Genetic Background of Blood β-Hydroxybutyrate Acid Concentrations in Early-Lactating Holstein Dairy Cows Based on Genome-Wide Association Analyses

Ketosis is a common metabolic disorder in the early lactation of dairy cows. It is typically diagnosed by measuring the concentration of β-hydroxybutyrate (BHB) in the blood. This study aimed to estimate the genetic parameters of blood BHB and conducted a genome-wide association study (GWAS) based on the estimated breeding value. Phenotypic data were collected from December 2019 to August 2023, comprising blood BHB concentrations in 45,617 Holstein cows during the three weeks post-calving across seven dairy farms. Genotypic data were obtained using the Neogen Geneseek Genomic Profiler (GGP) Bovine 100 K SNP Chip and GGP Bovine SNP50 v3 (Illumina Inc., San Diego, CA, USA) for genotyping. The estimated heritability and repeatability values for blood BHB levels were 0.167 and 0.175, respectively. The GWAS result detected a total of ten genome-wide significant associations with blood BHB. Significant SNPs were distributed in Bos taurus autosomes (BTA) 2, 6, 9, 11, 13, and 23, with 48 annotated candidate genes. These potential genes included those associated with insulin regulation, such as INSIG2, and those linked to fatty acid metabolism, such as HADHB, HADHA, and PANK2. Enrichment analysis of the candidate genes for blood BHB revealed the molecular functions and biological processes involved in fatty acid and lipid metabolism in dairy cattle. The identification of novel genomic regions in this study contributes to the characterization of key genes and pathways that elucidate susceptibility to ketosis in dairy cattle.

Gene association analysis of an osteopontin polymorphism and ketosis resistance in dairy cattle

The aim of this study was to identify the c.495C > T polymorphism within exon 1 of the osteopontin gene (OPN), and to analyze its association with susceptibility to ketosis in Polish Holstein-Friesian (HF) cows. The study utilized blood samples from 977 HF cows, for the determination of β-hydroxybutyric acid (BHB) and for DNA isolation. The c.495C > T polymorphism of the bovine osteopontin gene was determined by PCR-RFLP. The CT genotype (0.50) was deemed the most common, while TT (0.08) was the rarest genotype. Cows with ketosis most often had the CC genotype, while cows with the TT genotype had the lowest incidence of ketosis. To confirm the relationship between the genotype and ketosis in cows, a weight of evidence (WoE) was generated. A very strong effect of the TT genotype on resistance to ketosis was demonstrated. The distribution of the ROC curve shows that the probability of resistance to ketosis is > 75% if cows have the TT genotype of the OPN gene (cutoff value is 0.758). Results suggest that TT genotype at the c.495C > T locus of the OPN gene might be effective way to detect the cows with risk of ketosis.

A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes

Hyperhomocysteneinemia (HHcy) is common in the general population and is a risk factor for atherosclerosis by mechanisms that are still elusive. A hypomethylated status of epigenetically relevant targets may contribute to the vascular toxicity associated with HHcy. Ketogenic diets (KD) are diets with a severely restricted amount of carbohydrates that are being widely used, mainly for weight-loss purposes. However, studies associating nutritional ketosis and HHcy are lacking. This pilot study investigates the effects of mild HHcy induced by nutritional manipulation of the methionine metabolism in the absence of dietary carbohydrates on disease progression and specific epigenetic changes in the apolipoprotein-E deficient (apoE^-/-) mouse model. ApoE^-/- mice were either fed a KD, a diet with the same macronutrient composition but low in methyl donors (low methyl KD, LMKD), or control diet. After 4, 8 or 12 weeks plasma was collected for the quantification of: (1) nutritional ketosis, (i.e., the ketone body beta-hydroxybutyrate using a colorimetric assay); (2) homocysteine by HPLC; (3) the methylating potential S-adenosylmethionine to S-adenosylhomocysteine ratio (AdoHcy/AdoMet) by LC-MS/MS; and (4) the inflammatory cytokine monocyte chemoattractant protein 1 (MCP1) by ELISA. After 12 weeks, aortas were collected to assess: (1) the vascular AdoHcy/AdoMet ratio; (2) the volume of atherosclerotic lesions by high-field magnetic resonance imaging (14T-MRI); and (3) the content of specific epigenetic tags (H3K27me3 and H3K27ac) by immunofluorescence. The results confirmed the presence of nutritional ketosis in KD and LMKD mice but not in the control mice. As expected, mild HHcy was only detected in the LMKD-fed mice. Significantly decreased MCP1 plasma levels and plaque burden were observed in control mice versus the other two groups, together with an increased content of one of the investigated epigenetic tags (H3K27me3) but not of the other (H3K27ac). Moreover, we are unable to detect any significant differences at the p < 0.05 level for MCP1 plasma levels, vascular AdoMet:AdoHcy ratio levels, plaque burden, and specific epigenetic content between the latter two groups. Nevertheless, the systemic methylating index was significantly decreased in LMKD mice versus the other two groups, reinforcing the possibility that the levels of accumulated homocysteine were insufficient to affect vascular transmethylation reactions. Further studies addressing nutritional ketosis in the presence of mild HHcy should use a higher number of animals and are warranted to confirm these preliminary observations.

Association of Agenesis of the Dorsal Pancreas With HNF1B Heterozygote Mutation: A Case Report

BACKGROUND

Agenesis of the dorsal pancreas (ADP) is a rare disease, the pathogenic mechanism of which is partially related to variants of hepatocyte nuclear factor 1B (HNF1B) gene.

CASE PRESENTATION

We report a case of ADP, which presented with acute ketoacidosis, hyperuricemia, and liver dysfunction. In this case, the HNF1B score was estimated as 16 and a heterozygous variant of HNF1B in exon 2 (c.513G>A-p.W171X) was identified through gene sequencing.

CONCLUSIONS

A good understanding of the clinical comorbidities of ADP is essential for avoiding missed diagnosis to a great extent. Moreover, estimation of HNF1B score is recommended before genetic testing.

Effect of functional single nucleotide polymorphism g.-572 A > G of apolipoprotein A1 gene on resistance to ketosis in Chinese Holstein cows

The ketosis has negative effects on the high-yielding dairy cows during early lactation. Apolipoprotein A1 (APOA1) is a component of high-density lipoprotein. However, the association of APOA1 gene with ketosis, and the molecular mechanisms of expression of APOA1 gene are not fully understood in dairy cows. In this study, expression of APOA1 in the liver and blood was investigated by RT-qPCR and immunohistochemistry, and genetic variation in the 5'-flanking region of the AOPA1 gene was also screened and identified. In addition, correlation of the single nucleotide polymorphisms (SNPs) of APOA1 gene with blood ketone characters, and activity of APOA1 promoter were analyzed in dairy cows. The results showed that ApoA1 protein was expressed in the liver, and the mRNA level of APOA1 was significantly higher in the cows with ketosis comparing to the healthy cows. In addition, a novel SNP (g.-572 A > G) in the core promoter of the APOA1 gene was identified between base g.-714 and g.-68 through transient transfection in both HepG2 cell and FFb cell, and luciferase report assay. Moreover, there was lower concentration of blood β-hydroxybutyrate in cows with genotype GG comparing to the cows with genotypes AA and AG. This study reported for the first time that the genetic variant g.-572 A > G in the core promoter region of APOA1 gene was associated with the ketosis in Chinese Holstein cows, and g.-572 A > G may be used as a genetic marker for ketosis prevention.

The neuroimaging findings of monocarboxylate transporter 1 deficiency

Monocarboxylate transporter 1 (MCT1) deficiency was first described in 2014 by Hasselt et al. as a novel genetic cause of recurrent ketoacidosis. Patients present in the first year of life with acute episodes of ketoacidosis triggered by fasting or infections. Patients with homozygous mutations are known to have a more severe phenotype with mild to moderate developmental delay and an increased prevalence of epilepsy. There is only one recent report of the neuroimaging findings of this disorder as reported by Al-Khawaga et al. (Front Pediatr. 7:299, 2019). We report the neuroimaging abnormalities in two siblings with similar clinical presentation of recurrent ketoacidosis, seizures, and developmental delay. Whole exome sequencing in the younger sibling confirmed a known pathogenic homozygous mutation in MCT1, also known as SLC16A1 gene. Brain MRI showed a similar very distinctive pattern of signal abnormality at the gray-white matter junction, basal ganglia, and thalami in both patients. Both siblings had agenesis of the corpus callosum. Knowledge of this pattern of brain involvement might contribute to an earlier diagnosis and timely management of this rare and under recognized disorder.

Modulation of Cellular Biochemistry, Epigenetics and Metabolomics by Ketone Bodies. Implications of the Ketogenic Diet in the Physiology of the Organism and Pathological States

Ketone bodies (KBs), comprising β-hydroxybutyrate, acetoacetate and acetone, are a set of fuel molecules serving as an alternative energy source to glucose. KBs are mainly produced by the liver from fatty acids during periods of fasting, and prolonged or intense physical activity. In diabetes, mainly type-1, ketoacidosis is the pathological response to glucose malabsorption. Endogenous production of ketone bodies is promoted by consumption of a ketogenic diet (KD), a diet virtually devoid of carbohydrates. Despite its recently widespread use, the systemic impact of KD is only partially understood, and ranges from physiologically beneficial outcomes in particular circumstances to potentially harmful effects. Here, we firstly review ketone body metabolism and molecular signaling, to then link the understanding of ketone bodies’ biochemistry to controversies regarding their putative or proven medical benefits. We overview the physiological consequences of ketone bodies’ consumption, focusing on (i) KB-induced histone post-translational modifications, particularly β-hydroxybutyrylation and acetylation, which appears to be the core epigenetic mechanisms of activity of β-hydroxybutyrate to modulate inflammation; (ii) inflammatory responses to a KD; (iii) proven benefits of the KD in the context of neuronal disease and cancer; and (iv) consequences of the KD’s application on cardiovascular health and on physical performance.

Sequence variants associating with urinary biomarkers

Urine dipstick tests are widely used in routine medical care to diagnose kidney and urinary tract and metabolic diseases. Several environmental factors are known to affect the test results, whereas the effects of genetic diversity are largely unknown. We tested 32.5 million sequence variants for association with urinary biomarkers in a set of 150 274 Icelanders with urine dipstick measurements. We detected 20 association signals, of which 14 are novel, associating with at least one of five clinical entities defined by the urine dipstick: glucosuria, ketonuria, proteinuria, hematuria and urine pH. These include three independent glucosuria variants at SLC5A2, the gene encoding the sodium-dependent glucose transporter (SGLT2), a protein targeted pharmacologically to increase urinary glucose excretion in the treatment of diabetes. Two variants associating with proteinuria are in LRP2 and CUBN, encoding the co-transporters megalin and cubilin, respectively, that mediate proximal tubule protein uptake. One of the hematuria-associated variants is a rare, previously unreported 2.5 kb exonic deletion in COL4A3. Of the four signals associated with urine pH, we note that the pH-increasing alleles of two variants (POU2AF1, WDR72) associate significantly with increased risk of kidney stones. Our results reveal that genetic factors affect variability in urinary biomarkers, in both a disease dependent and independent context.

Label-Free Quantitative Proteomics in a Methylmalonyl-CoA Mutase-Silenced Neuroblastoma Cell Line

Methylmalonic acidemias (MMAs) are inborn errors of metabolism due to the deficient activity of methylmalonyl-CoA mutase (MUT). MUT catalyzes the formation of succinyl-CoA from methylmalonyl-CoA, produced from propionyl-CoA catabolism and derived from odd chain fatty acids β-oxidation, cholesterol, and branched-chain amino acids degradation. Increased methylmalonyl-CoA levels allow for the presymptomatic diagnosis of the disease, even though no approved therapies exist. MMA patients show hyperammonemia, ketoacidosis, lethargy, respiratory distress, cognitive impairment, and hepatomegaly. The long-term consequences concern neurologic damage and terminal kidney failure, with little chance of survival. The cellular pathways affected by MUT deficiency were investigated using a quantitative proteomics approach on a cellular model of MUT knockdown. Currently, a consistent reduction of the MUT protein expression was obtained in the neuroblastoma cell line (SH-SY5Y) by using small-interfering RNA (siRNA) directed against an MUT transcript (MUT siRNA). The MUT absence did not affect the cell viability and apoptotic process in SH-SY5Y. In the present study, we evaluate and quantify the alterations in the protein expression profile as a consequence of MUT-silencing by a mass spectrometry-based label-free quantitative analysis, using two different quantitative strategies. Both quantitative methods allowed us to observe that the expression of the proteins involved in mitochondrial oxido-reductive homeostasis balance was affected by MUT deficiency. The alterated functional mitochondrial activity was observed in siRNA_MUT cells cultured with a propionate-supplemented medium. Finally, alterations in the levels of proteins involved in the metabolic pathways, like carbohydrate metabolism and lipid metabolism, were found.

Heterozygous carriers of succinyl-CoA:3-oxoacid CoA transferase deficiency can develop severe ketoacidosis

Succinyl-CoA:3-oxoacid CoA transferase (SCOT, gene symbol OXCT1) deficiency is an autosomal recessive disorder in ketone body utilization that results in severe recurrent ketoacidotic episodes in infancy, including neonatal periods. More than 30 patients with this disorder have been reported and to our knowledge, their heterozygous parents and siblings have had no apparent ketoacidotic episodes. Over 5 years (2008-2012), we investigated several patients that presented with severe ketoacidosis and identified a heterozygous OXCT1 mutation in four of these cases (Case1 p.R281C, Case2 p.T435N, Case3 p.W213*, Case4 c.493delG). To confirm their heterozygous state, we performed a multiplex ligation-dependent probe amplification analysis on the OXCT1 gene which excluded the presence of large deletions or insertions in another allele. A sequencing analysis of subcloned full-length SCOT cDNA showed that wild-type cDNA clones were present at reasonable rates to mutant cDNA clones. Over the following 2 years (2013-2014), we analyzed OXCT1 mutations in six more patients presenting with severe ketoacidosis (blood pH ≦7.25 and total ketone body ≧10 mmol/L) with non-specific urinary organic acid profiles. Of these, a heterozygous OXCT1 mutation was found in two cases (Case5 p.G391D, Case6 p.R281C). Moreover, transient expression analysis revealed R281C and T435N mutants to be temperature-sensitive. This characteristic may be important because most patients developed ketoacidosis during infections. Our data indicate that heterozygous carriers of OXCT1 mutations can develop severe ketoacidotic episodes in conjunction with ketogenic stresses.

FGF21 is not required for glucose homeostasis, ketosis or tumour suppression associated with ketogenic diets in mice

AIMS/HYPOTHESIS

Ketogenic diets (KDs) have increasingly gained attention as effective means for weight loss and potential adjunctive treatment of cancer. The metabolic benefits of KDs are regularly ascribed to enhanced hepatic secretion of fibroblast growth factor 21 (FGF21) and its systemic effects on fatty-acid oxidation, energy expenditure (EE) and body weight. Ambiguous data from Fgf21-knockout animal strains and low FGF21 concentrations reported in humans with ketosis have nevertheless cast doubt regarding the endogenous function of FGF21. We here aimed to elucidate the causal role of FGF21 in mediating the therapeutic benefits of KDs on metabolism and cancer.

METHODS

We established a dietary model of increased vs decreased FGF21 by feeding C57BL/6J mice with KDs, either depleted of protein or enriched with protein. We furthermore used wild-type and Fgf21-knockout mice that were subjected to the respective diets, and monitored energy and glucose homeostasis as well as tumour growth after transplantation of Lewis lung carcinoma cells.

RESULTS

Hepatic and circulating, but not adipose tissue, FGF21 levels were profoundly increased by protein starvation, independent of the state of ketosis. We demonstrate that endogenous FGF21 is not essential for the maintenance of normoglycaemia upon protein and carbohydrate starvation and is therefore not needed for the effects of KDs on EE. Furthermore, the tumour-suppressing effects of KDs were independent of FGF21 and, rather, driven by concomitant protein and carbohydrate starvation.

CONCLUSIONS/INTERPRETATION

Our data indicate that the multiple systemic effects of KD exposure in mice, previously ascribed to increased FGF21 secretion, are rather a consequence of protein malnutrition.

Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: urinary organic acid profiles and expanded spectrum of mutations

Mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase (HMCS2) deficiency results in episodes of hypoglycemia and increases in fatty acid metabolites. Metabolite abnormalities described to date in HMCS2 deficiency are nonspecific and overlap with other inborn errors of metabolism, making the biochemical diagnosis of HMCS2 deficiency difficult. Urinary organic acid profiles from periods of metabolic decompensation were studied in detail in HMCS2-deficient patients from four families. An additional six unrelated patients were identified from clinical presentation and/or qualitative identification of abnormal organic acids. The diagnosis was confirmed by sequencing and deletion/duplication analysis of the HMGCS2 gene. Seven related novel organic acids were identified in urine profiles. Five of them (3,5-dihydroxyhexanoic 1,5 lactone; trans-5-hydroxyhex-2-enoate; 4-hydroxy-6-methyl-2-pyrone; 5-hydroxy-3-ketohexanoate; 3,5-dihydroxyhexanoate) were identified by comparison with synthesized or commercial authentic compounds. We provisionally identified trans-3-hydroxyhex-4-enoate and 3-hydroxy-5-ketohexanoate by their mass spectral characteristics. These metabolites were found in samples taken during periods of decompensation and normalized when patients recovered. When cutoffs of adipic >200 and 4-hydroxy-6-methyl-2-pyrone >20 μmol/mmol creatinine were applied, all eight samples taken from five HMCS2-deficient patients during episodes of decompensation were flagged with a positive predictive value of 80% (95% confidence interval 35-100%). Some ketotic patients had increased 4-hydroxy-6-methyl-2-pyrone. Molecular studies identified a total of 12 novel mutations, including a large deletion of HMGCS2 exon 1 in two families, highlighting the need to perform quantitative gene analyses. There are now 26 known HMGCS2 mutations, which are reviewed in the text. 4-Hydroxy-6-methyl-2-pyrone and related metabolites are markers for HMCS2 deficiency. Detection of these metabolites will streamline the biochemical diagnosis of this disorder.

Evaluation of glycogen storage disease as a cause of ketotic hypoglycemia in children

INTRODUCTION

Ketone formation is a normal response when hypoglycemia occurs. Since the majority of children with recurrent hypoglycemia cannot be diagnosed with a known endocrine or metabolic disorder on a critical sample, ketotic hypoglycemia has been described as the most common cause of low blood glucose concentrations in children. Critical samples, however, will miss the ketotic forms of glycogen storage disease (GSD), which present with elevated ketones, hypoglycemia, and normal hormonal concentrations.

RESULTS

A total of 164 children (96 boys, 68 girls) were enrolled in the study. Prediction of pathogenicity of DNA changes using computer modeling confirmed pathology in 20 individuals [four GSD 0, two GSD VI, 12 GSD IX alpha, one GSD IX beta, one GSD IX gamma] (12%). Boys were most likely to have changes in the PHKA2 gene, consistent with GSD IX alpha, an X-linked disorder.

CONCLUSIONS

Mutations in genes involved in glycogen synthesis and degradation were commonly found in children with idiopathic ketotic hypoglycemia. GSD IX is likely an unappreciated cause of ketotic hypoglycemia in children, while GSD 0 and VI are relatively uncommon. GSD IX alpha should particularly be considered in boys with unexplained hypoglycemia.

Association of HLA class II markers with autoantibody-negative ketosis-prone atypical diabetes compared to type 2 diabetes in a population of sub-Saharan African patients

AIM

We investigated the association of HLA DRB1 and DQB1 alleles, haplotypes and genotypes with unprovoked antibody-negative ketosis-prone atypical diabetes (A(-) KPD) in comparison to type 2 diabetes (T2D).

METHODS

A(-) KPD and T2D sub-Saharan African patients aged 19-63 years were consecutively recruited. Patients positive for cytoplasmic islet cell, insulin, glutamic acid decarboxylase or islet antigen-2 autoantibodies were excluded. Odds ratios were obtained via logistic regression after considering alleles with a minimum frequency of 5% in the study population. Bonferroni correction was used in the case of multiple comparisons.

RESULTS

Among the 130 participants, 35 (27%) were women and 57 (44%) were A(-) KPD. DRB1 and DQB1 allele frequencies were similar for both A(-) KPD and T2D patients; they did not confer any substantial risk even after considering type 1 diabetes susceptibility and resistance alleles. We found no association between A(-) KPD and the derived DRB1*07-DQB1*02:02 (OR: 0.55 [95%CI: 0.17-1.85], P=0.336); DRB1*11-DQB1*03:01 (OR: 2.42 [95%CI: 0.79-7.42], P=0.123); DRB1*15-DQB1*06:02 (OR: 0.87 [95%CI: 0.39-1.95], P=0.731) and DRB1*03:01-DQB1*02:01 (OR: 1.48 [95%CI: 0.55-3.96], P=0.437) haplotypes. Overall, we did not find any evidence of susceptibility to ketosis associated with DRB1 and DQB1 genotypes (all P>0.05) in A(-) KPD compared to T2D. Similar results were obtained after adjusting the analysis for age and sex.

CONCLUSION

Factors other than DRB1 and DQB1 genotype could explain the propensity to ketosis in A(-) KPD. These results need to be confirmed in a larger population with the perspective of improving the classification and understanding of the pathophysiology of A(-) KPD.

Monocarboxylate transporter 1 deficiency and ketone utilization

Ketoacidosis is a potentially lethal condition caused by the imbalance between hepatic production and extrahepatic utilization of ketone bodies. We performed exome sequencing in a patient with recurrent, severe ketoacidosis and identified a homozygous frameshift mutation in the gene encoding monocarboxylate transporter 1 (SLC16A1, also called MCT1). Genetic analysis in 96 patients suspected of having ketolytic defects yielded seven additional inactivating mutations in MCT1, both homozygous and heterozygous. Mutational status was found to be correlated with ketoacidosis severity, MCT1 protein levels, and transport capacity. Thus, MCT1 deficiency is a novel cause of profound ketoacidosis; the present work suggests that MCT1-mediated ketone-body transport is needed to maintain acid-base balance.

A novel activating ABCC8 mutation underlying neonatal diabetes mellitus in an infant presenting with cerebral sinovenous thrombosis

Neonatal diabetes mellitus is a rare clinical condition, which develops most commonly secondary to mutations in KCNJ11 and ABCC8 genes encoding ATP-sensitive K+ channels. Patients are typically diagnosed with hyperglycemia-related symptoms in the first 6 months of life and rarely with ketoacidosis. In this article, we report an infant who presented with focal clonic convulsion and thereafter was diagnosed with neonatal diabetes mellitus and thrombi in cerebral venous sinus. In this patient, after a molecular analysis of the ABCC8 gene revealed a novel heterozygous missense mutation (p.D424V), a successful transition from insulin to sulfonylurea treatment was made.

[Assessment of the natural history and clinical presentation of acetonemic vomiting]

INTRODUCTION

Ketosis in children may result from physiological adaptation to situations like fasting, fat-rich diet, straining physical activity, as well as from serious endocrine or metabolic disorders. The most frequently diagnosed cause of ketoacidosis are states of acetonemia and acetonuria with vomiting, during airways infections.

GOAL

Assessment of the natural history and clinical presentation of acetonemic vomiting in children.

PATIENTS AND METHODS

85 children from 18 months to 12 years of age with acetonemic vomiting were incorporated in this study. Detailed anamnesis, clinical examination, and chosen laboratory parameters were analyzed.

RESULTS

In 18% of the children a familial pattern of the disease was observed, 75% of the parents declared that their children had fat-rich meals on a regular basis, in 47% there was a tendency to recurrent respiratory tract. The most frequently observed symptoms were incoercible vomiting with nausea (100%), abdominal pain (87%), headaches (35%) and febrile states (62%). Ketosis triggers were: infections with insufficient fluid and food intake (68%), and child overfeeding with fat-rich products (23%). Observed biochemical disturbances were ketosis (mean J3-hydroxybutyric acid serum concentration--1.03 mmol/l, SD +/- 0.83), acetonuria, hypoglycemia (15%), metabolic acidosis (17%) and dyselectrolytemia (14%). The treatment of the children consisted in intravenous and oral rehydration, managing acid-base and electrolyte disturbances.

CONCLUSION

In some children acetonemic vomiting is recurrent, and thus prophylactic management is im- portant in children who are at risk.

A neonatal-onset succinyl-CoA:3-ketoacid CoA transferase (SCOT)-deficient patient with T435N and c.658-666dupAACGTGATT p.N220_I222dup mutations in the OXCT1 gene

Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency causes episodic ketoacidotic crises and no apparent symptoms between them. Here, we report a Japanese case of neonatal-onset SCOT deficiency. The male patient presented a severe ketoacidotic crisis, with blood pH of 7.072 and bicarbonate of 5.8 mmol/L at the age of 2 days and was successfully treated with intravenous infusion of glucose and sodium bicarbonate. He was diagnosed as SCOT deficient by enzymatic assay and mutation analysis. At the age of 7 months, he developed a second ketoacidotic crisis, with blood pH of 7.059, bicarbonate of 5.4 mmol/L, and total ketone bodies of 29.1 mmol/L. He experienced two milder ketoacidotic crises at the ages of 1 year and 7 months and 3 years and 7 months. His urinary ketone bodies usually range from negative to 1+ but sometimes show 3+ (ketostix) without any symptoms. Hence, this patient does not show permanent ketonuria, which is characteristic of typical SCOT-deficient patients. He is a compound heterozygote of c.1304C > A (T435N) and c.658-666dupAACGTGATT p.N220_I222dup. mutations in the OXCT1 gene. The T435N mutation was previously reported as one which retained significant residual activity. The latter novel mutation was revealed to retain no residual activity by transient expression analysis. Both T435N and N220_I222 lie close to the SCOT dimerization interface and are not directly connected to the active site in the tertiary structure of a human SCOT dimer. In transient expression analysis, no apparent interallelic complementation or dominant negative effects were observed. Significant residual activity from the T435N mutant allele may prevent the patient from developing permanent ketonuria.

Fibroblast growth factor 21-deficient mice demonstrate impaired adaptation to ketosis

Fibroblast growth factor 21 (FGF21) is a key metabolic regulator. Expressed primarily in liver and adipose tissue, FGF21 is induced via peroxisome proliferator-activated receptor (PPAR) pathways during states requiring increased fatty acid oxidation including fasting and consumption of a ketogenic diet. To test the hypothesis that FGF21 is a physiological regulator that plays a role in lipid oxidation, we generated mice with targeted disruption of the Fgf21 locus (FGF21 knockout). Mice lacking FGF21 had mild weight gain and slightly impaired glucose homeostasis, indicating a role in long-term energy homeostasis. Furthermore, FGF21KO mice tolerated a 24-h fast, indicating that FGF21 is not essential in the early stages of starvation. In contrast to wild-type animals in which feeding KD leads to dramatic weight loss, FGF21KO mice fed KD gained weight, developed hepatosteatosis, and showed marked impairments in ketogenesis and glucose control. This confirms the physiological importance of FGF21 in the adaptation to KD feeding. At a molecular level, these effects were accompanied by lower levels of expression of PGC1alpha and PGC1beta in FGF21KO mice, strongly implicating these key transcriptional regulators in the action of FGF21. Furthermore, within the liver, the maturation of the lipogenic transcription factor sterol regulatory element-binding protein-1c was increased in FGF21KO mice, implicating posttranscriptional events in the maladaptation of FGF21KO mice to KD. These data reinforce the role of FGF21 is a critical regulator of long-term energy balance and metabolism. Mice lacking FGF21 cannot respond appropriately to a ketogenic diet, resulting in an impaired ability to mobilize and utilize lipids.

A high-fat, ketogenic diet induces a unique metabolic state in mice

Ketogenic diets have been used as an approach to weight loss on the basis of the theoretical advantage of a low-carbohydrate, high-fat diet. To evaluate the physiological and metabolic effects of such diets on weight we studied mice consuming a very-low-carbohydrate, ketogenic diet (KD). This diet had profound effects on energy balance and gene expression. C57BL/6 mice animals were fed one of four diets: KD; a commonly used obesogenic high-fat, high-sucrose diet (HF); 66% caloric restriction (CR); and control chow (C). Mice on KD ate the same calories as mice on C and HF, but weight dropped and stabilized at 85% initial weight, similar to CR. This was consistent with increased energy expenditure seen in animals fed KD vs. those on C and CR. Microarray analysis of liver showed a unique pattern of gene expression in KD, with increased expression of genes in fatty acid oxidation pathways and reduction in lipid synthesis pathways. Animals made obese on HF and transitioned to KD lost all excess body weight, improved glucose tolerance, and increased energy expenditure. Analysis of key genes showed similar changes as those seen in lean animals placed directly on KD. Additionally, AMP kinase activity was increased, with a corresponding decrease in ACC activity. These data indicate that KD induces a unique metabolic state congruous with weight loss.

Selection Responses for Disease Resistance in Two Selection Experiments with Norwegian Red Cows

Genetic trends for clinical mastitis (CM), ketosis (KET), retained placenta (RP), and 305-d protein yield (PY305) were calculated for 2 Norwegian dairy cattle selection experiments. The first experiment, accomplished from 1978 to 1989, included groups selected for high (HMP) and low milk production (LMP). The second experiment started in 1989 and included selection for high protein yield (HPY) and low mastitis frequency (LCM). In both experiments proven sires from the active breeding program of Norwegian Red were used as sires. To take into account that selection of sires was external to the experiment, all available data from the Norwegian Red population, including disease records for 2.7 million first-lactation cows, were analyzed with a multivariate animal model. Estimated breeding values for cows in the experiments were extracted from this analysis to calculate genetic trends in the selection groups. Genetic trends for PY305 were, as expected, positive for the HMP and HPY groups, and negative for LMP and LCM. The HMP group showed increasing genetic trends for all 3 diseases, arguably a correlated response after selection for increased milk production, whereas the LCM group showed decreasing genetic trends for CM, KET, and RP. The genetic trends for KET and RP in the LCM group are most likely correlated responses after selection against CM. After 5 cow-generations the genetic difference between HPY and LCM was 10 percentage units CM, 1.5 percentage units KET, and 0.5 percentage units RP.

Hepatic glycogen synthase deficiency: an infrequently recognized cause of ketotic hypoglycemia

The glycogen storage diseases comprise several inherited diseases caused by abnormalities of enzymes that regulate the synthesis or degradation of glycogen. In contrast to the classic hepatic glycogen storage diseases that are characterized by fasting hypoglycemia and hepatomegaly, the liver is not enlarged in GSD0. Patients with GSD0 typically have fasting ketotic hypoglycemia without prominent muscle symptoms. Most children are cognitively and developmentally normal. Short stature and osteopenia are common features, but other long-term complications, common in other types of GSD, have not been reported in GSD0. Until recently, the definitive diagnosis of GSD0 depended on the demonstration of decreased hepatic glycogen on a liver biopsy. The need for an invasive procedure may be one reason that this condition has been infrequently diagnosed. Mutation analysis of the GYS2 gene (12p12.2) is a non-invasive method for making this diagnosis in patients suspected to have this disorder. This mini-review discusses the pathophysiology of this disorder, use of mutation analysis to diagnose GSD0, and the clinical characteristics of all reported cases of GSD0.

Genetic analysis of clinical mastitis, milk fever, ketosis, and retained placenta in three lactations of Norwegian red cows

The objectives were to infer heritability and genetic correlations between clinical mastitis (CM), milk fever (MF), ketosis (KET), and retained placenta (RP) within and between the first 3 lactations and to estimate genetic change over time for these traits. Records of 372,227 daughters of 2411 Norwegian Red (NRF) sires were analyzed with a 12-variate (4 diseases x 3 lactations) threshold model. Within each lactation, absence or presence of each of the 4 diseases was scored based on the cow's health recordings. Each disease was assumed to be a different trait in each of the 3 lactations. The model for liability had trait-specific effects of year-season of calving and age of calving (first lactation) or month-year of calving and calving interval (second and third lactations), herd-5-yr, sire of the cow, and a residual. Posterior means of heritability of liability in first, second, and third lactations were 0.08, 0.07, and 0.07, respectively, for CM; 0.09, 0.11, and 0.13 for MF; 0.14, 0.16, and 0.15 for KET, and 0.08 in all 3 lactations for RP. Posterior means of genetic correlations between liability to CM, MF, KET, and RP, within disease between lactations, ranged from 0.19 to 0.86, and were highest between KET in different lactations. Correlations involving first lactation MF were low and had higher standard deviations. Genetic correlations between diseases were low or moderate (from -0.10 to 0.40), within as well as between lactations; the largest estimates were for MF and KET, and the lowest involved MF or KET and RP. Positive genetic correlations between diseases suggest that some general disease resistance factor with a genetic component exists. Trends of average sire posterior means by birth-year of daughters were used to assess genetic change, and the results indicated genetic improvement of resistance to CM and KET and no genetic change for MF and RP in the NRF population.

[Hypoglycaemia without ketosis. A case report]

INTRODUCTION

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare disease, inherited as autosomal-recessive trait, with variable clinical presentation including severe hypoglycaemia, cardiomyopathy, sudden infant death, progressive liver failure, 'Reye like' syndrome, neuromyopathy, muscle weakness and rhabdomyolysis.

CASE REPORT

We report a 3 years old male patient admitted to our emergency department with vomiting, hypotonia and prostration, after a common respiratory infection. The presence of hypoketotic hypoglycaemia and elevated liver enzymes in the admission motivated a metabolic study. We found an abnormal low lactate/pyruvate ratio, decreased serum carnitine and dicarboxylic aciduria leading to the diagnosis of a fatty acid oxidation disorder (LCHADD). The molecular study of HADHA gene revealed homozygosity for the G1528C mutation in the patient DNA, and heterozygosity in both parents.

CONCLUSIONS

The diagnosis of a fatty acid oxidation disorder must be considered in the presence of vomiting associated with excessive prostration specially if there is hypoketotic hypoglycaemia or familiar sudden infant death history. Physicians should be aware about these conditions and for the importance of measuring both glycaemia and ketone bodies during the evaluation of high risk situations.

Patients homozygous for the T435N mutation of succinyl-CoA:3-ketoacid CoA Transferase (SCOT) do not show permanent ketosis

Succinyl-CoA:3-ketoacid CoA transferase (SCOT; locus symbol OXCT; E.C. 2.8.3.5) is the main determinant of the ketolytic capacity of tissues. Hereditary SCOT deficiency causes episodic ketoacidosis. Permanent ketosis has been regarded as a pathognomonic feature of SCOT deficiency. There are three SCOT-deficient patients from a small region in Japan and they have not manifested permanent ketosis, even though their ketoacidotic crises were as severe as those of other SCOT-deficient patients. All three were homozygous for the T435N mutation. Transient expression analysis of wild-type and mutant cDNA showed that the T435N mutant retained significant residual SCOT activities (20% for that of the wild-type at 39.5 degrees C, 25% at 37 degrees C, and 50% at 30 degrees C). The difference of residual SCOT activities at these temperatures in expression analyses was due to differences in the level of the mutant protein. SCOT activity of the T435N protein was more vulnerable than the wild-type to heat treatment at 42 degrees C and 55 degrees C. These temperature-sensitive characteristics of the mutant protein may explain, in part, why the patients developed ketoacidotic crises during febrile illness. In SCOT-deficient patients retaining some residual activity, permanent ketosis may be absent.

Targeted disruption of the pituitary adenylate cyclase-activating polypeptide gene results in early postnatal death associated with dysfunction of lipid and carbohydrate metabolism

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a hormone belonging to the glucagon superfamily of hormones. These hormones are known to play important roles in metabolism and growth. PACAP is a neuropeptide that causes accumulation of cAMP in a number of tissues and affects the secretion of other hormones, vasodilation, neural and immune functions, as well as the cell cycle. To determine whether PACAP is essential for survival and to evaluate its function(s), we have generated mice lacking the PACAP gene via homologous recombination. We found that most PACAP null mice died in the second postnatal week in a wasted state with microvesicular fat accumulation in liver, skeletal muscle, and heart. Gas chromatography-mass spectrometry showed that fatty acid beta-oxidation in liver mitochondria of PACAP(-/-) mice was not blocked based on the distribution of 3-hydroxy-fatty acids (C6-16) in the plasma. Instead, increased metabolic flux through the beta-oxidation pathway was suggested by the presence of ketosis. Also, serum triglycerides and cholesterol were significantly higher (2- to 3-fold) in PACAP null mice than littermates. In the fed state, both serum insulin and blood glucose were normal in 5-d-old null mice compared with their littermates. In contrast, fasted PACAP null pups had a significant increase in insulin, but a decrease in blood glucose compared with littermates. Glycogen in the liver was reduced. These results suggest PACAP is a critical hormonal regulator of lipid and carbohydrate metabolism.

Case report: liver glycogen synthase deficiency--a cause of ketotic hypoglycemia

Glycogen synthase deficiency is a rare inborn error of metabolism, characterized by fasting hypoglycemia, hypoglycemic seizures, and ketonuria. Only 7 families with 14 affected children have been reported. Here, we report an additional patient with this deficiency. Findings in this patient were clinically and biochemically consistent with those reported in patients with ketotic hypoglycemia and may alert the clinician to consider glycogen synthase deficiency.

Hypoglycemia and resistance to ketoacidosis in a subject without functional insulin receptors

Humans with congenital absence of the islets of Langerhans and mice rendered null for the insulin receptor rapidly develop severe hyperglycemia and ketoacidosis and, if untreated, die in the early neonatal period. In contrast, children with homozygous or compound heterozygous mutations of the insulin receptor gene, although hyperglycemic postprandially, survive for many months without developing ketoacidosis. Paradoxically, they often develop hypoglycemia. The rarity of the condition and the difficulties of undertaking metabolic studies in ill infants have limited the physiological information that might explain the clinical features. We studied a boy with Donohue's syndrome who represents a further example of the null phenotype, with two different and novel nonsense mutations in the alpha-subunit of the receptor. He survived for 8 months without developing ketoacidosis, and fasting hypoglycemia was a frequent problem. Despite the complete absence of insulin receptors, evidence for persistent insulin-like effects on fat and liver was seen; fasting plasma beta-hydroxybutyrate and nonesterified fatty acid levels were low, fell further during the early postprandial period, and failed to rise in response to hypoglycemia. The inverse relationships between plasma insulin and insulin-like growth factor-binding protein-1 levels were maintained, suggesting persistent hepatic effects of insulin. GH levels measured over a 6.5-h period were low throughout. Thus, the differences between congenital insulin deficiency vs. insulin receptor deficiency in humans may be explained by persistent insulinomimetic activity of the grossly elevated plasma insulin presumably being mediated through the type 1 insulin-like growth factor receptor. As GH plays a critical role in the regulation of ketogenesis during insulinopenia in humans, but not in rodents, this may contribute to the distinct phenotype of human vs. mouse insulin receptor knockouts.

Kearns-Sayre syndrome presenting as 2-oxoadipic aciduria

A patient with 2-oxoadipic aciduria and 2-aminoadipic aciduria presented at 2 years of age with manifestations typical of organic acidemia, episodes of ketosis and acidosis, progressive to coma. This resolved and the key metabolites disappeared from the urine and blood. At 9 years of age she developed typical Kearns-Sayre syndrome with complete heart block, retinopathy, and ophthalmoplegia. Southern blot revealed a deletion in the mitochondrial genome.

[Genetics of ketosis resistance in cattle]

The frequency of ketosis among the Black-pied cattle in western Siberia have been determined. The genotype of sires and genetic composition of lines were shown to affect resistance and susceptibility to ketosis. The heritability of resistance to the disease was 0.186. Variation in biochemical parameters and natural resistance in cows with ketosis and in healthy cows was studied.

Succinyl CoA: 3-oxoacid CoA transferase (SCOT): human cDNA cloning, human chromosomal mapping to 5p13, and mutation detection in a SCOT-deficient patient

Succinyl CoA: 3-oxoacid CoA transferase (SCOT; E.C.2.8.3.5) mediates the rate-determining step of ketolysis in extrahepatic tissues, the esterification of acetoacetate to CoA for use in energy production. Hereditary SCOT deficiency in humans causes episodes of severe ketoacidosis. We obtained human-heart SCOT cDNA clones spanning the entire 1,560-nt coding sequence. Sequence alignment of the human SCOT peptides with other known CoA transferases revealed several conserved regions of potential functional importance. A single approximately 3.2-kb SCOT mRNA is present in human tissues (heart > leukocytes >> fibroblasts), but no signal is detectable in the human hepatoma cell line HepG2. We mapped the human SCOT locus (OXCT) to the cytogenetic band 5p13 by in situ hybridization. From fibroblasts of a patient with hereditary SCOT deficiency, we amplified and cloned cDNA fragments containing the entire SCOT coding sequence. We found a homozygous C-to-G transversion at nt 848, which changes the Ser 283 codon to a stop codon. This mutation (S283X) is incompatible with normal enzyme function and represents the first documentation of a pathogenic mutation in SCOT deficiency.

Genetic parameters for common health disorders of Holstein cows

Observations on 7416 Canadian Holstein cows were examined to estimate genetic parameters for the most common diseases of dairy cows. Mastitis, ovarian cyst, ketosis, milk fever, abomasal displacement, and culling that is due to reproductive failure or leg problems were analyzed as binomial traits, assuming an underlying threshold model that included fixed and random effects. Sire and residual components of variance were estimated by REML to provide heritability estimates from paternal half-sibs. A multiple-trait mixed model was also used to estimate genetic and environmental correlations between production and disease traits. Heritabilities of disease traits were relatively low and ranged from 0 to .15, except for displaced abomasum (h2 = .28). Evidence of genetic antagonism existed between incidence of mastitis and milk production. Incidence of milk fever was genetically associated with cows of lower genetic potential for production. Genetic associations between displaced abomasum and production traits were small, and estimates of genetic correlations between ovarian cyst and milk production were inconsistent across lactations. Ketosis was antagonistically associated genetically with production of milk and fat but was favorably associated with production of protein. The long-term cumulative effect of genetic selection against diseases might be useful to diminish their incidence.

Impaired ketogenesis in fructose-1,6-bisphosphatase deficiency: a pitfall in the investigation of hypoglycaemia

Intermediary metabolite concentrations were measured in blood during fasting in two patients with fructose-1,6-bisphosphatase deficiency. Hypoglycaemia was accompanied by markedly raised levels of plasma free fatty acids, without the expected degree of ketosis. This suggests that there is secondary impairment of ketogenesis in this condition, and could lead to diagnostic confusion.

Association of major histocompatibility complex antigens (BoLA-A) with AI bull progeny test results for mastitis, ketosis and fertility in Norwegian cattle

Altogether 424 Norwegian AI bulls, progeny tested for clinical mastitis, ketosis and fertility (recorded as nonreturn percentage), were typed by Edinburgh and Oslo allo-antisera to bovine lymphocyte antigens (BoLA-A) over a 7-year period. Significant effects of BoLA-A on disease were revealed. A2 was associated with relative resistance to mastitis, a positive influence on fertility, and a possible relative resistance to ketosis, while A13 was associated with relative resistance to ketosis. The previously reported associations of A11 and w16 with relative susceptibility to mastitis were not confirmed in the present material.

Etiology of acetonemia in Norwegian cattle. 1. Effect of ketogenic silage, season, energy level, and genetic factors

Plasma acetoacetate concentration in the 1st mo of lactation and its relation to BW change, milk yield, DMI, and BW postpartum were studied in 361 first lactation cows during 6 yr. The cows were fed concentrate at 6 and 3 kg/d. Calvings took place from August to December. Single observations for all cows were fitted by a multitrait animal model that accounted for all genetic relationships. Heritability for acetoacetate was .11 with a genetic correlation of .87 for milk yield, -.65 for weight change, and -.13 for BW postpartum. Acetoacetate was higher at 3 kg/d of concentrate than at 6 kg/d, and calving after 3 to 4 mo of indoor feeding was related to higher acetoacetate than was calving shortly after the pasture season. Acetoacetate was related to weight loss postpartum, but at a different degree in different years. In some years, compounds of the silage caused strongly elevated plasma concentrations of acetoacetate after feeding. Experiments were performed to compare hay with silages of different qualities. Rumen concentration of different amines 3 h postfeeding was taken as an index of the amine load of the cow. The concentration of several amines in rumen fluid were high after feeding ketogenic silage.

Clinical ketosis: phenotypic and genetic correlations between occurrences and with milk yield

The repeatability and heritability of ketosis were estimated using data from 28,277 Finnish Ayrshire cows. A four-trait linear model including community-year, calving age and month, genetic group, and random sire effects was used to describe first and second lactation milk yields and veterinary diagnoses of ketosis. Variance components were estimated using REML. The disease traits were also analyzed with a categorical model including the same effects except that community and year were separate factors. Variance components were estimated with marginal maximum likelihood. Genetic relationships between 339 sires analyzed were included in models. The phenotypic correlation between the first and second lactation was defined as a repeatability of trait. The lactational incidence risk of ketosis was .05 in both the first and the second lactation. Average milk production was 4956 and 5547 kg in the first and second lactations, respectively. Estimates of heritabilities were .09 and .07 for ketosis and .23 and .19 for milk in the first and second lactations, respectively. Genetic correlations between first and second lactation recordings were .64 for ketosis and .93 for milk. Repeatabilities between subsequent lactations were .36 (.13 in linear analysis) for ketosis and .68 for milk. In the first lactation, genetic relationship between milk yield and ketosis was unfavorable, but in the second lactation ketosis and milk yield were genetically and phenotypically unrelated.

An epidemiological and genetic study on registered diseases in Finnish Ayrshire cattle. III. Metabolic diseases

The epidemiology of clinical ketosis, hypocalcaemia and hypomagnesaemia was examined. In addition, the genetic variability of ketosis and parturient paresis was investigated. The data set consisted of the lactation records of 70,775 Finnish Ayrshire dairy cows. Each cow was under observation for 2 days before and for 305 days after calving. Lactation incidence rates (%) were: ketosis 6.0, parturient paresis 3.8, non-parturient paresis 0.6, hypomagnesaemic tetany, outdoor 0.6, and indoor 0.2. These diseases formed 22 % of all first treatments by veterinarians during farm visits. 92 % of the cases of ketosis occurred with 8 weeks of parturition, with the highest occurrence 3–5 weeks after calving. Four % of cases of parturient paresis occurred before, and 45 % within 24 h after calving. When cases were categorized by month of calving the risk of ketosis was higher during indoor feeding (October-April) than during outdoor feeding (May-September). The risk of parturient paresis did not significantly vary with month of calving. The occurrence of ketosis increased with parity up to the 4th and decreased thereafter. The occurrence of parturient paresis increased with parity. Both the increase in herd milk yield and the increase in individual milk yields were positively associated with the occurrence of ketosis and parturient paresis. The cows with a history of the reproductive tract infection had a higher risk of contracting ketosis. Heritability estimates for ketosis in various parity groups were from 1.6 % to 4.1 % on the binomial scale (corresponding to 7.3 %–14.4 % on the normal scale), and for parturient paresis from 3.5 to 10.5% (corresponding from 18.3 % to 27.4 %). The genetic correlation between ketosis and parturient paresis, and these and current milk production for all material were insignificant.

Neonatal glutaric aciduria type II: an X-linked recessive inherited disorder

A new case of neonatal glutaric aciduria type II is reported. Neonatal acidosis, hypoglycemia, and hyperammonemia were characteristic. The baby died at four days of age. Organic acid analysis revealed massive glutaric aciduria with elevated concentrations of butyric, isobutyric, n-butyric, and isovaleric acid in his urine. The baby's pedigree suggested strongly an X-linked recessive mode of inheritance. Clinically, biochemically, and genetically glutaric aciduria type II is an heterogeneous disorder. The neonatal form is an X-linked inherited disorder which presents early in life, and is associated with metabolic acidosis, hypoglycemia, and hyperammonemia, and leads to death in the neonatal period. The mild form is an autosomal recessive inherited disease which may present even in adults, and is associated with recurrent hypoglycemia without ketosis and usually improves. Nevertheless the same unusual organic acid pattern is observed in both forms. The basic biochemical defect must be distinct and has not been elucidated.