Browse Health


Education ?

Medical School
University Of Toronto Faculty Of Medicine (1982)
Foreign school

Awards & Distinctions ?

Compassionate Doctor Recognition (2014)
Top 10 Doctor - City (2014)
Boston, MA
American Board of Medical Genetics

Affiliations ?

Dr. Korson is affiliated with 2 hospitals.

Hospital Affiliations



  • Children's Hospital
    300 Longwood Ave, Boston, MA 02115
  • Tufts Medical Center
    750 Washington St, Boston, MA 02111
  • Publications & Research

    Dr. Korson has contributed to 22 publications.
    Title Newborn Screening for Hepatorenal Tyrosinemia by Tandem Mass Spectrometry: Analysis of Succinylacetone Extracted from Dried Blood Spots.
    Date June 2005
    Journal Clinical Biochemistry

    OBJECTIVES: To develop a method for the determination of succinylacetone (SA) in dried blood spots (DBS) using tandem mass spectrometry (MS/MS). METHODS: SA was extracted from DBS with an acetonitrile and water solution (80:20 by volume) containing formic acid and hydrazine hydrate (both at 0.1% by volume), and analyzed by MS/MS with a total run time per sample under 2 min. The reference range for SA in newborns was determined by analyzing a control group of 3199 DBS. SA was also measured in stored newborn specimens from three patients diagnosed clinically with hepatorenal tyrosinemia (HT). RESULTS: The within-run precision was <or=7.4% and total precision was <or=12.2% on blood spots fortified with SA at 2, 10, and 50 micromol/L. The limit of quantitation was 1 micromol/L and the calibration was linear from 1 to 50 micromol/L. A comparison of SA analysis of this MS/MS method with an established enzyme assay indirectly quantitating SA by inhibition of delta-aminolevulinic acid dehydratase demonstrated a strong correlation. The reference range in the control group of unaffected newborn was determined to be <2 micromol/L, while SA in retrieved DBS from HT patients was significantly elevated, measuring 46.7, 36.5, and 23.2 micromol/L. CONCLUSIONS: We report a simple method that can be used for screening HT in newborns. Based on our limited experience, a 2 micromol/L cutoff could result in up to 100% sensitivity and specificity.

    Title Determination of Phenylalanine and Tyrosine in Dried Blood Specimens by Ion-exchange Chromatography Using the Hitachi L-8800 Analyzer.
    Date February 2005
    Journal Clinical Biochemistry

    OBJECTIVES: The treatment for phenylketonuria (PKU) includes monitoring blood phenylalanine (Phe) levels on a regular basis. To reduce inconvenience to the patient and family, blood specimens on filter paper can be obtained at home and mailed to the clinic or analytical laboratory. For this reason, we validated an 8-min isothermal and isocratic HPLC method using the Hitachi L-8800 analyzer for quantitation of Phe and tyrosine (Tyr) from dried blood specimens (DBS). DESIGN AND METHODS: The method was worked out using DBS fortified with Phe and Tyr. For method comparison, blood samples from 31 PKU patients and 5 non-PKU volunteers were analyzed as DBS by HPLC using the Hitachi L-8800 analyzer, and compared both to plasma analyzed by HPLC and DBS analyzed using tandem mass spectrometry (MS/MS). RESULTS: For HPLC analysis of DBS, the within-run precision for Phe and Tyr was < or = 5.1% and < or = 4.5%, respectively, and total precision measured over a 3-month period was < or = 7.2% and < or = 8.7%, respectively. Correlation analysis was performed using results from fresh plasma analyzed by HPLC (r = 0.988 for Phe, r = 0.964 for Tyr) and from DBS analyzed by MS/MS (r = 0.960 for Phe, r = 0.942 for Tyr). Difference plots revealed good agreement between the HPLC and MS/MS methods. CONCLUSIONS: Determination of Phe and Tyr in DBS using this HPLC technique compares well with other methods. This technique with its short analytical time is convenient for monitoring patients with PKU and might be particularly useful in centers following many patients.

    Title Neuropsychiatric Illness in a Patient with Cobalamin G Disease, an Inherited Disorder of Vitamin B12 Metabolism.
    Date July 2004
    Journal Harvard Review of Psychiatry
    Title The Importance of Gut Motility in the Metabolic Control of Propionic Acidemia.
    Date May 2004
    Journal The Journal of Pediatrics

    We hypothesized that gut motility likely plays a critical role in the metabolic stability in propionic acidemia (PA). Therefore, 4 known patients with PA (aged 47 months to 185 months) were prospectively studied over 7 days in the Clinical Research Center at Children's Hospital, Boston. Determinations of ammonia, bicarbonate, and amino acids in blood; organic acids and propionylglycine in urine; and a lactulose breath test were conducted under two study conditions: on regular therapy (for 4 days) and on regular therapy plus Senekot (Purdue Frederick Company, Norwalk, Conn), an intestinal motility agent (for 3 days). The total gastrointestinal transit time was calculated using 20 nonabsorbable, inert, radio-opaque markers. The addition of an intestinal motility agent resulted in a significant decrease in blood ammonia, urinary excretion of propionylglycine, and a rise in the ratio of free to total carnitine over baseline. We concluded that enhancement of gut motility can improve metabolic stability in patients with PA.

    Title Four Cases with Hypoplastic Thumbs and Encephaloceles.
    Date January 2003
    Journal American Journal of Medical Genetics

    We report on four infants with hypoplastic thumbs and occipital encephaloceles. None had either a chromosome abnormality or a family history of any major malformation. The literature and database were searched intensively. No similar cases were reported previously, suggesting that the constellations might represent a new genetic syndrome.

    Title New England Consortium: a Model for Medical Evaluation of Expanded Newborn Screening with Tandem Mass Spectrometry.
    Date December 2001
    Journal Journal of Inherited Metabolic Disease
    Title Tyrosine Supplementation in Phenylketonuria: Diurnal Blood Tyrosine Levels and Presumptive Brain Influx of Tyrosine and Other Large Neutral Amino Acids.
    Date October 2001
    Journal The Journal of Pediatrics

    Tyrosine supplementation has not consistently been found to improve neuropsychologic function in phenylketonuria (PKU), possibly because of failure to achieve adequate levels of tyrosine in the brain. OBJECTIVES: To evaluate blood levels achieved after tyrosine supplementation in treated PKU and calculate brain influxes of tyrosine and other large neutral amino acids before and with tyrosine supplementation. STUDY DESIGN: Ten subjects with PKU receiving a phenylalanine-restricted diet were studied over 48 hours; each received tyrosine supplementation (300 mg/kg) on day 2. Plasma phenylalanine and tyrosine were measured every 2 hours, and all free amino acids were measured every 6 hours. Brain influxes of tyrosine and other large neutral amino acids were calculated. RESULTS: Plasma tyrosine levels were low normal at baseline. With supplementation there was a substantial but unsustained rise in plasma tyrosine. Calculated brain influx of tyrosine was 27% +/- 19% of normal before supplementation, increasing to 90% +/- 58% of normal with supplementation. Nevertheless, calculated influx remained less than 70% of normal at 50% of the time points. The calculated brain influxes of all other large neutral amino acids except tryptophan were 20% to 40% of normal before and with tyrosine supplementation. CONCLUSIONS: Tyrosine supplementation in the diet for PKU produces marked but nonsustained increases in plasma tyrosine levels, with calculated brain influx that often remains suboptimal. This could explain the lack of consistent neuropsychologic benefit with tyrosine supplementation.

    Title Urinary Lactate Excretion to Monitor the Efficacy of Treatment of Type I Glycogen Storage Disease.
    Date September 2000
    Journal Molecular Genetics and Metabolism

    The purpose of this study was to investigate the usefulness of urinary lactate measurements to assess the adequacy of dietary treatment in patients with type I glycogen storage disease (GSD-I). We determined the correlation of urine and blood lactate concentrations in 21 GSD-I patients during 24-h admissions to the General Clinical Research Center (GCRC) during which hourly blood samples and aliquots of every void were obtained. In all but 1 patient, we found a good correlation between blood lactate concentrations and urinary lactate excretion. One patient did not excrete lactate in significant amounts despite elevated blood lactate concentrations. In 17 patients, the highest blood lactate concentrations occurred during the night. Markedly elevated nighttime average blood lactate concentrations above 3.5 mmol/l resulted in a urinary lactate concentration above the normal limit of 0.067 mmol/mmol creatinine in the first morning urine specimen. Mildly elevated nighttime blood lactate concentrations (between 2.2 and 3.5 mmol/l) led to urinary lactate concentrations that were either normal or moderately elevated. All patients with normal blood lactate concentrations during the night also had normal first morning urinary lactate concentrations. The degree of urinary lactate excretion in relation to blood lactate concentrations varied by individual. Urinary filter paper specimens, collected at home during the night and in the morning and mailed to the laboratory, were used to monitor the dietary compliance of 5 GSD-I patients at home over a period of 6 to 9 weeks prior to their GCRC admissions. These data suggested variable degrees of dietary control. In conclusion, the urinary lactate concentration is a useful parameter to monitor therapy of GSD-I patients at home. To be interpretable, the baseline urinary lactate concentration in relation to the blood lactate concentration has to be determined.

    Title Advances in Newborn Screening for Metabolic Disorders: What the Pediatrician Needs to Know.
    Date August 2000
    Journal Pediatric Annals
    Title Quality of Life Assessment in Adults with Type 1 Gaucher Disease.
    Date September 1999
    Journal Quality of Life Research : an International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation

    The effect of enzyme replacement therapy on health-related quality of life in 25 adults with type 1 Gaucher disease was investigated over a 2-year period. Quality of life was assessed using the SF-36 Health Survey (SF-36). Psychological functioning was assessed using the Symptom Checklist--90R. The results indicated significant improvement in 7 of 8 SF scale scores beginning at 18 months of therapy (P < 0.05 to 0.001). The SF scale showing improvement first was Vitality (energy level and fatigue) at 6 months of therapy (P < 0.01). The SF-36 scales showing the largest improvements were Role-Physical and Social Functioning (P < 0.001). Compared to the general US adult population, the study population's health profile was significantly lower prior to starting therapy but by 24 months of therapy there were no differences between the two. No differences were found in psychological functioning compared to a US adult normative group at the start of therapy. However, within the study population there was significant improvement in mood and global functioning and fewer psychological symptoms reported at 24 months of therapy. The findings indicate that enzyme replacement therapy for type 1 Gaucher disease has a positive impact on health-related quality of life from the patient's perspective.

    Title A Gc/ms/ms Screening Method for Multiple Organic Acidemias from Urine Specimens.
    Date August 1999
    Journal Clinica Chimica Acta; International Journal of Clinical Chemistry

    A gas chromatography tandem mass spectrometry method using an ion trap GC/MS system was developed to quickly screen urine samples for 14 organic acids associated with multiple organic acidemias. The following organic acids are used as diagnostic markers: methylmalonic acid, glutaric acid, 2-ketoisocaproic acid, succinylacetone, 3-methylcrotonylglycine, tiglylglycine, isovalerylglycine, fumaric acid, butyrylglycine, propionylglycine, hexanoylglycine, adipic acid, suberic acid, and sebacic acid. 2-ketocaproic acid is used as an internal standard. The samples are prepared using a solid-phase extraction and converted to trimethylsilyl derivatives. The extraction efficiency for the 14 compounds is between 57 and 106%. A derivatized standard mixture of the 14 markers is run prior to the patient samples to determine the accurate absolute and relative retention times. The samples are then injected and the product ion spectra monitored. For data analysis, one characteristic product ion plot is extracted for each of the 14 marker compounds, and the presence of a peak with the expected retention time is determined. The areas of the product ion peaks are compared with the reference range determined from 30 normal controls. Ten samples of patients with known organic acidemias were measured. For all patients, diagnostic peaks at the expected retention times of at least five times the upper limit of the reference range were detected. The method, with its relatively fast sample preparation, short 10.0 min run time and simple data analysis, is suitable for use as a quick metabolic screen of very sick patients in whom there is concern regarding the possibility of a treatable inborn error.

    Title Quantification of Glutaric Acid by Isotope Dilution Mass Spectrometry for Patients with Glutaric Acidemia Type I: Selected Ion Monitoring Vs. Selected Ion Storage.
    Date July 1999
    Journal Clinica Chimica Acta; International Journal of Clinical Chemistry

    An isotope dilution mass spectrometric assay for the quantification of glutaric acid in urine and serum samples was developed. The performance of a quadrupole mass filter (QMF) gas chromatography-mass spectrometry (GC-MS) instrument, operated in the selected ion monitoring mode, and a quadrupole ion trap (QIT) GC/MS instrument, operated in the selected ion storage mode, was compared. Both instruments gave linear standard curves with glutaric acid concentrations between 0.19 and 3.8 microM. The average coefficients of correlation were 0.9998 and 0.9993 for the QMF and the QIT system, respectively. There was good agreement between the glutaric acid concentrations measured with the two instruments. The run-to-run precision was between 1.2 and 3.7% and between 6.2 and 8.6%, the average recovery of glutaric acid in urine and serum samples was 96 and 103% with the QMF and QIT instrument, respectively. We conclude that although the QMF has a slightly better performance, both instruments can be used to reliably measure glutaric acid concentrations from urine and serum patient samples.

    Title Reversal of Severe Hypertrophic Cardiomyopathy and Excellent Neuropsychologic Outcome in Very-long-chain Acyl-coenzyme A Dehydrogenase Deficiency.
    Date September 1998
    Journal The Journal of Pediatrics

    Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is a disorder of fatty acid beta oxidation that reportedly has high rates of morbidity and mortality. We describe the outcome of a 5-year-old girl with VLCAD deficiency who was first seen at 5 months of age with severe hypertrophic cardiomyopathy, hepatomegaly, encephalopathy, and hypotonia. Biochemical studies indicated VLCAD deficiency caused by a stable yet inactive enzyme. Molecular genetic analysis of her VLCAD gene revealed a T1372C (F458L) missense mutation and a 1668 ACAG 1669 splice site mutation. After initial treatment with intravenous glucose and carnitine, the patient has thrived on a low-fat diet supplemented with medium-chain triglyceride oil and carnitine and avoidance of fasting. Her ventricular hypertrophy resolved significantly over 1 year, and cognitively, she is in the superior range for age. Clinical recognition of VLCAD deficiency is important because it is one of the few directly treatable causes of cardiomyopathy in children.

    Title Inadequate Laboratory Technique for Amino Acid Analysis Resulting in Missed Diagnoses of Homocystinuria.
    Date April 1998
    Journal Clinical Chemistry
    Title Perioperative White Matter Degeneration and Death in a Patient with a Defect in Mitochondrial Oxidative Phosphorylation.
    Date September 1997
    Journal Anesthesiology
    Title Clinical Approach to Genetic Cardiomyopathy in Children.
    Date December 1996
    Journal Circulation

    BACKGROUND: Cardiomyopathy (CM) remains one of the leading cardiac causes of death in children, although in the majority of cases, the cause is unknown. To have an impact on morbidity and mortality, attention must shift to etiology-specific treatments. The diagnostic evaluation of children with CM of genetic origin is complicated by the large number of rare genetic causes, the broad range of clinical presentations, and the array of specialized diagnostic tests and biochemical assays. METHODS AND RESULTS: We present a multidisciplinary diagnostic approach to pediatric CM of genetic etiology. We specify criteria for abnormal left ventricular systolic performance and structure that suggest CM based on established normal echocardiographic measurements and list other indications to consider an evaluation for CM. We provide a differential diagnosis of genetic conditions associated with CM, classified as inborn errors of metabolism, malformation syndromes, neuromuscular diseases, and familial isolated CM disorders. A diagnostic strategy is offered that is based on the clinical presentation: biochemical abnormalities, encephalopathy, dysmorphic features or multiple malformations, neuromuscular disease, apparently isolated CM, and pathological specimen findings. Adjunctive treatment measures are recommended for severely ill patients in whom a metabolic cause of CM is suspected. A protocol is provided for the evaluation of moribund patients. CONCLUSIONS: In summary, we hope to assist pediatric cardiologists and other subspecialists in the evaluation of children with CM for a possible genetic cause using a presentation-based approach. This should increase the percentage of children with CM for whom a diagnosis can be established, with important implications for treatment, prognosis, and genetic counseling.

    Title Oxidative Phosphorylation Defect Associated with Primary Adrenal Insufficiency.
    Date June 1996
    Journal The Journal of Pediatrics

    An 18-month-old girl with an oxidative phosphorylation defect had neonatal onset of chronic lactic acidosis, lipid storage myopathy, bilateral cataracts, and primary adrenal insufficiency. Chronic lactic acidosis responded to treatment with dichloroacetate. Sequential muscle biopsies demonstrated resolution of the lipid storage myopathy associated with the return to normal muscle free carnitine levels. This case demonstrates a new clinical phenotype associated with a defect in oxidative phosphorylation and the need to consider mitochondrial disorders in the differential diagnosis of primary adrenal insufficiency in childhood.

    Title Bilateral Infantile Cataractogenesis in a Patient with Deficiency of Complex I, a Mitochondrial Electron Transport Chain Enzyme.
    Date March 1996
    Journal Journal of Pediatric Ophthalmology and Strabismus

    Progressive bilateral cataracts developed in infancy in a 5-month-old girl with deficiency of complex I, a mitochondrial electron transport chain enzyme. In the newborn period, she had severe lactic acidosis and the diagnosis of complex I deficiency was confirmed by mitochondrial respiratory chain assay on muscle biopsy. By 5 months, she had completely opaque nuclear sclerotic cataracts, with loss of fixation and the red reflex. She underwent bilateral, sequential cataract extraction. The lens aspirate was submitted for cytologic analysis and electron microscopy, which revealed increased intracellular glycogen and swollen mitochondria. To our knowledge the association of complex I deficiency with cataracts in infancy has not been reported previously. The diagnosis of a respiratory chain enzyme defect in infancy is an indication for early ophthalmic evaluation to identify cataracts that may result in visual loss. Conversely, the recognition of cataracts in infants with unexplained neurologic disease or metabolic acidosis may necessitate further evaluation for metabolic etiologies, including mitochondrial disorders.

    Title Lethal Neonatal Deficiency of Carnitine Palmitoyltransferase Ii Associated with Dysgenesis of the Brain and Kidneys.
    Date October 1995
    Journal The Journal of Pediatrics

    We describe neonatal onset of a lethal multiorgan deficiency of carnitine palmitoyltransferase II (CPT II) associated with dysmorphic features, cardiomyopathy, and cystic dysplasia of the brain and kidneys. Concentrations of long-chain acylcarnitines were evaluated in blood and multiple tissues, diffuse lipid accumulation was present at autopsy, and a profound deficiency of CPT II activity was evident in heart, liver, muscle, and kidney tissue. This disorder constitutes another recognizable malformation syndrome with a metabolic basis. Deficiency of CPT II should be included in the differential diagnosis of patients with cystic renal dysplasia, dysmorphism, central nervous system malformations, and early death, along with glutaric acidemia type II, Zellweger syndrome, and other disorders in which peroxisomal beta-oxidation is impaired. The clinicopathologic similarities among these disorders raise the possibility that a common biochemical mechanism, namely the disruption of beta-oxidation of fatty acids, is responsible for the abnormal organogenesis.

    Title A Missense Mutation (i278t) in the Cystathionine Beta-synthase Gene Prevalent in Pyridoxine-responsive Homocystinuria and Associated with Mild Clinical Phenotype.
    Date August 1995
    Journal American Journal of Human Genetics

    Cystathionine beta-synthase (CBS) deficiency is an autosomal recessive disorder characterized by homocystinuria and multisystem clinical disease. Patients responsive to pyridoxine usually have a milder clinical phenotype than do nonresponsive patients, and we studied the molecular pathology of this disorder in an attempt to understand the molecular basis of the clinical variation. We previously reported a T833C transition in exon 8 causing a substitution of threonine for isoleucine at codon 278 (I278T). By PCR amplification and sequencing of exon 8 from genomic DNA we have now detected the I278T mutation in 7 of 11 patients with in vivo pyridoxine responsiveness and in 0 of 27 pyridoxine-nonresponsive patients. Two pyridoxine-responsive patients are homozygous and five are heterozygous for I278T. We have now observed the I278T mutation in 41% (9 of 22) of the independent alleles in pyridoxine-responsive patients of varied ethnic backgrounds. In two of the compound heterozygotes we identified a novel mutation (G139R and E144K) in the other allele. The finding that the two patients who are homozygous for I278T have only ectopia lentis and mild bone demineralization suggests that this mutation is associated with both in vivo pyridoxine responsiveness and mild clinical disease. Compound heterozygous patients who have one copy of this missense mutation are likely to retain some degree of pyridoxine responsiveness.

    Title Neonatal-onset Propionic Acidemia: Neurologic and Developmental Profiles, and Implications for Management.
    Date July 1995
    Journal The Journal of Pediatrics

    OBJECTIVES: To document the clinical and neurodevelopmental profiles of a cohort of patients with neonatal-onset propionic acidemia and to determine the efficacy of current therapy with respect to outcome. METHOD: The clinical, neurologic, and developmental status of six patients was prospectively evaluated during a 15-month period. Previous clinical and biochemical data were ascertained from hospital records to determine longitudinal nutritional status, number of episodes of hyperammonemia with ketoacidosis, and developmental performance with respect to age. RESULTS: No deaths resulted from propionic acidemia since the identification of the oldest patient in the series in 1980. Therapeutic intervention (e.g., gastrostomy tube feeding) resulted in improved nutritional status and possibly contributed to improved survival. All children had hypotonia, resulting in a significant effect on motor development; however, focal neurologic deficits and evidence of movement or seizure disorder were absent. Mild cortical atrophy was evident on cranial magnetic resonance imaging in four patients. All children, including two patients with no significant episodes of hyperammonemia and normal growth since the neonatal period, had a mild to moderate degree of intellectual impairment. CONCLUSIONS: The results of our study suggest that current therapy for neonatal-onset propionic acidemia is associated with improved survival and nutritional status, and an absence of focal neurologic deficits. However, hypotonia and cognitive delay were still present, even in children with "optimal" metabolic control. Additional therapeutic advances are required to improve the developmental and cognitive outcome.

    Title Pitfalls in Diagnosing Galactosemia: False Negative Newborn Screening Following Red Blood Cell Transfusion.
    Date March 1990
    Journal Journal of Pediatric Gastroenterology and Nutrition

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