucopolysaccharidosis patients were correctly identified as 1 of 10 subtypes from a total of 723 de-identified subjects-blinded to diagnosis-based on the presence of specific "signature" glycosaminoglycan fragments. Employing reference intervals calculated from 630 unaffected urines, with 99% confidence intervals, provided a laboratory test with 100% specificity and sensitivity. CONCLUSION: This novel urine assay allows diagnosis of 10 mucopolysaccharidosis subtypes in a single test. The precise quantification of unique glycosaminoglycan fragments also enables longitudinal biochemical monitoring following therapeutic interventions.

A simple method for quantification of plasma globotriaosylsphingosine: Utility for Fabry disease.

Fabry disease (FD) results from impaired globotriaosylceramide (Gb3) catabolism, due to a deficiency of the lysosomal hydrolase, α-galactosidase A (α-GalA). As a direct consequence, the deacetylated derivative, globotriaosylsphingosine (lyso-Gb3), is produced and contemporary evidence exemplifies its use as a biomarker. Here we developed a simple method to enable quantification of lyso-Gb3 in just 0.01mL of plasma and explored its concentration in a cohort of 73 Australian FD patients, as well as in individuals with other sphingolipidoses. In 2000 patients without FD, but with related metabolic conditions, lyso-Gb3 returned concentrations of <5pmol/mL. In the FD cohort, 53/60 patients with classical mutations returned lyso-Gb3 concentrations≥5pmol/mL whereas only 4/13 patients with "late-onset" mutations had lyso-Gb3≥5pmol/mL. Five females with normal α-GalA activity and genetically confirmed FD returned lyso-Gb3≥5pmol/mL. The prevalence of clinically significant disease including cardiomyopathy, nephropathy and cerebrovascular disease was congruent with higher lyso-Gb3 concentrations. Repeat testing was available for 51 patients-26 undergoing enzyme replacement therapy-and concentrations of lyso-Gb3 remained unaltered throughout 6-18 months independent of sex, mutation or treatment status. Our data suggest that the optimum use of lyso-Gb3 resides in laboratory confirmation of classical FD and for monitoring at least the initial response to therapeutic intervention. There is no evidence that lyso-Gb3 can inform on clinical events.

Pathogen-induced rapid evolution in a vertebrate life-history trait.

Anthropogenic factors, including climate warming, are increasing the incidence and prevalence of infectious diseases worldwide. Infectious diseases caused by pathogenic parasites can have severe impacts on host survival, thereby altering the selection regime and inducing evolutionary responses in their hosts. Knowledge about such evolutionary consequences in natural populations is critical to mitigate potential ecological and economic effects. However, studies on pathogen-induced trait changes are scarce and the pace of evolutionary change is largely unknown, particularly in vertebrates. Here, we use a time series from long-term monitoring of perch to estimate temporal trends in the maturation schedule before and after a severe pathogen outbreak. We show that the disease induced a phenotypic change from a previously increasing to a decreasing size at maturation, the most important life-history transition in animals. Evolutionary rates imposed by the pathogen were high and comparable to those reported for populations exposed to intense human harvesting. Pathogens thus represent highly potent drivers of adaptive phenotypic evolution in vertebrates.

Enzyme replacement therapy "drug holiday": results from an unexpected shortage of an orphan drug supply in Australia.

The development of recombinantly manufactured enzyme replacement therapy (ERT) has revolutionised the management of some inherited disorders of metabolism. Gaucher disease was the first lysosomal storage disorder for which ERT became commercially available and ERT remains first-line treatment for affected individuals. In Australia, 70 patients with Gaucher disease are treated through a centrally administered Australian Government national program known as the Life Savings Drug Program (LSDP). Imiglucerase (Cerezyme), manufactured by Genzyme Corporation, is the only ERT currently registered in Australia for the treatment of Gaucher disease. In June 2009, Genzyme Corporation announced the detection of a virus in its Allston Landing manufacturing facility which resulted in inventories of imiglucerase being insufficient to meet projected global demand. The Australian Government sought advice from its Gaucher Disease Advisory Committee (GDAC) on recalculating patient doses in order to ration available imiglucerase to those most in need on a clinical severity basis. Management of this rationing process was urgent and required extensive investigation to develop a clinical severity hierarchy, to review available imiglucerase stock spread across multiple pharmacies, to implement a strategy for redistributing available imiglucerase according to specific patients' recalculated doses, to advise treating doctors and patients concerning these changed circumstances and to consider new monitoring schedules during the drug shortage phase. A cohort of 24 patients was withdrawn from therapy, 22 of whom had no discernable clinical adverse effect. This experience suggests that short-term studies of maintenance therapy without a no-treatment arm may lead to erroneous conclusions and that some patients may have treatment holidays or delayed infusions without short-term adverse outcomes.

Antagonistic selection from predators and pathogens alters food-web structure.

Selection can alter predator-prey interactions. However, whether and how complex food-webs respond to selection remain largely unknown. We show in the field that antagonistic selection from predators and pathogens on prey body-size can be a primary driver of food-web functioning. In Windermere, U.K., pike (Esox lucius, the predator) selected against small perch (Perca fluviatilis, the prey), while a perch-specific pathogen selected against large perch. The strongest selective force drove perch trait change and ultimately determined the structure of trophic interactions. Before 1976, the strength of pike-induced selection overrode the strength of pathogen-induced selection and drove a change to larger, faster growing perch. Predation-driven increase in the proportion of large, infection-vulnerable perch presumably favored the pathogen since a peak in the predation pressure in 1976 coincided with pathogen expansion and a massive perch kill. After 1976, the strength of pathogen-induced selection overrode the strength of predator-induced selection and drove a rapid change to smaller, slower growing perch. These changes made perch easier prey for pike and weaker competitors against juvenile pike, ultimately increasing juvenile pike survival and total pike numbers. Therefore, although predators and pathogens exploited the same prey in Windermere, they did not operate competitively but synergistically by driving rapid prey trait change in opposite directions. Our study empirically demonstrates that a consideration of the relative strengths and directions of multiple selective pressures is needed to fully understand community functioning in nature.

Fatal perinatal mitochondrial cardiac failure caused by recurrent de novo duplications in the ATAD3 locus.

BACKGROUND: In about half of all patients with a suspected monogenic disease, genomic investigations fail to identify the diagnosis. A contributing factor is the difficulty with repetitive regions of the genome, such as those generated by segmental duplications. The ATAD3 locus is one such region, in which recessive deletions and dominant duplications have recently been reported to cause lethal perinatal mitochondrial diseases characterized by pontocerebellar hypoplasia or cardiomyopathy, respectively. METHODS: Whole exome, whole genome and long-read DNA sequencing techniques combined with studies of RNA and quantitative proteomics were used to investigate 17 subjects from 16 unrelated families with suspected mitochondrial disease. FINDINGS: We report six different de novo duplications in the ATAD3 gene locus causing a distinctive presentation including lethal perinatal cardiomyopathy, persistent hyperlactacidemia, and frequently corneal clouding or cataracts and encephalopathy. The recurrent 68 Kb ATAD3 duplications are identifiable from genome and exome sequencing but usually missed by microarrays. The ATAD3 duplications result in the formation of identical chimeric ATAD3A/ATAD3C proteins, altered ATAD3 complexes and a striking reduction in mitochondrial oxidative phosphorylation complex I and its activity in heart tissue. CONCLUSIONS: ATAD3 duplications appear to act in a dominant-negative manner and the de novo inheritance infers a low recurrence risk for families, unlike most pediatric mitochondrial diseases. More than 350 genes underlie mitochondrial diseases. In our experience the ATAD3 locus is now one of the five most common causes of nuclear-encoded pediatric mitochondrial disease but the repetitive nature of the locus means ATAD3 diagnoses may be frequently missed by current genomic strategies. FUNDING: Australian NHMRC, US Department of Defense, Japanese AMED and JSPS agencies, Australian Genomics Health Alliance and Australian Mito Foundation.

Trans-generational exposure to low levels of rhodamine B does not adversely affect litter size or liver function in murine mucopolysaccharidosis type IIIA.

MPS IIIA is a lysosomal storage disorder caused by mutations in the sulphamidase gene, resulting in the accumulation of heparan sulphate glycosaminoglycans (HS GAGs). Symptoms predominantly manifest in the CNS and there is no current therapy that effectively addresses neuropathology in MPS IIIA patients. Recent studies in MPS IIIA mice have shown that rhodamine B substrate deprivation therapy (SDT) (also termed substrate reduction therapy/SRT) inhibits GAG biosynthesis and, improves both somatic and CNS disease pathology. Acute overexposure to high doses of rhodamine B results in liver toxicity and is detrimental to reproductive ability. However, the long-term effects of decreasing GAG synthesis, at the low dose sufficient to alter neurological function are unknown. A trans-generational study was therefore initiated to evaluate the continuous exposure of rhodamine B treatment in MPS IIIA mice over 4 generations, including treatment during pregnancy. No alterations in litter size, liver histology or liver function were observed. Overall, there are no long-term issues with the administration of rhodamine B at the low dose tested and no adverse effects were noted during pregnancy in mice.

Mono-symptomatic Fabry disease in a population with mild-to-moderate left ventricular hypertrophy.

Fabry disease (FD) results from a deficiency in the exoglycohydrolase, α-galactosidase A (AGA), an enzyme required for the sequential degradation of glycosphingolipids, which consequently accumulate in the lysosomes of affected cells. An X-linked inherited metabolic disorder, FD has a high incidence of a later onset phenotype that is under-diagnosed and under-recognised in adulthood despite the availability of specific treatment. As the first presenting feature in adults is often left ventricular hypertrophy (LVH), we hypothesized that testing patients with an attenuated echocardiographic phenotype of unexplained hypertrophic cardiomyopathy, might identify cases of undiagnosed FD. We employed a simple screening test by measuring AGA activity in dried blood spots collected from a finger-prick of blood in a cohort of 511 individuals aged between 18 and 75 with LVH between 1.2 and 1.5 cm. Two males were identified with AGA activity below the reference interval and subsequent molecular testing confirmed the commonly reported genetic variants, p.Ala143Thr in one individual and p.Asn215Ser, in the other. Additional biochemical measurement of plasma, lyso-Gb1 was normal in both patients. Of the 179 females screened, one individual returned AGA activity slightly below the reference interval but was lost to further follow-up. This pilot study suggests that screening patients with mild-to-moderate LVH of unknown aetiology does indeed identify undiagnosed cases of FD.

Chondroitin sulfate disaccharide is a specific and sensitive biomarker for mucopolysaccharidosis type IVA.

Mucopolysaccharidosis type IVA (MPS IVA) is an inborn error of glycosaminoglycan (GAG) catabolism characterized by a deficiency of the lysosomal enzyme, N-acetylgalactosamine 6-sulphatase (GALNS). Consequently, partially degraded GAG, chondroitin 6-sulfate (CS) and keratan sulfate (KS), accumulate in the lysosomes of affected cells, primarily in cartilage resulting in skeletal disease. Excessive urinary excretion of these GAG is often used as the initial biochemical parameter to inform a laboratory diagnosis. Here we present the utility of a CS-disaccharide with a non-reducing 6-sulfated N-acetylgalactosamine residue (HNAc-UA (1S))-the enzyme's substrate-for the diagnosis and biochemical monitoring of MPS IVA patients. Following implementation of this method into the diagnostic laboratory, we identified one MPS IVA patient over 3 years of MPS urine screening, with no false positive results from 2050 urines tested. Uniquely, urinary concentrations of HNAc-UA (1S) are independent of age meaning that age-related reference ranges are not required. Urinary HNAc-UA (1S) was also able to identify two MPS IVA siblings who remained misdiagnosed with spondyloepiphyseal dysplasia for 5 years because of normal urinary GAG. HNAc-UA (1S) could also be used as a biomarker for monitoring response to enzyme replacement therapy (ERT) as there was a drop in urinary concentration following the administration of ERT in all 12 patients and concentrations correlated with urinary KS (R 2 = 0.92). In conclusion, HNAc-UA (1S) is a reliable, sensitive and specific biomarker for the diagnosis of MPS IVA and can be used to biochemically monitor the response to ERT.

Gastrointestinal pathology in a mouse model of mucopolysaccharidosis type IIIA.

Mucopolysaccharidosis type IIIA (MPS IIIA) is a lysosomal storage disorder caused by a deficiency in sulphamidase (NS), a lysosomal enzyme required for the degradation of heparan sulphate glycosaminoglycans (gags). The MPS IIIA mouse is a naturally occurring model that accurately reflects the human pathology and disease course. It displays primarily central nervous system pathology accompanied by widespread accumulation of gag in somatic tissues. MPS IIIA mice exhibit greater bodyweight gain than normal littermates and attain a higher mature bodyweight. In this study, gastrointestinal morphology and function was characterised in the IIIA mouse. Stomach and duodenum weight increased in MPS IIIA mice and duodenum length also increased. An increased submucosal thickness was observed in MPS IIIA intestine compared to normal mice and lysosomal storage of gag was observed in this region. Storage was also observed in the lamina propria of the villus tip. All other morphometric measurements including villus height and crypt depth fell within the normal range. The gastric emptying half-life of solid and liquid meals decreased with age in normal mice whereas the T(1/2) of solid meals did not alter with age in MPS IIA mice such that they were elevated above normal by 38 weeks of age. Sucrase activity was higher than normal in MPS IIIA at all ages tested. These abnormalities in GI structure and function observed in MPS IIIA may contribute to weight gain in this disorder.

Harvest-induced disruptive selection increases variance in fitness-related traits.

The form of Darwinian selection has important ecological and management implications. Negative effects of harvesting are often ascribed to size truncation (i.e. strictly directional selection against large individuals) and resultant decrease in trait variability, which depresses capacity to buffer environmental change, hinders evolutionary rebound and ultimately impairs population recovery. However, the exact form of harvest-induced selection is generally unknown and the effects of harvest on trait variability remain unexplored. Here we use unique data from the Windermere (UK) long-term ecological experiment to show in a top predator (pike, Esox lucius) that the fishery does not induce size truncation but disruptive (diversifying) selection, and does not decrease but rather increases variability in pike somatic growth rate and size at age. This result is supported by complementary modelling approaches removing the effects of catch selectivity, selection prior to the catch and environmental variation. Therefore, fishing most likely increased genetic variability for somatic growth in pike and presumably favoured an observed rapid evolutionary rebound after fishery relaxation. Inference about the mechanisms through which harvesting negatively affects population numbers and recovery should systematically be based on a measure of the exact form of selection. From a management perspective, disruptive harvesting necessitates combining a preservation of large individuals with moderate exploitation rates, and thus provides a comprehensive tool for sustainable exploitation of natural resources.

Identification and targeted management of a neurodegenerative disorder caused by biallelic mutations in SLC5A6.

We describe a sibling pair displaying an early infantile-onset, progressive neurodegenerative phenotype, with symptoms of developmental delay and epileptic encephalopathy developing from 12 to 14 months of age. Using whole exome sequencing, compound heterozygous variants were identified in SLC5A6, which encodes the sodium-dependent multivitamin transporter (SMVT) protein. SMVT is an important transporter of the B-group vitamins biotin, pantothenate, and lipoate. The protein is ubiquitously expressed and has major roles in vitamin uptake in the digestive system, as well as transport of these vitamins across the blood-brain barrier. Pathogenicity of the identified variants was demonstrated by impaired biotin uptake of mutant SMVT. Identification of this vitamin transporter as the genetic basis of this disorder guided targeted therapeutic intervention, resulting clinically in improvement of the patient's neurocognitive and neuromotor function. This is the second report of biallelic mutations in SLC5A6 leading to a neurodegenerative disorder due to impaired biotin, pantothenate and lipoate uptake. The genetic and phenotypic overlap of these cases confirms mutations in SLC5A6 as the genetic cause of this disease phenotype. Recognition of the genetic disorder caused by SLC5A6 mutations is essential for early diagnosis and to facilitate timely intervention by triple vitamin (biotin, pantothenate, and lipoate) replacement therapy.

Four decades of opposing natural and human-induced artificial selection acting on Windermere pike (Esox lucius).

The ability of natural selection to drive local adaptation has been appreciated ever since Darwin. Whether human impacts can impede the adaptive process has received less attention. We tested this hypothesis by quantifying natural selection and harvest selection acting on a freshwater fish (pike) over four decades. Across the time series, directional natural selection tended to favour large individuals whereas the fishery targeted large individuals. Moreover, non-linear natural selection tended to favour intermediate sized fish whereas the fishery targeted intermediate sized fish because the smallest and largest individuals were often not captured. Thus, our results unequivocally demonstrate that natural selection and fishery selection often acted in opposite directions within this natural system. Moreover, the two selective factors combined to produce reduced fitness overall and stronger stabilizing selection relative to natural selection acting alone. The long-term ramifications of such human-induced modifications to adaptive landscapes are currently unknown and certainly warrant further investigation.

Quantification of plasma sulfatides by mass spectrometry: Utility for metachromatic leukodystrophy.

Impaired sulfatide catabolism is the primary biochemical insult in patients with the inherited neurodegenerative disease, metachromatic leukodystrophy (MLD), and sulfatide elevation in body fluids is useful in the diagnostic setting. Here we used mass spectrometry to quantify fourteen species of sulfatide, in addition to the deacetylated derivative, lyso-sulfatide, using high pressure liquid chromatography-electrospray ionisation-tandem mass spectrometry in both positive and negative ion mode. A single phase extraction of 0.01 mL of MLD plasma identified all 14 sulfatide species in the positive ion mode but none in the negative ion mode. Interrogation of seven major and seven hydroxylated molecular species, as well as lyso-sulfatide, identified the C18 isoform as the most informative for MLD. The C18 produced a linear response and was below the limit of quantification (<10 pmol mL-1) in control plasma with concentrations in MLD plasma ranging from 12 to 196 pmol mL-1. Serial plasma samples from an MLD patient post-therapeutic bone marrow transplant proved similar to non-disease controls with C18 sulfatide concentrations below the limit of quantification, as did samples from three individuals with an arylsulfatase A pseudodeficiency - a population variant which appears deficient upon enzymatic assay, without manifestation of disease. These findings emphasise the utility of the C18 sulfatide species for the diagnosis of MLD and biochemical monitoring of MLD patients. Extension of this approach to a newborn screening card correctly identified an MLD patient at birth with elevated C18 sulfatide at levels almost double that present in the newborn card from his unaffected sibling, suggesting the methodology may have applicability for newborn screening.

Newborn screening for 3-methylcrotonyl-CoA carboxylase deficiency: population heterogeneity of MCCA and MCCB mutations and impact on risk assessment.

New technology enables expansion of newborn screening (NBS) of inborn errors aimed to prevent adverse outcome. In conditions with a large share of asymptomatic phenotypes, the potential harm created by NBS must carefully be weighed against benefit. Policies vary throughout the United States, Australia, and Europe due to limited data on outcome and treatability of candidate screening conditions. We elaborated the rationale for decision making in 3-methylcrotonyl-coenzyme A (CoA) carboxylase deficiency (MCCD), which afflicts leucine catabolism, with reported outcomes ranging from asymptomatic to death. In Bavaria, we screened 677,852 neonates for 25 conditions, including MCCD, based on elevated concentrations of 3-hydroxyisovalerylcarnitine (3-HIVA-C). Genotypes of MCCA (MCCC1) and MCCB (MCCC2) were assessed in identified newborns, their relatives, and in individuals (n = 17) from other regions, and correlated to biochemical and clinical phenotypes. NBS revealed eight newborns and six relatives with MCCD, suggesting a higher frequency than previously assumed (1:84,700). We found a strikingly heterogeneous spectrum of 22 novel and eight reported mutations. Allelic variants were neither related to biochemical nor anamnestic data of our probands showing all asymptomatic or benign phenotypes. Comparative analysis of case reports with NBS data implied that only few individuals (< 10%) develop symptoms. In addition, none of the symptoms reported so far can clearly be attributed to MCCD. MCCD is a genetic condition with low clinical expressivity and penetrance. It largely represents as nondisease. So far, there are no genetic or biochemical markers that would identify the few individuals potentially at risk for harmful clinical expression. The low ratio of benefit to harm was pivotal to the decision to exclude MCCD from NBS in Germany. MCCD may be regarded as exemplary of the ongoing controversy arising from the inclusion of potentially asymptomatic conditions, which generates a psychological burden for afflicted families and a financial burden for health care systems.

The ideal free pike: 50 years of fitness-maximizing dispersal in Windermere.

The ideal free distribution (IFD) theory is one of the most influential theories in evolutionary ecology. It predicts how animals ought to distribute themselves within a heterogeneous habitat in order to maximize lifetime fitness. We test the population level consequence of the IFD theory using 40-year worth data on pike (Esox lucius) living in a natural lake divided into two basins. We do so by employing empirically derived density-dependent survival, dispersal and fecundity functions in the estimation of basin-specific density-dependent fitness surfaces. The intersection of the fitness surfaces for the two basins is used for deriving expected spatial distributions of pike. Comparing the derived expected spatial distributions with 50 years data of the actual spatial distribution demonstrated that pike is ideal free distributed within the lake. In general, there was a net migration from the less productive north basin to the more productive south basin. However, a pike density-manipulation experiment imposing shifting pike density gradients between the two basins managed to switch the net migration direction and hence clearly demonstrated that the Windermere pike choose their habitat in an ideal free manner. Demonstration of ideal free habitat selection on an operational field scale like this has never been undertaken before.

Screening for lysosomal storage disorders--a clinical perspective.

The availability of therapies for lysosomal storage diseases (LSDs) and clear documentation from animal studies that optimal therapy depends on early diagnosis have set the scene for newborn screening for LSDs. The combined incidence of this group of conditions is approximately 1 in 7000, well within the feasible range for newborn screening programmes. The availability of multiplex technology has facilitated the technical aspects of initial screening. The scientific challenge is to predict disease severity early enough to influence choice of therapy. LSD screening is discussed from the point of view of the scientists, the families affected by these conditions, the community and clinicians.