Inborn errors of metabolism for the diagnostic radiologist

A preliminary investigation of amino acid and acylcarnitine levels in neonates from the Tibet autonomous

Background: The purpose of the study was to investigate the levels of amino acids and acylcarnitines in newborns of the Tibet Autonomous Region for the first time and to provide an experimental basis for the diagnosis of genetic metabolic diseases. Methods: We detected concentrations of 43 kinds of amino acids, acylcarnitines and succinylacetone in the dried blood spots of 18482 newborns using liquid chromatography tandem mass spectrometry and diagnose the case by gene sequencing. We compared the indexes between Tibet and our lab, where most data come from an inland area and Han Chinese people. Then we compared amino acid and acylcarnitine levels of seven regions in Tibet and explored their impact factors. Results: We described the levels of amino acids and acylcarnitines in Tibet newborns using 95% confidence intervals. The distribution of amino acid and acylcarnitines were different in Tibet. Conclusion: This study has contributed to filling in the blanks of Tibet newborn screening, which should be considered in the newborn metabolic disease screening in this area.

Niemann-Pick disease type B: HRCT assessment of pulmonary involvement

OBJECTIVE

To analyze HRCT findings in patients with Niemann-Pick disease (NPD) type B, in order to determine the frequency of HRCT patterns and their distribution in the lung parenchyma, as well as the most common clinical characteristics.

METHODS

We studied 13 patients (3 males and 10 females) aged 5 to 56 years. HRCT images were independently evaluated by two observers, and disagreements were resolved by consensus. The inclusion criteria were presence of abnormal HRCT findings and diagnosis of NPD type B confirmed by histopathological examination of a bone marrow, lung, or liver biopsy specimen.

RESULTS

The most common clinical findings were hepatosplenomegaly and mild to moderate dyspnea. The most common HRCT patterns were smooth interlobular septal thickening and ground-glass opacities, which were both present in all patients. Intralobular lines were present in 12 patients (92.3%). A crazy-paving pattern was observed in 5 patients (38.4%), and areas of air trapping were identified in only 1 case (7.6%). Pulmonary involvement was bilateral in all cases, with the most affected area being the lower lung zone.

CONCLUSIONS

Smooth interlobular septal thickening, with or without associated ground-glass opacities, in patients with hepatosplenomegaly is the most common finding in NPD type B.

Deconstructing Black Swans: An Introductory Approach to Inherited Metabolic Disorders in the Neonate

BACKGROUND

Inherited metabolic disorders (IMDs) are individually rare but collectively common disorders that frequently require rapid or urgent therapy.

PURPOSE

This article provides a generalized approach to IMDs, as well as some investigations and safe therapies that may be initiated pending the metabolic consult.

METHODS/SEARCH STRATEGY

An overview of the research supporting management strategies is provided. In addition, the newborn metabolic screen is reviewed.

FINDINGS/RESULTS

Caring for infants with IMDs can seem difficult because each of the types is rarely seen; however, collectively the management can be seen as similar.

IMPLICATIONS FOR PRACTICE

When an IMD is suspected, a metabolic specialist should be consulted for expert advice regarding appropriate laboratory investigations and management. Because rapid intervention of IMDs before the onset of symptoms may prevent future irreversible sequelae, each abnormal newborn screen must be addressed promptly.

IMPLICATIONS FOR RESEARCH

Management can be difficult. Research in this area is limited and can be difficult without multisite coordination since sample sizes of any significance are difficult to achieve.

Atypical imaging findings in the setting of methylmalonic acidemia in an infant

Classically, methylmalonic acidemia (MMA) is characterized on imaging by abnormalities in the basal ganglia, specifically the globus pallidi, as well as occasional signs of delayed maturation. We report a case of MMA in which abnormal signal and diffusion restriction occurred in the subcortical white matter, sparing the classically involved globus pallidi, a situation that has not been previously reported in the literature. This report demonstrates that diffusion abnormality can be seen in the white matter in MMA, in the absence of basal ganglia involvement, and that MMA may be considered when the diagnosis of metabolic acidemias is raised.

The dentate nucleus in children: normal development and patterns of disease

The dentate nuclei lie deep within the cerebellum and play a vital role in the pathways involved in fine motor control and coordination. They are susceptible to a variety of diseases. Some pathological processes preferentially affect the dentate nuclei, while concomitant basal ganglia or white matter involvement can be a striking finding in others. A familiarity with the normal appearance of the dentate nuclei at different ages in combination with the radiological distribution of pathology in the brain allows the paediatric radiologist to develop a logical approach to the interpretation of MR imaging of these deep cerebellar nuclei. In this article we review the normal appearance and MR features of the dentate nuclei, including changes that are seen with myelination. We describe the specific imaging characteristics of childhood diseases that involve the dentate nuclei, and develop a systematic approach to the differential diagnosis of dentate nucleus abnormalities on MR imaging.

CARNITINE HOMEOSTASIS, MITOCHONDRIAL FUNCTION, AND CARDIOVASCULAR DISEASE

Carnitines are involved in mitochondrial transport of fatty acids and are of critical importance for maintaining normal mitochondrial function. This review summarizes recent experimental and clinical studies showing that mitochondrial dysfunction secondary to a disruption of carnitine homeostasis may play a role in decreased NO signaling and the development of endothelial dysfunction. Future challenges include development of agents that can positively modulate L-carnitine homeostasis which may have high therapeutic potential.