For Kay, her motivation to bring Max the Monkey to life stemmed from a combination of typical toddler picky eating and a lack of the vocabulary to discuss MCADD in a way that would be accessible to her young sons.
"There are dozens of books telling kids about moving from a crib to a bed or learning how to use the potty." However, there wasn't yet a single kid-friendly book about MCADD, so Kay set out to create one.
Indeed, before the advent of NBS using LC-MS/MS, the clinically ascertained incidence of MCADD was roughly 1: 30,000 to 1: 135,000 [13,33], while population-based NBS is revealing a much higher incidence of MCADD in newborns, ranging from 1 in 10,000 to 1 in 20,000 in different populations [19, 20, 33-37].
MCADD undiagnosed individuals are asymptomatic until an episode of increased energy demand and fasting occurs, resulting in metabolic crisis or even sudden death.
Insinga and colleagues (2002) reported costs for confirmatory testing for MCADD, inflated to 2005 dollars, as $1,631.
From the various sources cited and for purposes of this study, confirmatory testing for MCADD, including laboratory tests and clinical evaluation, is approximately $1,560.
Six centers participating in the UK Collaborative Study of MCADD
 screened approximately half the births in the UK (approximately 350 000 births per year).
"We'd never heard of MCADD
before Thomas was diagnosed," said Sue.
Advocates may say: "If Baby A had only had a fifty-dollar screening test for MCADD
, his life could have been saved.
As an example, we investigated this approach for MCADD
(12) using acylcarnitine concentrations measured by TMS for newborn screening and their arithmetic combinations.
(13) Even with MCADD
, population screening studies suggest there are less severe genetic variants for which the impact of early detection and treatment is uncertain.
 Nonstandard abbreviations: IEM, inborn error(s) of metabolism; GC-MS, gas chromatography-mass spectrometry; ESI, electrospray ionization; TMS, tandem mass spectrometry; MRM, multiple reaction monitoring; OMIM, Online Mendelian Inheritance in Man accession number; THCA, tetrahydroxycholestanoic acid; ASA, argininosuccinate; and MCADD
, medium-chain acyl-CoA dehydrogenase deficiency.