Ex vivo proton spectroscopy (¹H‐NMR) analysis of inborn errors of metabolism: Automatic and computer‐assisted analyses

Abstract

There are about 1500 genetic metabolic diseases. A small number of treatable diseases are diagnosed by newborn screening programs, which are continually being developed. However, most diseases can only be diagnosed based on clinical symptoms or metabolic findings. The main biological fluids used are urine, plasma and, in special situations, cerebrospinal fluid. In contrast to commonly used methods such as gas chromatography and high performance liquid chromatography mass spectrometry, ex vivo proton spectroscopy (1H‐NMR) is not yet used in routine clinical practice, although it has been recommended for more than 30 years. Automatic analysis and improved NMR technology have also expanded the applications used for the diagnosis of inborn errors of metabolism. We provide a mini‐overview of typical applications, especially in urine but also in plasma, used to diagnose common but also rare genetic metabolic diseases with 1H‐NMR. The use of computer‐assisted diagnostic suggestions can facilitate interpretation of the profiles. In a proof of principle, to date, 182 reports of 59 different diseases and 500 reports of healthy children are stored. The percentage of correct automatic diagnoses was 74%. Using the same 1H‐NMR profile‐targeted analysis, it is possible to apply an untargeted approach that distinguishes profile differences from healthy individuals. Thus, additional conditions such as lysosomal storage diseases or drug interferences are detectable. Furthermore, because 1H‐NMR is highly reproducible and can detect a variety of different substance categories, the metabolomic approach is suitable for monitoring patient treatment and revealing additional factors such as nutrition and microbiome metabolism. Besides the progress in analytical techniques, a multiomics approach is most effective to combine metabolomics with, for example, whole exome sequencing, to also diagnose patients with nondetectable metabolic abnormalities in biological fluids. In this mini review we also provide our own data to demonstrate the role of NMR in a multiomics platform in the field of inborn errors of metabolism.

Phenylketonuria (PKU) Urinary Metabolomic Phenotype Is Defined by Genotype and Metabolite Imbalance: Results in 51 Early Treated Patients Using Ex Vivo 1H-NMR Analysis

“…The mixture was homogenized, and 0.6 mL was transferred to a 5 mm NMR tube for analysis and placed in a cooled sample changer. Samples were then measured, in full automation and according to standard procedures, using a Bruker IVDr System, as previously described [ 29 , 68 ].…”

Need and Challenges in Establishing Newborn Screening Programs for Inherited Metabolic Disorders in Developing Countries

“…[ 56 ] Furthermore, it is highly reproducible technique and can detect several biological substances, hence, this approach is suitable for monitoring patient treatment and revealing additional factors such as nutrition and microbiome metabolism. [ 57 ]…”

“…[9,71] Hence, the overall primary requirements and benefits of NBS program are summarized in Figure 2. Moreover, overall usage of each technique in NBS, advantages, and disadvantages [57] are listed in Table 2 with more detail.…”