Molecular Genetics and Metabolism 103 (2011) 92–95
Contents lists available at ScienceDirect
Molecular Genetics and Metabolism j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / y m g m e
Brief Communication
Maternal medium-chain acyl-CoA dehydrogenase deficiency identified by newborn screening K.B. Leydiker a, J.A. Neidich b, F. Lorey c, E.M. Barr a, R.L. Puckett a, R.M. Lobo b, J.E. Abdenur a,⁎ a b c
Division of Metabolic Disorders, CHOC Children's, 455 S. Main St., Orange, CA, 92868, USA Quest Diagnostics Nichols Institute, 33608 Ortega Highway San Juan Capistrano, CA, 92675, USA Genetic Disease Screening Program, CA Department of Public Health, 850 Marina Bay Parkway, Richmond, CA 94804, USA
a r t i c l e
i n f o
Article history: Received 21 December 2010 Received in revised form 21 January 2011 Accepted 21 January 2011 Available online 27 January 2011 Keywords: Medium-chain acyl-CoA dehydrogenase deficiency Expanded newborn screening Maternal Tandem mass spectrometry MCADD Maternal inborn error of metabolism
a b s t r a c t Prior to the advent of expanded newborn screening, sudden and unexplained death was often the first and only symptom of medium-chain acyl-CoA dehydrogenase deficiency (MCADD). With the use of tandem mass spectrometry, infants can now be identified and treated before a life threatening metabolic decompensation occurs. Newborn screening has also been shown to detect previously undiagnosed maternal inborn errors of metabolism. We have now diagnosed two women with MCADD following the identification of low free carnitine in their newborns. While one of the women reported prior symptoms of fasting intolerance, neither had a history of metabolic decompensation or other symptoms consistent with a fatty acid oxidation disorder. These cases illustrate the importance of including urine organic acid analysis and an acylcarnitine profile as part of the confirmatory testing algorithm for mothers when low free carnitine is identified in their infants. © 2011 Published by Elsevier Inc.
1. Introduction Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an autosomal recessive fatty acid oxidation defect caused by mutations in the ACADM gene mapped to 1p31 [1]. The ACADM gene encodes a 421 amino acid protein, known as the medium-chain acyl-CoA dehydrogenase, which catalyzes the initial reaction in the mitochondrial betaoxidation of C4–C12 fatty acids [1,2]. Deficiency of this enzyme is characterized by severe metabolic decompensation during periods of prolonged fasting or illness. Without swift intervention, these episodes can result in hypoketotic hypoglycemia, Reye-like syndrome, coma and death. Prior to the advent of expanded newborn screening, with the use of tandem mass spectrometry (MS/MS), sudden and unexplained death was often the first and only symptom of MCADD [3–5]. Currently, newborn screening can detect elevated medium chain acylcarnitines in dried blood spots, allowing for the identification of infants with MCADD [6–9]. MS/MS has also been shown to diagnose some maternal inborn errors of metabolism. For example, the presence of elevated metabolites in newborns has led to the identification of maternal 3-methylcrotonyl-CoA carboxylase deficiency and holocarboxylase synthetase deficiency [10,11]. In contrast,
⁎ Corresponding author. Fax: + 1 714 532 8362. E-mail address:
[email protected] (J.E. Abdenur). 1096-7192/$ – see front matter © 2011 Published by Elsevier Inc. doi:10.1016/j.ymgme.2011.01.011
decreased free carnitine in newborns has led to the diagnosis of maternal carnitine transport defects, asymptomatic glutaric aciduria Type I and combined homocystinuria and methylmalonic aciduria (cblC defect) [12–17]. We now present the case reports of two women, who were diagnosed with MCADD following the abnormal newborn screening of their infants. 2. Materials and methods Our patients were brought to clinical attention after the expanded newborn screening results of their children revealed low free carnitine. Confirmatory testing for the newborns included plasma and urine carnitine. Testing for the mothers included plasma and urine carnitine, acylcarnitine profiles, and urine organic acids. Once the abnormal maternal acylcarnitine profiles were identified, acylcarnitine profiles were then ordered on the newborns, as well. At the time of diagnosis, both mothers met with a metabolic dietician who initiated a nutrition care plan consistent with The Genetic Metabolic Dietitians International (GMDI) consensus on the management of adult patients with MCADD [37]. They were instructed to follow a heart healthy diet, deriving 30% of calories from fat, and to avoid periods of fasting by consuming frequent meals and snacks containing complex carbohydrates. They were advised to use uncooked cornstarch prior to bedtime to reduce the risks associated with overnight fasting. Both mothers were provided with genetic counseling by a board certified genetic counselor and
K.B. Leydiker et al. / Molecular Genetics and Metabolism 103 (2011) 92–95
educated about the risks for their siblings, offspring and extended families. Both mothers were given emergency protocol letters for use in the event of a metabolic decompensation. Newborn screening was performed by the California Newborn Screening Program using tandem mass spectrometry. The newborn screening specimen for Infant 1 was collected at 15 h of life. The newborn screening specimen for Infant 2 was collected at 25 h of life. Additional testing was performed at the following accredited laboratories using standard methodology: Quest Diagnostics, Inc., Nichols Institute (confirmatory testing for the newborns and their mothers), Duke University Biomedical Genetics Lab (urinary carnitine analysis), CHOC Children's Metabolic Laboratory (follow-up biochemical testing for the newborns and their mothers), and Baylor College of Medicine, Medical Genetics Laboratories (molecular sequencing for mother 1). 3. Results Physical examinations of the newborns and their mothers were normal. Results of the newborn screening and confirmatory testing are summarized in Table 1. On confirmatory testing after NBS, both newborns had low levels of total and free carnitine in plasma, with normal urine carnitine. Plasma carnitine levels normalized in both infants without treatment and their acylcarnitine profiles were normal. In contrast, both mothers had a low total and free carnitine in plasma. Urine organic acids revealed elevated suberylglycine and hexanoglycine in both patients. Dicarboxylic acids were within normal limits for Mother 1 and were borderline elevated in Mother 2. Acylcarnitines showed elevated C6, C8, C10:1 and C8/C10 ratios consistent with MCADD. Carnitine supplementation was initiated in both mothers, along with fasting precautions and a heart healthy diet. Plasma carnitine levels normalized in Mother 1. Carnitine levels trended up in Mother 2 after two days of carnitine supplementation. Sequencing of the ACADM gene revealed that Mother 1 is homozygous c.985A N G (p. K329E), a mutation, generally, associated with a severe MCADD phenotype[18–22] Additional labs for Mother 1 included a normal creatine phosphokinase. We were unable to perform sequencing for
93
Mother 2 because she did not return to the clinic for further evaluation. 4. Discussion and conclusions The identification of maternal MCADD through newborn screening provides evidence that expanded newborn screening not only identifies infants with MCADD, but may also identify affected mothers, who are at risk to experience life-threatening metabolic decompensations. Of particular importance, our maternal MCADD patients were identified through the low free carnitine levels of their newborns, rather than through elevations of C6, C8 or C10:1 on newborn screening. This has significant implications for determining which confirmatory studies should be performed following the identification of low free carnitine on newborn screening. The American College of Medical Genetics (ACMG) ACT Sheet for decreased free carnitine recommends the evaluation of total and free carnitine in plasma and urine for the infant only, with a caveat to rule out maternal carnitine transport defect and glutaric aciduria type 1. However, as the number of maternal conditions identifiable by newborn screening continues to increase, the recommendations should be updated accordingly. Therefore, based on our experience, we would suggest that these guidelines be modified to include urine organic acid analysis and plasma and urine carnitine levels for both infants and their mothers as part of the standard confirmatory testing process, as is currently recommended by the State of California Newborn Screening Program. Of note, the low free carnitine in our maternal patients reflected a secondary carnitine deficiency due to MCADD. Therefore, a second acylcarnitine profile may be indicated in similar cases once maternal carnitine levels are replete in order to avoid false negative results. This fact should also be taken into account when considering appropriate guidelines for confirmatory testing. During a review of clinical history, Mother 1 described symptoms of fasting intolerance including headache, irritability, nausea and somnolence. To ameliorate these symptoms, she had already selfimposed a regimen of eating every three hours during the day with a maximum overnight fast of ten hours. During her second pregnancy
Table 1 Biochemical results in newborns and their mothers.
Before treatment Newborn screening Plasma carnitine Total Free Urine carnitine Total Free Acylcarnitines C6 C8 C10:1 Urine organic acids
After treatment Plasma carnitine Total Free Acylcarnitines C6 C8 C10:1
Newborn 1
Mother 1
Newborn 2
Mother 2
C0 = 10.9 b12*
N/A
C0 = 5.1 b7.1*
N/A
10 (32–62) 6 (25–54)
15 (25–58) 10 (19–48)
12 (32–62) 9 (25–54)
7 (25–58) 3 (19–48)
173 (125 +/− 75) 26 (51 +/− 40)
N/A
235(125 +/− 75) 76 (51 +/− 40)
81(125 +/− 75) 12 (51 +/− 40)
0.08 (b 0.10) 0.11 (b 0.35) 0.09 (b 0.64) N/A
0.34 (b 0.09) 1.57 (b 0.65) 0.59 (b 0.81) SG = 29 (0) HG = 6 (0)
b0.12 (b0.34) b0.15 (b0.21) b0.07 (b0.18) N/A
0.17 (b 0.09) 1.50 (b 0.65) 0.79 (b 0.81) SG = 45 (0) HG = 11 (0)
28 (32–62) 21 (25–54)
44.5 (25–58) 25.1 (19–48)
43.9 (32–62) 30.3 (25–54)
16.9 (25–58) 9.4 (19–48)
N/A
0.83 (b 0.34) 3.65 (b 0.21) 1.04 (b 0.18)
N/A
0.23 (b 0.34) 1.52 (b 0.21) 0.63 (b 0.18)
Units of measure: NBS free carnitine = μmol/L; plasma carnitine = μmol/L; urine carnitine = nmol/mg of creatinine; acylcarnitines = μmol/L, urine organic acids = μmol/mol creatinine. *Please note that the cut-off for C0 is different for Infant 1 and 2 due to a change in methodology by the California Department of Public Health, NBS program.
94
K.B. Leydiker et al. / Molecular Genetics and Metabolism 103 (2011) 92–95
she reported increased fatigue and episodes of feeling faint. Apart from these symptoms, Mother 1 had no history of metabolic decompensation. Mother 2 had no reported history of fasting intolerance or metabolic decompensation and neither mothers reported a history of serious illness, surgery or hospitalization. It is possible that the self-initiated regimen of Mother 1 helped to prevent more serious symptoms of MCADD from materializing. However, apart from Mother 1's strategy of eating frequent meals, it is not immediately apparent how our patients reached adulthood without experiencing severe symptoms or a life-threatening decompensation. Data derived from newborn screening has revealed a higher frequency and greater genetic variability of MCADD than previously anticipated based on studies of infants ascertained clinically [23–25]. Additionally, the correlation between genotype and phenotype for MCADD is not clear and can range from sudden infant death to individuals who are asymptomatic, even within the same family [23–28]. It is hypothesized that various gene interactions, idiosyncratic thresholds for fasting and catabolism and molecular regulatory elements may be involved in determining who becomes symptomatic [23,27,29]. Additional research in this area will be necessary to further elucidate these complex interactions. Although our maternal patients were fortunate to escape serious health consequences throughout their lives, the risk of sudden death remained. The literature has revealed many cases of MCADD that were ascertained in adulthood, often with fatal results [30–35]. In a recent review, Lang examined data from fourteen individuals affected with MCADD who were ascertained in adulthood. Analysis revealed a 50% mortality rate in acutely presenting cases and a 29% mortality rate overall [36]. This finding underscores the fact that even if an individual is fortunate enough to escape a metabolic crisis early in life, the risk of sudden, fatal metabolic decompensation from MCADD still remains. Overall, the ability of expanded newborn screening to provide a non-emergent method of identifying mothers at-risk serves as an unanticipated, but invaluable ancillary benefit to generations of mothers to come. MCADD can now be added to the ever-expanding list of maternal inborn errors of metabolism identifiable through abnormal newborn screening when maternal urine organic acid analysis is included in the confirmatory testing process. Acknowledgments The authors wish to thank the Commission for Families and Children of Orange County for their support. We would also like to thank Denise Salazar, Ph.D., DABMG and Rajesh Sharma, Ph.D., DABMG of Quest Diagnostics Nichols Institute who participated in the sign out of the patients' confirmatory testing results. References [1] Y. Matsubara, J.P. Kraus, T.L. Yang-Feng, U. Francke, L.E. Rosenberg, K. Tanaka, Molecular cloning of cDNAs encoding rat and human medium-chain acyl-CoA dehydrogenase and assignment of the gene to human chromosome 1, Proc. Natl. Acad. Sci. 83 (1986) 6543–6547. [2] D.P. Kelly, J.J. Kim, J.J. Billadello, B.E. Hainline, T.W. Chu, A.W. Strauss, Nucleotide sequence of medium-chain acyl-CoA dehydrogenase mRNA and its expression in enzyme-deficient human tissue, Proc. Natl Acad. Sci. 84 (1987) 4068–4072. [3] A.K. Iafolla, R.J. Thompson Jr., C.R. Roe, Medium-chain acyl-coenzyme A dehydrogenase deficiency: clinical course in 120 affected children, J. Pediatr. 124 (1994) 409–415. [4] P. Rinaldo, H.R. Yoon, C. Yu, K. Raymond, C. Tiozzo, G. Giordano, Sudden and unexpected neonatal death: a protocol for the postmortem diagnosis of fatty acid oxidation disorders, Semin. Perinatol. 23 (1999) 204–210. [5] C.R. Roe, J. Ding, Mitochondrial fatty acid oxidation disorders, in: C.R. Scriver, A.L. Beaudet, W.S. Sly, D. Valle (Eds.), The Metabolic & Molecular Bases of Inherited Disease, McGraw-Hill, New York, 2001, pp. 2297–2326. [6] A. Schulze, M. Lindner, D. Kohlmüller, K. Olgemöller, E. Mayatepek, G.F. Hoffmann, Expanded newborn screening for inborn errors of metabolism by electrospray ionization-tandem mass spectrometry: results, outcome, and implications, Pediatrics 111 (2003) 1399–1406.
[7] B. Wilcken, V. Wiley, J. Hammond, K. Carpenter, Screening newborns for inborn errors of metabolism by tandem mass spectrometry, New Eng. J. Med. 348 (2003) 2304–2312. [8] J.L. Van Hove, W. Zhang, S.G. Kahler, C.R. Roe, Y.T. Chen, N. Terada, D.H. Chace, A.K. Iafolla, J.H. Ding, D.S. Millington, Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency: diagnosis by acylcarnitine analysis in blood, Am. J. Hum. Genet. 52 (1993) 958–966. [9] P.T. Clayton, M. Doig, S. Ghafari, C. Meaney, C. Taylor, J.V. Leonard, M. Morris, A.W. Johnson, Screening for medium chain acyl-CoA dehydrogenase deficiency using electrospray ionisation tandem mass spectrometry, Arch. Dis. Child. 79 (1998) 109–115. [10] K.M. Gibson, M.J. Bennett, E.W. Naylor, D.H. Morton, 3-Methylcrotonyl-coenzyme A carboxylase deficiency in Amish/Mennonite adults identified by detection of increased acylcarnitines in blood spots of their children, J. Pediatr. 132 (1998) 519–523. [11] W.L. Nyhan, M. Willis, B.A. Barshop, J. Gangoiti, Positive newborn screen in the biochemically normal infant of a mother with treated holocarboxylase synthetase deficiency, J. Inherit. Metab. Dis. (Apr 11 2009). [12] S. Vijay, A. Patterson, S. Olpin, M.J. Henderson, S. Clark, C. Day, G. Savill, J.H. Walter, Carnitine transporter defect: diagnosis in asymptomatic adult women following analysis of acylcarnitines in their newborn infants, J. Inherit. Metab. Dis. 29 (2006) 627–630. [13] L.A. Schimmenti, E.A. Crombez, B.C. Schwahn, B.A. Heese, T.C. Wood, R.J. Schroer, K. Bentler, S. Cederbaum, K. Sarafoglou, M. McMann, P. Rinaldo, D. Matern, C.A. di San Filippo, M. Pasquali, S.A. Berry, N. Longo, Expanded newborn screening identifies maternal primary carnitine deficiency, Mol. Genet. Metab. 90 (2007) 441–445. [14] A.W. El-Hattab, F.Y. Li, J. Shen, B.R. Powell, E.V. Bawle, D.J. Adams, E. Wahl, J.A. Kobori, B. Graham, F. Scaglia, L.J. Wong, Maternal systemic primary carnitine deficiency uncovered by newborn screening: clinical, biochemical, and molecular aspects, Genet. Med. 12 (2010) 19–24. [15] N.C. Lee, N. Leung-Sang Tang, Y.H. Chien, C.A. Chen, S.J. Lin, P.C. Chiu, A.C. Huang, W.L. Hwu, Diagnoses of newborns and mothers with carnitine uptake defects through newborn screening, Mol. Genet. Metab. 100 (2010) 46–50. [16] E.A. Crombez, S.D. Cederbaum, E. Spector, E. Chan, D. Salazar, J. Neidich, S. Goodman, Maternal glutaric acidemia, type I identified by newborn screening, Mol. Genet. Metab. 94 (2008) 132–134. [17] H.J. Lin, J.A. Neidich, D. Salazar, E. Thomas-Johnson, B.F. Ferreira, A.M. Kwong, A.M. Lin, A.J. Jonas, S. Levine, F. Lorey, D.S. Rosenblatt, Asymptomatic maternal combined homocystinuria and methylmalonic aciduria (cblC) detected through low carnitine levels on newborn screening, J. Pediatr. 155 (2009) 924–927. [18] Y. Matsubara, K. Narisawa, S. Miyabayashi, K. Tada, P.M. Coates, Molecular lesion in patients with medium-chain acyl-CoA dehydrogenase deficiency, Lancet 335 (1990) 1589. [19] I. Yokota, Y. Indo, P.M. Coates, K. Tanaka, Molecular basis of medium chain acylcoenzyme A dehydrogenase deficiency. An A to G transition at position 985 that causes a lysine-304 to glutamate substitution in the mature protein is the single prevalent mutation, J. Clin. Invest. 86 (1990) 1000–1003. [20] D.P. Kelly, A.J. Whelan, M.L. Ogden, R. Alpers, Z.F. Zhang, G. Bellus, N. Gregersen, L. Dorland, A.W. Strauss, Molecular characterization of inherited medium-chain acyl-CoA dehydrogenase deficiency, Proc. Natl Acad. Sci. USA 87 (1990) 9236–9240. [21] J.H. Ding, C.R. Roe, A.K. Iafolla, Y.T. Chen, Medium-chain acyl-coenzyme A dehydrogenase deficiency and sudden infant death, N. Engl. J. Med. 325 (1991) 61–62. [22] I. Yokota, T. Saijo, J. Vockley, K. Tanaka, Impaired tetramer assembly of variant medium-chain acyl-coenzyme A dehydrogenase with a glutamate or aspartate substitution for lysine 304 causing instability of the protein, J. Biol. Chem. 267 (1992) 26004–26010. [23] E.M. Maier, S.W. Gersting, K.F. Kemter, J.M. Jank, M. Reindl, D.D. Messing, M.S. Truger, C.P. Sommerhoff, A.C. Muntau, Protein misfolding is the molecular mechanism underlying MCADD identified in newborn screening, Hum. Mol. Genet. 18 (2009) 1612–1623. [24] E.M. Maier, B. Liebl, W. Röschinger, U. Nennstiel-Ratzel, R. Fingerhut, B. Olgemöller, U. Busch, N. Krone, R.v. Kries, A.A. Roscher, Population spectrum of ACADM genotypes correlated to biochemical phenotypes in newborn screening for medium-chain acyl-CoA dehydrogenase deficiency, Hum. Mutat. 25 (2005) 443–452. [25] B.S. Andresen, S.F. Dobrowolski, L. O'Reilly, J. Muenzer, S.E. McCandless, D.M. Frazier, S. Udvari, P. Bross, I. Knudsen, R. Banas, D.H. Chace, P. Engel, E.W. Naylor, N. Gregersen, Medium-chain acyl-CoA dehydrogenase (MCAD) mutations identified by MS/MS-based prospective screening of newborns differ from those observed in patients with clinical symptoms: identification and characterization of a new, prevalent mutation that results in mild MCAD deficiency, Am. J. Hum. Genet. 68 (2001) 1408–1418. [26] B.S. Andresen, P. Bross, S. Udvari, J. Kirk, G. Gray, S. Kmoch, N. Chamolex, I. Knudsen, V. Winter, B. Wilcken, I. Yokota, K. Hart, S. Packman, J.P. Harpey, J.M. Saudubray, D.E. Hale, L. Bolund, S. Kølvraa, N. Gregersen, The molecular basis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency in compound heterozygous patients: is there correlation between genotype and phenotype? Hum. Mol. Genet. 5 (1997) 695–707. [27] S.H. Korman, A. Gutman, R. Brooks, T. Sinnathamby, N. Gregersen, B.S. Andresen, Homozygosity for a severe novel medium-chain acyl-CoA dehydrogenase (MCAD) mutation IVS3-1G N C that leads to introduction of a premature termination codon by complete missplicing of the MCAD mRNA and is associated
K.B. Leydiker et al. / Molecular Genetics and Metabolism 103 (2011) 92–95
[28]
[29]
[30]
[31]
with phenotypic diversity ranging from sudden neonatal death to asymptomatic status, Mol. Genet. Metab. 82 (2004) 121–129. J. Purevsuren, H. Kobayashi, Y. Hasegawa, Y. Mushimoto, H. Li, S. Fukuda, Y. Shigematsu, T. Fukao, S. Yamaguchi, A novel molecular aspect of Japanese patients with medium-chain acyl-CoA dehydrogenase deficiency (MCADD): c. 449– 452delCTGA is a common mutation in Japanese patients with MCADD, Mol. Genet. Metab. 96 (2009) 77–79. K.B. Nielsen, S. Sørensen, L. Cartegni, T.J. Corydon, T.K. Doktor, L.D. Schroeder, L.S. Reinert, O. Elpeleg, A.R. Krainer, N. Gregersen, J. Kjems, B.S. Andresen, Seemingly neutral polymorphic variants may confer immunity to splicing-inactivitating mutations: a synonymous SNP in exon 5 of MCAD protects from deleterious mutations in a flaking exonic splicing enhancer, Am. J. Hum. Genet. 80 (2007) 416–432. K. Raymond, A.E. Bale, C.A. Barnes, P. Rinaldo, Medium-chain acyl-CoA dehydrogenase deficiency: sudden and unexpected death of a 45 year old woman, Genet. Med. 1 (1999) 293–294. G.W. Wilhelm, Sudden death in a young woman from medium chain acyl-coenzyme A dehydrogenase (MCAD) deficiency, J. Emerg. Med. 30 (2005) 291–294.
95
[32] S.J. Mayell, L. Edwards, F.E. Reynolds, A.B. Chakrapani, Late presentation of mediumchain acyl-CoA dehydrogenase deficiency, J. Inherit. Metab. Dis. 30 (2007) 104. [33] F. Feillet, G. Steinmann, C. Vianey-Saban, C. de Chillou, N. Sadoul, E. Lefebvre, M. Vidailhet, P.E. Bollaert, Adult presentation of MCAD deficiency revealed by coma and severe arrhythmias, Intensive Care Med. 29 (2003) 1594–1597. [34] H. Losty, G. Melville-Thomas, R. Pollitt, S. Davies, Medium-chain acyl-CoA dehydrogenase deficiency, sudden unexpected death in a 23-year-old woman, J. Inherit. Metab. Dis. 24 (2001) 68. [35] W. Ruitenbeek, P.J.E. Poels, D.M. Turnbull, B. Garavaglia, R.A. Chalmers, R.W. Taylor, F.J.M. Gabreels, Rhabdomyolysis and acute encephalopathy in late onset medium chain acyl-CoA dehydrogenase deficiency, J. Neurol. Neurosurg. Psychiatry 58 (1995) 209–214. [36] T.F. Lang, Adult presentations of medium-chain acyl-CoA dehydrogenase deficiency (MCADD), J. Inherit. Metab. Dis. 32 (2009) 675–683.
Internet Reference [37] http://gmdi.org/Resources/NutritionGuidelines/MCADDGuidelines8Edited by Dianne M. Frazier, PhD, MPH, RD updated 2/10/08; accessed 12/17/10.
