Accurate detection of Alzheimer’s disease (AD) pathophysiological changes is crucial for research and clinical practice. While positron emission tomography (PET) imaging is an established reference standard for detecting brain amyloid and tau deposition, cerebrospinal fluid (CSF) biomarkers offer a more accessible alternative. This study aimed to identify optimal CSF biomarkers and thresholds for predicting tau and amyloid PET positivity in a memory clinic population. This cross-sectional, observational study included 220 participants from a memory clinic who underwent amyloid or tau PET scans and CSF biomarker analysis using either Fujirebio INNOTEST or LUMIPULSE assays. CSF biomarker performance was assessed via receiver operating characteristic (ROC) analysis. Double-threshold approaches were implemented to address classification uncertainty. Ratios combining biomarkers of both amyloid and tau, such as Aβ42/pTau, consistently outperformed individual biomarkers in detecting amyloid and tau PET positivity. For amyloid PET, the Aβ42/pTau ratio achieved an AUC of 0.93 (95

This retrospective study on X-linked PDHA1-related pyruvate dehydrogenase complex (PDHc) deficiency combined a systematic literature review with a multicentre survey exploring genotypes, phenotypes and survival. Data from 891 individuals (45% unpublished) were included. Of note, 53% of cases were females. Median age at last assessment was 6 years (range 0-80 years, n = 622). We detected 331 different (118 unpublished) PDHA1 variants, of which 75% (305/405) had occurred de novo. Variants in this study were uploaded to ClinVar (SCV006297015-SCV006297345). The 10 most frequent variants accounted for 36% of the diagnoses. Sixty-nine per cent of the variants were private; missense (50%) and frameshift (20%) variants were most common. Frameshift/nonsense (FS/N) variants in males (44/401, 11%) were confined to regions escaping nonsense-mediated decay (NMD) and were significantly less frequent than in females (151/461, 33%). Neonatal or infantile (405/529, 77%) presentations were most frequent, with pre/perinatal abnormalities reported in 47% (159/342). FS/N variants in the NMD-predicted region 3.9 [95% confidence interval (CI) 1.54-11.04] times increased the odds of fetal findings. Females presented significantly earlier [2 months, interquartile range (IQR) 7.0, n = 224] than males (8 months, IQR 16.6, n = 233), with increased risk of neonatal presentation [odds ratio (OR) 3.01 (95% CI 1.279-7.616)] when harbouring FS/N variants in the NMD-predicted region. The overall (n = 242) mean survival time was 10.9 (95% CI 9.9-11.9) years. On average, females survived 4.5 (95% CI 2.62-6.40) years longer than males despite presenting more severe phenotypes. Poor survival was associated with male sex [hazard ratio (HR) 3.3 (95% CI 1.95-5.62)], neonatal presentation [HR 5.5 (95% CI 2.17-14.09)], FS/N variants in the NMD-predicted region [HR 4.0 (95% CI 1.78, 9.16)] and splice variants [HR 2.3 (95% CI 1.15, 4.59)]. More severe clinical phenotypes were predicted by neonatal or infantile presentations and by female sex. Developmental delay (DD), intellectual disability (ID), muscle hypotonia, abnormal movements, seizures, feeding difficulties and microcephaly were the most frequent phenotypes, all occurring in more than half. Corpus callosum or basal ganglia alterations and cerebral atrophy were common. Four per cent (36/891) were reported to have mild phenotypes with no DD nor ID (25/36 males). This is the largest dataset on a nuclear-encoded defect of mitochondrial energy metabolism. The genotypic and phenotypic details further defines the disease landscape and can be used for variant interpretation. The correlations between genotypes, sex, phenotypes and survival, adds substantial improvement to counselling.

We report the case of a Syrian female refugee with late diagnosis of glutaric aciduria type 1 characterised by massive axial hypotonia and quadriplegia who only started adequate diet upon arrival in Switzerland at the age of 4 years, after a strenuous migration journey. Soon after arrival, she died from an unexpected severe upper cervical myelopathy, heralded by acute respiratory distress after a viral infection. This was likely due to repeated strains on her hypotonic neck and precipitated by an orthotopic os odontoideum who led to atlanto-axial subluxation. This case reminds us not to omit handling patients with insufficient postural control and hypotonia with great care to avoid progressive cervical myelopathy.

Advances in bioanalytical technologies such as high throughput sequencing have paved the way for an exponential increase in the discovery of inborn errors of metabolism (IEM), which now sum up to more than 1800 IEM. These powerful technologies play a decisive role in shortening the diagnostic odyssey of patients affected by rare diseases. Yet, their added value in guiding therapy is still limited. Metabolic medicine remains a growing discipline that is particularly dependent on specialized laboratory analyses and has adopted early on the fundamental concept of a patient-centered care approach. The discovery of phenylketonuria (PKU) as a treatable cause of mental retardation has hence led to the implementation of newborn screening. With this example, we highlight some key concepts in caring for patients affected by IEM.

Advances in bioanalytical technologies such as high throughput sequencing have paved the way for an exponential increase in the discovery of inborn errors of metabolism (IEM), which now sum up to more than 1800 IEM. These powerful technologies play a decisive role in shortening the diagnostic odyssey of patients affected by rare diseases. Yet, their added value in guiding therapy is still limited. Metabolic medicine remains a growing discipline that is particularly dependent on specialized laboratory analyses and has adopted early on the fundamental concept of a patient-centered care approach. The discovery of phenylketonuria (PKU) as a treatable cause of mental retardation has hence led to the implementation of newborn screening. With this example, we highlight some key concepts in caring for patients affected by IEM.Les avancées bio-analytiques, dont l’avènement du séquençage à haut débit, ont conduit à une augmentation exponentielle du nombre d’erreurs innées du métabolisme (EIM) recensées : plus de 1800 à ce jour. Ces technologies sont déterminantes pour remédier à l’errance diagnostique de patients souffrant de maladies rares. En comparaison, leur apport pour guider la pratique thérapeutique est secondaire. La médecine des maladies métaboliques, discipline jeune et particulièrement tributaire d’analyses de laboratoire spécialisées, intègre fondamentalement une approche personnalisée du patient. Ainsi, la découverte de la phénylcétonurie (PCU) et de son traitement est à l’origine du dépistage néonatal pour prévenir le handicap mental. À l’aide de cet exemple, nous illustrons quelques aspects clés de la prise en charge de patients porteurs d’EIM.

BackgroundThe key Alzheimer’s disease (AD) biomarkers are traditionally measured with techniques/exams that are either expensive (amyloid-positron emission tomography (PET) and tau-PET), invasive (cerebrospinal fluid Aβ42and p-tau181), or poorly specific (atrophy on MRI and hypometabolism on fluorodeoxyglucose-PET). Recently developed plasma biomarkers could significantly enhance the efficiency of the diagnostic pathway in memory clinics and improve patient care. This study aimed to: (1) confirm the correlations between plasma and traditional AD biomarkers, (2) assess the diagnostic accuracy of plasma biomarkers as compared with traditional biomarkers, and (3) estimate the proportion of traditional exams potentially saved thanks to the use of plasma biomarkers.MethodsParticipants were 200 patients with plasma biomarkers and at least one traditional biomarker collected within 12 months.ResultsOverall, plasma biomarkers significantly correlated with biomarkers assessed through traditional techniques: up tor=0.50 (p<0.001) among amyloid,r=0.43 (p=0.002) among tau, andr=−0.23 (p=0.001) among neurodegeneration biomarkers. Moreover, plasma biomarkers showed high accuracy in discriminating the biomarker status (normal or abnormal) determined by using traditional biomarkers: up to area under the curve (AUC)=0.87 for amyloid, AUC=0.82 for tau, and AUC=0.63 for neurodegeneration status. The use of plasma as a gateway to traditional biomarkers using cohort-specific thresholds (with 95% sensitivity and 95% specificity) could save up to 49% of amyloid, 38% of tau, and 16% of neurodegeneration biomarkers.ConclusionThe implementation of plasma biomarkers could save a remarkable proportion of more expensive traditional exams, making the diagnostic workup more cost-effective and improving patient care.

HIBCH and ECHS1 genes encode two enzymes implicated in the critical steps of valine catabolism, 3‐hydroxyisobutyryl‐coenzyme A (CoA) hydrolase (HIBCH) and short‐chainenoyl‐CoA hydratase (ECHS1), respectively. HIBCH deficiency (HIBCHD) and ECHS1 deficiency (ECHS1D) generate rare metabolic dysfunctions, often revealed by neurological symptoms. The aim of this study was to describe movement disorders spectrum in patients with pathogenic variants in ECHS1 and HIBC.

Objectives: Introduction SPATA5 is a newly reported cause of early-onset epileptic encephalopathy with typical characteristics, including hearing loss which was considered as a hallmark for this disorder.

Lipoprotein(a) [Lp(a)] is an LDL-like molecule that is likely causally related to cardiovascular events. Lp(a) levels are highly variable, by more two orders of magnitude, and most of this variability appears to be of genetic origin. Exogenous hormones (hormone replacement therapy) seem to influence Lp(a) levels, but the impact of the variation of endogenous hormone levels on Lp(a) is unknown. To investigate the association between Lp(a) levels and non-genetic factors, as endogenous steroid hormone levels, in contrast to genetic factors. We investigated the association of 28 endogenous steroids with Lp(a) levels and compared the association to other non-genetic and genetic variables in a prospective, population-based sample (N=1,021). The average age of the participants was 51 years and 53% were female. Median Lp(a) levels were 62 (±204) mg/l and the 90th and 99th percentile of Lp(a) was 616mg/l and 1035 mg/l respectively. The prevalence of a Lp(a) elevation ≥700mg/l was 3.2% and Lp(a) varied greatly from undetectable to 1,690mg/l. Age explained 2.0% of Lp(a) variability (p<0.001), 1% was explained by LDL levels (p=0.001), and 40% by two single nucleotide polymorphisms near the Lp(a) gene that have been previously described. Lp(a) levels were on average almost two times more elevated in secondary prevention and in individuals with very elevated LDL levels (≥4.9 mmol/l). Of the 28 endogenous steroid hormones assessed, 5-androstene-3b,16α,17β-triol, androsterone, 16α-hydroxy DHEA, and estriol were nominatively associated with serum Lp(a) levels and explained 0.4–1% of Lp(a) variability in univariate analyses, but they did not reach significance in multi-variate models. Our results confirm previous findings demonstrating that the majority of the Lp(a) variation in the general population is of genetic origin. Age and LDL-levels explain a further small part of Lp(a) variability. Endogenous hormone levels do not contribute significantly to the wide range of variability. Type of funding sources: None. Coefficient plot Lp(a) and variables

BACKGROUND:Lipoprotein(a) [Lp(a)] is an LDL-like molecule that is likely causal for cardiovascular events and Lp(a) variability has been shown to be mostly of genetic origin. Exogenous hormones (hormone replacement therapy) seem to influence Lp(a) levels, but the impact of endogenous hormone levels on Lp(a) is still unknown. The aim of the study was to assess the effect of endogenous steroid hormone metabolites on Lp(a).METHODS:Lipoprotein(a) levels were measured in 1,021 participants from the Swiss Kidney Project on Genes in Hypertension, a family-based, multicentre, population-based prospective cohort study. Endogenous levels of 28 steroid hormone precursors were measured in 24-h urine collections from 883 individuals. Of the participants with Lp(a) data, 1,011 participants had also genotypes available.RESULTS:The participants had an average age of 51 years and 53% were female. Median Lp(a) levels were 62 mg/L, and the 90th percentile was 616 mg/L. The prevalence of a Lp(a) elevation ≥700 mg/L was 3.2%. Forty-three per cent of Lp(a) variability was explained respectively by: age (2%, p < .001), LDL-C (1%, p = .001), and two SNPs (39%, p value<2⋅10-16 ). Of the 28 endogenous steroid hormones assessed, androstenetriol, androsterone, 16α-OH-DHEA and estriol were nominatively associated with serum Lp(a) levels in univariable analyses and explained 0.4%-1% of Lp(a) variability, but none of them reached significance in multivariable models.CONCLUSIONS:In this contemporary population-based study, the prevalence of a Lp(a) elevation ≥700 mg/L was 3.2%. The effect of endogenous steroid hormone levels of Lp(a) variability was small at best, suggesting a negligible impact on the wide range of Lp(a) variability.

In a consanguineous Pakistani family with two affected individuals, a homozygous variant Gly399Val in the eighth transmembrane domain of the taurine transporter SLC6A6 was identified resulting in a hypomorph transporting capacity of ~15% compared with normal. Three-dimensional modeling of this variant has indicated that it likely causes displacement of the Tyr138 (TM3) side chain, important for transport of taurine. The affected individuals presented with rapidly progressive childhood retinal degeneration, cardiomyopathy and almost undetectable plasma taurine levels. Oral taurine supplementation of 100 mg/kg/day resulted in maintenance of normal blood taurine levels. Following approval by the ethics committee, a long-term supplementation treatment was introduced. Remarkably, after 24-months, the cardiomyopathy was corrected in both affected siblings, and in the 6-years-old, the retinal degeneration was arrested, and the vision was clinically improved. Similar therapeutic approaches could be employed in Mendelian phenotypes caused by the dysfunction of the hundreds of other molecular transporters.

More than 200 Pakistani consanguineous families with multiple individuals having recessive visual impairments were evaluated by exome sequencing and genotyping. One of the families, F315, from the Kohat region of Pakistan contained 2 affected individuals with a homozygous deleterious variant Gly399Val (NM_003043.5:c.1196G>T) in the taurine transporter SLC6A6 (MIM:186854) which segregated with the phenotype of progressive retinal degeneration. Gly399 is highly conserved in vertebrates and molecular modeling suggests that the increased bulk of the valine substitution displaces Tyr138 which participates in substrate coordination and transport and is consistent with the hypomorphic variant exhibiting only ~15% of the transport capacity of the native protein as determined by taurine uptake analyses in HEK‐293 cells transiently or stably expressing SLC6A6 or the Gly399Val variant. The reduced function was attributed to a catalytic effect rather than plasma membrane levels and analysis of patient‐derived fibroblasts of affected individuals mirrored these findings. Affected individuals exhibited cone‐rod retinopathy and cardiomyopathy and remarkably taurine supplementation for 24 months resulted in resolution of the cardiomyopathy and clinical stabilization of the retinopathy.Support or Funding InformationProVisu foundation and ERC grant 219968 to S.E.A., and NIH grant DA027845 to L.K.H.

BACKGROUND:Minimal lipoprotein(a) [Lp(a)] target values are advocated for high-risk cardiovascular patients. We investigated the prognostic value of Lp(a) in the acute setting of patients with acute coronary syndromes (ACS). MATERIALS AND METHODS:Plasma levels of Lp(a) were collected at time of angiography from 1711 patients hospitalized for ACS in a multicentre Swiss prospective cohort. Associations between elevated Lp(a) ≥30 mg/dL (cut-off corresponding to the 75th percentile of the assay) or Lp(a) tertiles at baseline, and major adverse cardiovascular events (MACE) at 1 year, defined as a composite of cardiac death, myocardial infarction or stroke, were assessed using hazard ratios (HR) and 95% confidence intervals (CI) adjusting for traditional cardiovascular risk factors (age, sex, smoking, diabetes, hypertension, low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C] and triglycerides. RESULTS:Lp(a) levels range between 2.5 and 132 mg/dL with a median value of 6 mg/dL and a mean value of 14.2 mg/dL. A total of 276 patients (23.0%) had Lp(a) plasma levels ≥30 mg/dL. Patients with elevated Lp(a) were more likely to be of female gender and to have higher levels of total cholesterol, LDL-C, HDL-C and triglycerides. Higher Lp(a) was associated with failure to reach the LDL-C target <1.8 mmol/L at 1 year (HR 1.71, 95% CI 1.13-2.58, P = 0.01). No association was found between elevated Lp(a) and MACE at 1 year (HR 1.05, 95% CI 0.64-1.73), nor for Lp(a) tertiles (HR 0.82, 95% CI 0.52-1.28, P > 0.20) or standardized continuous variables (0.98, 95% CI 0.82-1.19 for each increase of standard deviation). CONCLUSIONS:Our real-world data suggest high Lp(a) levels at time of angiography are not predictive for cardiovascular outcomes in patients otherwise medically well controlled, but might be useful to identify patients who would not be on LDL-C targets 1 year after ACS.