Inborn Errors of Metabolism in Children with Unexplained Developmental Delay in Misan, Iraq

Objectives

We sought to determine the prevalence of inborn errors of metabolism (IEM) in children with unexplained developmental delay and their types.

Methods

We conducted a cross-sectional study in Misan, Iraq, over a period of one year. A total of 112 infants with unexplained developmental delay were included in the study, and the required information was taken from their parents by direct interview. Tandem mass spectrometry (MS/MS) was done in collaboration with MedLabs’ Referral Laboratory in Amman, Jordan.

Results

Twenty (17.9%) cases had abnormal MS/MS. Disorders of amino acid metabolism represented the majority of IEM (10 cases) in which phenylketonuria and maple syrup urine disease were the most common (found in five cases each). Organic and fatty acid metabolisms were found in five and two cases, respectively. Most cases of IEM had a positive family history and consanguinity, however, family history was the only significant factor (p < 0.001).

Conclusions

A high rate of IEM was detected in children with unexplained developmental delay in Misan. A high clinical suspicion with positive family history and consanguinity supported by the MS/MS results played an essential role in the diagnosis. However, implementation of newborn screening is essential for early diagnosis and to determine appropriate therapy in newborns with IEM in Iraq generally and in Misan in particular.

An Introduction to Pharmacotherapy for Inborn Errors of Metabolism

Inborn errors of metabolism comprise a wide array of diseases and complications in the pediatric patient. The rarity of these disorders limits the ability to conduct and review robust literature regarding the disease states, mechanisms of dysfunction, treatments, and outcomes. Often, treatment plans will be based on the pathophysiology associated with the disorder and theoretical agents that may be involved in the metabolic process. Medication therapies usually consist of natural or herbal products. Established efficacious pediatric doses for these products are difficult to find in tertiary resources, and adverse effects are routinely limited to single case reports. This review article attempts to summarize some of the more common inborn errors of metabolism in a manner that is applicable to pharmacists who will provide care for these patients.

Neuroimaging Findings of Organic Acidemias and Aminoacidopathies

Although individual cases of inherited metabolic disorders are rare, overall they account for a substantial number of disorders affecting the central nervous system. Organic acidemias and aminoacidopathies include a variety of inborn errors of metabolism that are caused by defects in the intermediary metabolic pathways of carbohydrates, amino acids, and fatty acid oxidation. These defects can lead to the abnormal accumulation of organic acids and amino acids in multiple organs, including the brain. Early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurologic impairments or death. Neuroimaging findings can be nonspecific, and metabolism- and genetics-based laboratory investigations are needed to confirm the diagnosis. However, neuroimaging has a key role in guiding the diagnostic workup. The findings at conventional and advanced magnetic resonance imaging may suggest the correct diagnosis, help narrow the differential diagnosis, and consequently facilitate early initiation of targeted metabolism- and genetics-based laboratory investigations and treatment. Neuroimaging may be especially helpful for distinguishing organic acidemias and aminoacidopathies from other more common diseases with similar manifestations, such as hypoxic-ischemic injury and neonatal sepsis. Therefore, it is important that radiologists, neuroradiologists, pediatric neuroradiologists, and clinicians are familiar with the neuroimaging findings of organic acidemias and aminoacidopathies. ^©RSNA, 2018.