Curtis R Coughlin II

University of Colorado | UCD · Section of Clinical Genetics and Metabolism

Pyridoxine‐dependent epilepsy (PDE) was historically defined by a dramatic clinical response to a trial of pyridoxine and the re‐emergence of seizures after withdrawal of pyridoxine. Research conducted over the last seven decades has revealed that the phenotype of PDE results from multiple genetic disorders, and the most common disorder, PDE‐ALDH7A...

The Clinical Genome Resource (ClinGen) Consent and Disclosure Recommendation (CADRe) framework proposes that key components of informed consent for genetic testing can be covered with a targeted discussion for many conditions rather than a time-intensive traditional genetic counseling approach. We surveyed US genetics professionals (medical genetic...

Background and Objectives Pyridoxine-dependent epilepsy (PDE-ALDH7A1) is a developmental epileptic encephalopathy characterized by seizure improvement after pyridoxine supplementation. Adjunct lysine reduction therapies reduce the accumulation of putative neurotoxic metabolites with the goal to improve developmental outcomes. Our objective was to e...

Background Little is known about pyridoxine-dependent epilepsy due to α-aminoadipic semialdehyde dehydrogenase deficiency (PDE-ALDH7A1) in adulthood, as the genetic basis of the disorder has only been elucidated 15 years ago. This creates a knowledge gap for physicians, pediatric patients and their parents, which was aimed to address in this study...

Fatty acid oxidation disorders often present with intermittent symptoms triggered by prolonged fasting.Avoidance of fasting is a key component of treatment.Cardiac or skeletal muscle dysfunction are more difficult to treat that the hypoglycemia that defines many of these disorders. Early and consistent treatment with alternate energy sources is hel...

We describe a neonate and a 14-month-old child presenting with seizures that were not (completely) controlled with anti-epileptic medications. There were no signs of infection and electrolytes and neuro-imaging were normal. In the neonate, pyridoxine was administered followed by cessation of seizures and a diagnosis of pyridoxine-dependent epilepsy...

Pyridoxine dependent epilepsy due to mutations in ALDH7A1 (PDH-ALDH7A1) is a highly treatable developmental and epileptic encephalopathy. Pharmacologic doses of pyridoxine are associated with dramatic clinical seizure improvement and most patient achieve adequate seizure control with pyridoxine alone. Unfortunately, patients with PDE-ALDH7A1 have d...

Background Seventy-five percent of patients with pyridoxine-dependent epilepsy due to α-aminoadipic semialdehyde dehydrogenase deficiency (PDE-ALDH7A1) suffer intellectual developmental disability despite pyridoxine treatment. Adjunct lysine reduction therapies (LRT), aimed at lowering putative neurotoxic metabolites, are associated with improved c...

Routine laboratory tests are commonly available and include electrolytes, ammonia, lactate, ketones, and carnitine; these are helpful in evaluating whether a patient may have a metabolic disorder.Metabolic laboratory tests are specialized tests that are reviewed by a biochemical geneticist and include amino acids, acylcarnitines, and organic acids...

Purpose: Informed consent for genetic testing has historically been acquired during pretest genetic counseling, without specific guidance defining which core concepts are required. Methods: The Clinical Genome Resource (ClinGen) Consent and Disclosure Recommendations Workgroup (CADRe) used an expert consensus process to identify the core concept...

Argininosuccinate lyase (ASL) is essential for the NO-dependent regulation of tyrosine hydroxylase (TH) and thus for catecholamine production. Using a conditional mouse model with loss of ASL in catecholamine neurons, we demonstrate that ASL is expressed in dopaminergic neurons in the substantia nigra pars compacta, including the ALDH1A1 + subpopul...

Purpose: Informed consent for genetic testing has historically happened during pre-test genetic counseling, without specific guidance defining which core concepts are required. Methods: The Clinical Genome Resource (ClinGen) Consent and Disclosure Recommendations Workgroup (CADRe) used a modified Expert Delphi consensus process to identify the core...

Background Pyridoxine monotherapy in PDE-ALDH7A1 often results in adequate seizure control, but neurodevelopmental outcome varies. Detailed long-term neurological outcome is unknown. Here we present the cognitive and neurological features of the Dutch PDE-ALDH7A1 cohort. Methods Neurological outcome was assessed in 24 patients (age 1–26 years); cl...

One of the most vital elements of management for patients with inborn errors of intermediary metabolism is the promotion of anabolism, the state in which the body builds new components, and avoidance of catabolism, the state in which the body breaks down its own stores for energy. Anabolism is maintained through the provision of a sufficient supply...

Background Genetic information is increasingly relevant across healthcare. Traditional genetic counseling (GC) may limit access to genetic information and may be more information and support than some individuals need. We report on the application and clinical implications of a framework to consistently integrate genetics expertise where it is most...

Segmental duplications (SDs) are a class of long, repetitive DNA elements whose paralogs share a high level of sequence similarity with each other. SDs mediate chromosomal rearrangements that lead to structural variation in the general population as well as genomic disorders associated with multiple congenital anomalies, including the 7q11.23 (Will...

Pyridoxine‐dependent epilepsy (PDE‐ALDH7A1) is an autosomal recessive condition due to a deficiency of α‐aminoadipic semialdehyde dehydrogenase, which is a key enzyme in lysine oxidation. PDE‐ALDH7A1 is a developmental and epileptic encephalopathy that was historically and empirically treated with pharmacologic doses of pyridoxine. Despite adequate...

Glutaric aciduria type 1 (GA-1) is a cerebral organic aciduria characterized by striatal injury and progressive movement disorder. Nutrition management shifted from a general restriction of intact protein to targeted restriction of lysine and tryptophan. Recent guidelines advocate for a low-lysine diet using lysine-free, tryptophan-reduced medical...

Background As severe obesity continues to rise among youth, metabolic and bariatric surgery (MBS) will increasingly be used as a treatment of choice for durable weight loss and improvement of obesity-related complications. MBS for youth with intellectual and developmental disabilities (IDD) and for preadolescents has raised ethical questions. Obje...

Low protein diet and sodium or glycerol phenylbutyrate, two pillars of recommended long-term therapy of individuals with urea cycle disorders (UCDs), involve the risk of iatrogenic growth failure. Limited evidence-based studies hamper our knowledge on the long-term effects of the proposed medical management in individuals with UCDs. We studied the...

Segmental duplications (SDs) are a class of long, repetitive DNA elements whose paralogs share a high level of sequence similarity with each other. SDs mediate chromosomal rearrangements that lead to structural variation in the general population as well as genomic disorders associated with multiple congenital anomalies, including the 7q11.23 (Will...

We used whole exome sequencing (WES) to determine the genetic etiology of a patient with a multi-system disorder characterized by a seizure phenotype. WES identified a heterozygous de novo missense mutation in the GABRA1 gene (c.875C>T). GABRA1 encodes the alpha subunit of the Gamma-Aminobutyric Acid receptor A (GABAAR). The GABAAR is a ligand gate...

Purpose: Hydrogen sulfide, a signaling molecule formed mainly from cysteine, is catabolized by sulfide:quinone oxidoreductase (gene SQOR). Toxic hydrogen sulfide exposure inhibits complex IV. We describe children of two families with pathogenic variants in SQOR. Methods: Exome sequencing identified variants; SQOR enzyme activity was measured spe...

We used whole exome sequencing (WES) to determine the genetic etiology of a patient with a multi-system disorder characterized by a seizure phenotype. WES identified a heterozygous de novo missense mutation in the GABRA1 gene (c.875C>T). GABRA1 encodes the alpha subunit of the Gamma-Aminobutyric Acid receptor A (GABAAR). The GABAAR is a ligand gate...

This commentary is on the original article by Jiao et al. To view this paper visit https://doi.org/10.1111/dmcn.14385

Low copy repeats (LCRs) are recognized as a significant source of genomic instability, driving genome variability and evolution. The Chromosome 22 LCRs (LCR22s) mediate nonallelic homologous recombination (NAHR) leading to the 22q11 deletion syndrome (22q11DS). However, LCR22s are among the most complex regions in the genome, and their structure re...

The National Institutes of Health (NIH) established the Rare Diseases Clinical Research Network to address the unique challenges of performing research on rare diseases. The Urea Cycle Disorders Consortium (UCDC) was one of the original ten consortia established. The UCDC represents a unique partnership among clinicians, patients, and the NIH with...

Pyridoxine dependent epilepsy (PDE) is a treatable epileptic encephalopathy characterized by a positive response to pharmacologic doses of pyridoxine. Despite seizure control, at least 75% of individuals have intellectual disability and developmental delay. Current treatment paradigms have resulted in improved cognitive outcomes emphasizing the imp...

Objective Patients with severe nonketotic hyperglycinemia have absent psychomotor development and intractable epilepsy, whereas attenuated patients have variable psychomotor development and absent or treatable epilepsy; differences in brain MRI between phenotypes have not been reported. Methods In a retrospective cross‐sectional study, we reviewed...

Pyridoxine‐dependent epilepsy (PDE) is often characterized as an early onset epileptic encephalopathy with dramatic clinical improvement following pyridoxine supplementation. Unfortunately, not all patients present with classic neonatal seizures or respond to an initial pyridoxine trial, which can result in the under diagnosis of this treatable dis...

Beginning in 2006, the Urea Cycle Disorders Consortium (UCDC) has conducted a longitudinal study of eight inherited deficiencies of enzymes and transporters of the urea cycle, including 444 individuals with ornithine transcarbamylase deficiency (OTCD), of whom 300 (67 males, 233 females) received psychological evaluation. In a cross-sectional study...

Organic acidemias and urea cycle disorders are ultra-rare inborn errors of metabolism characterized by episodic acute decompensation, often associated with hyperammonemia, resulting in brain edema and encephalopathy. Retrospective reports and translational studies suggest that N-carbamylglutamate (NCG) may be effective in reducing ammonia levels du...

Low copy repeats (LCRs) are recognized as a significant source of genomic instability, driving genome variability and evolution. The chromosome 22 LCRs (LCR22s) are amongst the most complex regions in the genome and their structure remains unresolved. These LCR22s mediate non-allelic homologous recombination (NAHR) leading to the 22q11 deletion syn...

Purpose: In response to genetic testing being widely ordered by nongenetics clinicians, the Consent and Disclosure Recommendations (CADRe) Workgroup of the Clinical Genome Resource (ClinGen; clinicalgenome.org ) developed guidance to facilitate communication about genetic testing and efficiently improve the patient experience. Considering ethical,...

Pyridoxine dependent epilepsy (PDE) is a treatable epileptic encephalopathy characterized by a positive response to pharmacologic doses of pyridoxine. Despite seizure control, at least 75% of individuals have intellectual disability and developmental delay. Current treatment paradigms have resulted in improved cognitive outcomes emphasizing the imp...

This corrects the article DOI: 10.1038/gim.2016.74.

Background Elevated urinary excretion of orotic acid is associated with treatable disorders of the urea cycle and pyrimidine metabolism. Establishing the correct and timely diagnosis in a patient with orotic aciduria is key to effective treatment. Uridine monophosphate synthase is involved in de novo pyrimidine synthesis. Uridine monophosphate synt...

Background Autosomal recessive or X-linked inborn errors of intracellular cobalamin metabolism can lead to methylmalonic aciduria and homocystinuria. In neonates, both increased cerebrospinal fluid (CSF) glycine and CSF/plasma glycine ratio is a biochemical feature of non-ketotic hyperglycinemia. Patient Description We describe a boy presenting in...

An infant presented with fatal infantile lactic acidosis and cardiomyopathy, and was found to have profoundly decreased activity of respiratory chain complex I in muscle, heart and liver. Exome sequencing revealed compound heterozygous mutations in NDUFB10, an accessory subunit located within the PD part of complex I. One mutation resulted in a pre...

Purpose: The study's purpose was to delineate the genetic mutations that cause classic nonketotic hyperglycinemia (NKH). Methods: Genetic results, parental phase, ethnic origin, and gender data were collected from subjects suspected to have classic NKH. Mutations were compared with those in the existing literature and to the population frequency...

Restrictive cardiomyopathy (RCM) is a rare cause of heart muscle disease with the highest mortality rate among cardiomyopathy types. The etiology of RCM is poorly understood, although genetic causes have been implicated, and syndromic associations have been described. Here, we describe a patient with atrial septal defect and restrictive cardiomyopa...

Background: Pyridoxine-dependent epilepsy is a rare autosomal recessive epileptic encephalopathy caused by antiquitin (ALDH7A1) deficiency. In spite of adequate seizure control, 75% of patients suffer intellectual developmental disability. Antiquitin deficiency affects lysine catabolism resulting in accumulation of α-aminoadipic semialdehyde/pyrro...

Objective: To evaluate the impact of sodium benzoate and dextromethorphan treatment on patients with the attenuated form of nonketotic hyperglycinemia. Study design: Families were recruited with 2 siblings both affected with attenuated nonketotic hyperglycinemia. Genetic mutations were expressed to identify residual activity. The outcome on deve...

Nonketotic hyperglycinemia (NKH) is caused by defective glycine cleavage enzyme activity (► Glycine metabolic scheme). Classic NKH is caused by mutations in protein coding genes (GLDC and AMT). Disorders of lipoate synthesis and transport are caused by mutations in LIAS, BOLA3, NFU1, GLRX5, ISCA2, IBA57, LIPT1, and LIPT2 and can affect glycine meta...

Background and objectives Seventy-five percent of patients with pyridoxine-dependent epilepsy (PDE) due to Antiquitin (ATQ) deficiency suffer developmental delay and/or intellectual disability (IQ). Methods In two open-label observational studies, seven children with confirmed ATQ deficiency were started on dietary lysine restriction with regular n...

Supplementary Information Table 1.

Supplementary Information Table 1.

Nonketotic hyperglycinemia is a neurometabolic disorder characterized by intellectual disability, seizures, and spasticity. Patients with attenuated nonketotic hyperglycinemia make variable developmental progress. Predictive factors have not been systematically assessed. We reviewed 124 patients stratified by developmental outcome for biochemical a...

Short-chain enoyl-CoA hydratase (SCEH, encoded by ECHS1) catalyzes hydration of 2-trans-enoyl-CoAs to 3(S)-hydroxy-acyl-CoAs. SCEH has a broad substrate specificity and is believed to play an important role in mitochondrial fatty acid oxidation and in the metabolism of branched-chain amino acids. Recently, the first patients with SCEH deficiency ha...

Pyridoxine-dependent epilepsy (PDE) is an epileptic encephalopathy characterized by response to pharmacologic doses of pyridoxine. PDE is caused by deficiency of α-aminoadipic semialdehyde dehydrogenase resulting in impaired lysine degradation and subsequent accumulation of α-aminoadipic semialdehyde. Despite adequate seizure control with pyridoxin...

& Objectives: Of patients with pyridoxine-dependent epilepsy (PDE) due to ATQ deficiency, 75% suffer intellectual disability despite adequate seizure control with high dose pyridoxine. We aimed to assess the safety and efficacy of two novel therapeutic strategies to reduce accumulation of toxic intermediates in this cerebral lysine degradation defe...

Mitochondrial disease is often suspected in cases of severe epileptic encephalopathy especially when a complex movement disorder, liver involvement and progressive developmental regression are present. Although mutations in either mitochondrial DNA or POLG are often present, other nuclear defects in mitochondrial DNA replication and protein transla...

Muscle, heart and liver were analyzed in a male subject who succumbed to HSD10 disease. Respiratory chain enzyme analysis and BN-PAGE showed reduced activities and assembly of complexes I, III, IV, and V. The mRNAs of all RNase P subunits were preserved in heart and overexpressed in muscle, but MRPP2 protein was severely decreased. RNase P upregula...

Glutaric acidemia type 1 (GA-1) is an autosomal recessive disorder of lysine, hydroxylysine, and tryptophan metabolism caused by a deficiency of glutaryl-CoA dehydrogenase. It results in the accumulation of 3-hydroxyglutaric and glutaric acid. Patients can present with brain atrophy and macrocephaly, often with concurrent acute dystonia triggered b...

Routine laboratory tests are commonly available and include electrolytes, ammonia, lactate, ketones, and carnitine; these are helpful in evaluating whether a patient may have a metabolic disorder. Metabolic laboratory tests are specialized tests that are reviewed by a biochemical geneticist and include plasma amino acids and acylcarnitines, urine o...

BACKGROUND: Seventy-five percent of patients with pyridoxine-dependent epilepsy (PDE) due to Antiquitin (ATQ) deficiency suffer from developmental delay and/or intellectual disability (IQ < 70) despite seizure control. An observational study showed that adjunct treatment with a lysine-restricted diet is safe, results in partial normalization of lys...

The field of medical genetics has recently undergone a paradigm shift. A genome-first approach to disease identification has started to emerge as untargeted genetic analysis, such as exome sequencing, has been increasingly adopted in the clinic and laboratory. A new model for disclosure of incidental findings must be identified. Ideally, pretest ed...

Knowledge of the genetic basis of human diseases is growing rapidly, with important implications for pre-conception, prenatal, and predictive testing. While new genetic testing offers better insight into the causes of and susceptibility for heritable diseases, not all inherited diseases that can be predicted on the basis of genetic information can...

Background: Seventy-five percent of patients with pyridoxine-dependent epilepsy (PDE) due to Antiquitin (ATQ) deficiency suffer from developmental delay and/or intellectual disability (IQ < 70) despite seizure control. An observational study showed that adjunct treatment with a lysine-restricted diet is safe, results in partial normalization of ly...

Nonketotic hyperglycinemia (NKH) is an inborn error of metabolism characterized by deficient activity of the glycine cleavage enzyme system. This deficiency results in the accumulation of glycine in tissues and the central nervous system and leads to the diagnostic biochemical findings of elevated plasma and cerebrospinal fluid glycine. Classic NKH...

Patients with nonketotic hyperglycinemia and deficient glycine cleavage enzyme activity, but without mutations in AMT, GLDC or GCSH, the genes encoding its constituent proteins, constitute a clinical group which we call 'variant nonketotic hyperglycinemia'. We hypothesize that in some patients the aetiology involves genetic mutations that result in...

Derivatives of vitamin B12 (cobalamin) are essential cofactors for enzymes required in intermediary metabolism. Defects in cobalamin metabolism lead to disorders characterized by the accumulation of methylmalonic acid and/or homocysteine in blood and urine. The most common inborn error of cobalamin metabolism, combined methylmalonic acidemia and hy...

Dihydropteridine reductase (DHPR) deficiency is a genetic disorder of tetrahydrobiopterin (BH4) regeneration and may present with hyperphenylalaninemia, microcephaly, hypotonia, mental retardation, and convulsions. BH4 is an essential cofactor for the hydroxylation of aromatic amino acids and a deficiency of BH4 results in decreased synthesis of do...

We present a neonate with molybdenum cofactor deficiency imaged at presentation during the first month of life and at 5 months with diffusion-weighted brain MRI. While the imaging features of this disease have previously been reported, this case highlights a distinctive initial pattern of widespread restricted diffusion involving cortex at the dept...

Copy number variation (CNV) analysis has had a major impact on the field of medical genetics, providing a mechanism to identify disease-causing genomic alterations in an unprecedented number of diseases and phenotypes. CNV analysis is now routinely used in the clinical diagnostic laboratory, and has led to a significant increase in the detection of...

OBJECTIVE: To evaluate the efficacy and safety of dietary lysine restriction as an adjunct to pyridoxine therapy on biochemical parameters, seizure control, and developmental/cognitive outcomes in children with pyridoxine-dependent epilepsy (PDE) caused by antiquitin (ATQ) deficiency. METHODS: In this observational study, seven children with confir...