Diagnostic challenges of aminoacidopathies and organic acidemias in a developing country: A twelve-year experience

Spectrum of Organic Aciduria Diseases in Tunisia: A 35-year Retrospective Study

Background

Organic aciduria diseases (OADs) occur worldwide, with differences in prevalence and patterns between populations.

Objectives

To describe the spectrum of OADs identified in Tunisia over a 35-years period.

Materials and Methods

This retrospective study included patients who were diagnosed with OADs between 1987 and 2022 in the Laboratory of Biochemistry, Rabta Hospital, Tunisia. Organic acids were analyzed using gas chromatography-mass spectrometry.

Results

A total of 30,670 urine samples were analyzed for OADs, of which 471 were positive for OADs. The estimated incidence of OADs in Tunisia was 6.78 per 100,000 live births. Methylmalonic (n = 146) and propionic (n = 90) acidurias were the most common OADs (estimated incidence: 2.10 and 1.30 per 100,000 live births, respectively). There were 54 cases of L-2-hydroxyglutatric acidurias and 30 cases of pyroglutamic acidurias, which makes it one of the highest in the world. The main clinical features were hypotonia (65%) and feeding difficulties (41%). Age at diagnosis was highly variable, ranging from 1 day to 49 years. Only 27% of the patients were diagnosed within the first month of life. The prevalence of OADs was highest in the Center-East and Southeast regions.

Conclusions

In Tunisia, OADs are relatively frequent, but there are shortcomings regarding the diagnosis of these disorders. The frequency and health/social impact of these disorders warrant the need for implementing newborn screening programs and suitable patient management.

Recomendaciones de manejo de la hiperamonemia en neonatos

La hiperamonemia se define como el aumento de las concentraciones de amonio en el plasma, de forma aguda o crónica. Frecuentemente, se presenta en diversos tipos de errores innatos del metabolismo, enfermedades que deben diagnosticarse y manejarse de manera inmediata y adecuada, debido a que el retraso en su manejo genera secuelas neurológicas graves y permanentes, así como desenlaces fatales. El objetivo del artículo es aportar herramientas al clínico para la sospecha, el abordaje diagnóstico y el manejo del recién nacido con hiperamonemia primaria, teniendo en cuenta la correlación entre fisiopatología, etiología, aproximación clínica y de laboratorio, así como recomendaciones de manejo farmacológico y no farmacológico.

Challenges of genetic diagnosis of inborn errors of metabolism in a major tertiary care center in Lebanon

Background: Inborn errors of metabolism are rare genetic disorders; however, these are prevalent in countries with high consanguinity rates, like Lebanon. Patients are suspected, based on a combination of clinical and biochemical features; however, the final confirmation relies on genetic testing. Using next generation sequencing, as a new genetic investigational tool, carries several challenges for the physician, the geneticist, and the families. Methods: In this retrospective study, we analyzed the clinical, biochemical, and genetic profile of inborn errors of metabolism suspected patients, seen at a major tertiary care center in Lebanon, between 2015 and 2018. Genetic testing was performed using next generation sequencing. Genotype-phenotype correlation and diagnostic yield of each testing modality were studied. Results: Out of 211 patients genetically tested, 126 were suspected to have an inborn error of metabolism. The diagnostic yield of next generation sequencing reached 64.3%. Single gene testing was requested in 53%, whole exome sequencing in 36% and gene panels in 10%. Aminoacid disorders were mostly diagnosed followed by storage disorders, organic acidemias and mitochondrial diseases. Targeted testing was performed in 77% of aminoacid and organic acid disorders and half of suspected storage disorders. Single gene sequencing was positive in 75%, whereas whole exome sequencing diagnostic yield for complex cases, like mitochondrial disorders, reached 49%. Good clinical and biochemical correlation allowed the interpretation of variants of unknown significance and negative mutations as well as therapeutic management of most patients. Conclusion: Tailoring the choice of test modality, by next generation sequencing, to the category of suspected inborn errors of metabolism may lead to rapid diagnosis, shortcutting the cost of repeated testing. Whole exome sequencing as a first-tier investigation may be considered mainly for suspected mitochondrial diseases, whereas targeted sequencing can be offered upon suspicion of a specific enzyme deficiency. Timing and modality of gene test remain challenging, in view of the cost incurred by families.

Utilizing augmented artificial intelligence for aminoacidopathies using collaborative laboratory integrated reporting- A cross-sectional study

Introduction

Plasma amino acids profiling can aid in the screening and diagnosis of aminoacidopathies. The goal of the current study was to analyze and report the metabolic profiles of plasma amino acid (PAA) and additionally to compare PAA-reference intervals (RI) from Pakistan with more countries utilizing Clinical Laboratory Integrated Reports (CLIR).

Methods

This was a cross sectional prospective single center study. Twenty-two amino acids were analyzed in each sample received for one year at the clinical laboratory. Data was divided into reference and case data files after interpretation by a team of pathologists and technologists. All PAA samples were analyzed using ion-exchange high-performance chromatography. The CLIR application of Amino Acid in Plasma (AAQP) was used for statistical analysis for both data sets and post-analytical interpretive tools using a single condition tool was applied.

Result

The majority of 92% (n = 1913) of PAA profiles out of the total 2081 tests run were non-diagnostic; the PAA values were within the age-specific RI. The PAA median was in close comparison close to the 50th percentile of reference data available in CLIR software. Out of the total 2081 tests run, one hundred and sixty-eight had abnormal PAA levels; 27.38% were labeled as non-fasting samples, and the main aminoacidopathies identified were Phenylketonuria and Maple Syrup Urine Disorder.

Conclusion

An agreement of >95% was observed between the reporting done by the pathologists and technologists’ team and then after the application of CLIR. Augmented artificial intelligence using CLIR can improve the accuracy of reporting rare aminoacidopathies in a developing country like ours.

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Plasma amino acids helps in diagnosing and monitoring of various aminoacidopathies.

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Few aminoacidopathies present with a grossly abnormal investigation profile, with few diseases having subtle deviations.

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Their is 98% concordance of diagnosis concordance of diagnosis of aminoacidopathies between our lab and CLIR.

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CLIR tools can be utilized in a newborn screening program for screening and diagnosis in future.

Inherited metabolic disorders in a cohort of Egyptian children

Background

Inborn errors of metabolism (IEMs) represent a special challenge in pediatric practice. Despite the unquestionable clinical significance of newborn screening, it just offers a snapshot of an extremely minor subgroup of metabolic disorders. So, it is crucial to use multiple techniques for accurate diagnosis of a wider spectrum of IEMs early in infancy to prevent overwhelming irreversible neurological complications in a cohort of high-risk Egyptian pediatrics. This study included four thousand and eighty suspected IEMs patients. They were referred to the Chromatography Unit, Clinical Biochemistry and Molecular Diagnostics Laboratories, National Liver Institute (NLI) for laboratory assessment in the period from March 2016 to November 2020. Separation of amino acids and acylcarnitines using tandem mass spectrometry (LC/MS) and organic acids using gas chromatography mass spectrometry (GC/MS) was done.

Results

Three hundred and twenty (320/4080, 7.8%) patients were diagnosed with IEMs. The following disorders were identified: organic acidopathies—200 (62.5%) including methylmalonic acidemia (MMA) (48/320, 15%), glutaric academia (GA) (40/320, 12, 5%), propionic acidemia (PA), (32/320, 10%), isovaleric acidemia (IVA) (40/320, 12.5%), methylcrotonyl glyceinuria (16/320, 5%), and orotic acidemia (24/320, 7.5%); amino acidopathies—80 (25%) including maple syrup urine disease (MSUD) (32/320, 10%), phenylketonuria (24/320, 7.5%), homocystinuria (16/320, 5%), and nonketotic hyperglycinemia (8/320, 2.5%) in addition to fatty acid disorders (FAO): 24 (7.5%) and lactic academia (LA), 16 (5%).

Conclusion

Early detection of IEMs by rapid non-invasive techniques. LC/MS and GC/MS. is a crucial process for early diagnosis of different types of IEMs to install therapeutic clue in a group of high-risk Egyptian pediatrics for proper treatment and better outcome

Prevalence of methylmalonic acidemia among newborns and the clinical-suspected population: a meta-analyse

IMPORTANCE

Knowing the scale of rare inborn errors is important for screening and resource allocation. Evidence on the prevalence of methylmalonic acidemia (MMA) among newborns and the clinical-suspected population from large-scale screening programs needs to be systematically synthesized.

OBJECTIVE

To estimate the worldwide prevalence of MMA for newborns and the clinical-suspected population and explore the differences in different regions, periods, and diagnostic technologies.

DATA SOURCES

MEDLINE, Embase, CRD, Cochrane Library, Scopus, CINAHL, and PROSPERO. Study Selection: All studies reporting the epidemiology characteristics of MMA were selected.

DATA EXTRACTION AND SYNTHESIS

Characteristics of study, subjects, and epidemiology were extracted, random-effect models were used for meta-analyses.

MAIN OUTCOME AND MEASURE

Pooled prevalence of MMA.

RESULTS

This study included 111 studies. The pooled prevalence of MMA worldwide was 1.14 per 100,000 newborns (1516/190,229,777 newborns, 95% CI: 0.99-1.29) and 652.11 per 100,000 clinical-suspected patients (1360/4,805,665 clinical-suspected individuals, CI: 544.14-760.07). Asia and Africa got a higher pooled prevalence of MMA. The prevalence of MMA in newborns increased through the years, while that in the clinical-suspected population decreased. Collecting blood ≥ 72 h after birth had a higher pooled prevalence of MMA than collecting during 24 h-72 h after birth. The combining-use of MS/MS and GC/MS had a higher pooled prevalence than the single-use of MS/MS or GC/MS. Prevalence of cbl C, mut, cbl B, cbl A, isolated MMA, combined MMA and homocystinuria, vitamin B12-responsive MMA was synthesized.

CONCLUSIONS AND RELEVANCE

Prevalence of MMA among newborns was extremely low, but considerably high in the clinical-suspected population, indicating the need for more efficient newborn screening strategies and closer monitoring of the high-risk population for the early signs of MMA. Asia and Africa should attach importance to the high prevalence of MMA. Further diagnostic tests were recommended for the combining-use vs single-use of MS/MS and GC/MS and for collecting blood after 72 h vs during 24-72 h after birth.

Laboratory practice of organic acid analysis based on gas chromatography–mass spectrometry in China

Objectives

The aim of this study is to investigate the status of laboratory practice of organic acid (OA) analysis using gas chromatography–mass spectrometry in China.

Methods

A survey, investigating details of laboratory practice of OA analysis, was issued on the website of the National Center for Clinical Laboratories of China. Nationwide external quality assessment participating laboratories of OA assay were informed to participate in this survey.

Results

A total of 36 laboratories completed this survey. Most laboratories started OA analysis during 2016–2020. Most (100%) labs reported semi-quantitative results, in which 79.4% of labs adopted the form of the ratio of peak area of OA and quantitative internal standard. Rare labs reported quantitative results. Few labs released reports in three days, most in 5–7 days. The source of control materials varied, 64.5% of labs adapted self-made materials. A total of 43.8% of laboratories directly used reference intervals (RIs) from published literature, 43.8% of laboratories established RIs themselves, but 21.2% of laboratories reported they didn’t verify RIs.

Conclusions

Appropriate supervision for the organic acid assay is needed in the aspect of the turnaround time of reporting results, the establishment validation and verification of reference ranges, and the quantification of results.

Orthopaedic manifestations of glutaric acidemia Type 1

PURPOSE

Glutaric acidemia type 1 (GA1), a rare hereditary metabolic disease caused by biallelic mutations of GCDH, can result in acute or insidious striatal degeneration within the first few years of life. We reviewed the orthopaedic sequelae and management of 114 neurologically injured patients with a confirmed molecular diagnosis of GA1.

METHODS

We performed a retrospective chart review spanning 28 years identifying 114 GA1 patients, most from the Old Order Amish population of Lancaster County, Pennsylvania, who were homozygous for a pathogenic founder variant of GCDH (c.1262C>T). We collected demographics, medical comorbidities, muscle tone patterns, Gross Motor Function Classification System level, gastrostomy tube status, seizure history, inpatient events, orthopaedic diagnoses and operative characteristics.

RESULTS

Over an average follow-up of 4.7 ± 3.4 years, 24 (21%) of 114 patients had musculoskeletal problems requiring orthopaedic consultation. Scoliosis (n = 14), hip dislocation (n = 8/15 hips), hip subluxation (n = 2/three hips), and windswept hip deformity (n = 2) in the spine and hip joint were most common. In total, 35 orthopaedic surgeries were performed in 17 (71%) patients. The most common primary operations were one-stage procedures with proximal femoral varus derotation osteotomy and/or pelvic osteotomy (n = 8/14 hips) for subluxation or dislocation. In all, 11 patients had posterior spinal fusion for severe scoliosis. With the recommended metabolic management, there were no disease-specific complications in this cohort.

CONCLUSIONS

Children with GA1 who have static striatal lesions are at risk for musculoskeletal complications, especially scoliosis and hip dislocation, and appropriate operative management requires consultation with a metabolic specialist with specific considerations for fluid management and nutrition.

LEVEL OF EVIDENCE

IV.

Branched-chain α-ketoacid dehydrogenase deficiency (maple syrup urine disease): Treatment, biomarkers, and outcomes

Over the past three decades, we studied 184 individuals with 174 different molecular variants of branched-chain α-ketoacid dehydrogenase activity, and here delineate essential clinical and biochemical aspects of the maple syrup urine disease (MSUD) phenotype. We collected data about treatment, survival, hospitalization, metabolic control, and liver transplantation from patients with classic (i.e., severe; n = 176), intermediate (n = 6) and intermittent (n = 2) forms of MSUD. A total of 13,589 amino acid profiles were used to analyze leucine tolerance, amino acid homeostasis, estimated cerebral amino acid uptake, quantitative responses to anabolic therapy, and metabolic control after liver transplantation. Standard instruments were used to measure neuropsychiatric outcomes. Despite advances in clinical care, classic MSUD remains a morbid and potentially fatal disorder. Stringent dietary therapy maintains metabolic variables within acceptable limits but is challenging to implement, fails to restore appropriate concentration relationships among circulating amino acids, and does not fully prevent cognitive and psychiatric disabilities. Liver transplantation eliminates the need for a prescription diet and safeguards patients from life-threatening metabolic crises, but is associated with predictable morbidities and does not reverse pre-existing neurological sequelae. There is a critical unmet need for safe and effective disease-modifying therapies for MSUD which can be implemented early in life. The biochemistry and physiology of MSUD and its response to liver transplantation afford key insights into the design of new therapies based on gene replacement or editing.

Detection of some metabolic disorders in suspected neonates admitted at Assiut University Children Hospital

Background

Inborn errors of metabolism are genetically inherited diseases which can lead to accumulation of toxic metabolites in the body. Inborn errors of metabolism have a high morbidity and mortality in neonates. Many inborn errors of metabolism are amenable to treatment with early diagnoses. Till now, more than 500 metabolic disorders have been detected. Although individual metabolic disorders are rare, the incidence of overall metabolic disorders is high.

Results

It was found that 70/200 cases (35 %) had confirmed inborn errors of metabolism, and another 8 cases (4%) suspected to have inborn errors of metabolism; 15/200 (7.5%) cases had mild elevation of phenylalanine level, while 107/200 (53.5%) had another diagnosis rather than metabolic disorders. Urea cycle defect was diagnosed in 20/70 (28.5%), maple syrup urine disease in 18/70 (25.7%), organic acidemia in 15/70 (21.4%), and non-ketotic hyperglycinemia in 1/70 (1.4 %) case. Also, 15/70 (21.4 %) cases had fatty acid oxidation defect. Lastly, one female case (1.4 %) was diagnosed to have disorder of pyrimidine deficiency.

Conclusion

Diagnosis of inborn errors of metabolism was confirmed in 35% of neonates, and 4% was suspected to have metabolic disorders. These results showed that inherited metabolic disorders are not rare. The development of a nationwide screening program for metabolic disorders is mandatory for early detection of these potentially treatable disorders.

Diagnostic contribution of metabolic workup for neonatal inherited metabolic disorders in the absence of expanded newborn screening

Inherited metabolic disorders (IMDs) in neonates are a diagnostic and therapeutic challenge for the neonatologist, with the priority being to rapidly flag the treatable diseases. The objective of this study was to evaluate the contribution of targeted metabolic testing for diagnosing suspected IMDs on the basis of suggestive clinical setting or family history in neonates. We conducted an observational study over five years, from January 1st, 2010 to December 31, 2014 in the neonatal intensive care unit (NICU) at Robert Debré University Hospital, Paris, France. We assessed the number of neonates for whom a metabolic testing was performed, the indication for each metabolic test and the diagnostic yield of this selected metabolic workup for diagnosing an IMD. Metabolic testing comprised at least one of the following testings: plasma, urine or cerebrospinal fluid amino acids, urine organic acids, plasma acylcarnitine profile, and urine mucopolysaccharides and oligosaccharides. 11,301 neonates were admitted at the neonatal ICU during the study period. One hundred and ninety six neonates underwent metabolic testing. Eleven cases of IMDs were diagnosed. This diagnostic approach allowed the diagnosis, treatment and survival of 4 neonates (maple syrup urine disease, propionic acidemia, carnitine-acylcarnitine translocase deficiency and type 1 tyrosinemia). In total, metabolic testing was performed for 1.7% of the total number of neonates admitted in the NICU over the study period. These included 23% finally unaffected neonates with transient abnormalities, 5.6% neonates suffering from an identified IMD, 45.4% neonates suffering from a non-metabolic identified disease and 26% neonates with chronic abnormalities but for whom no final causal diagnosis could be made. In conclusion, as expected, such a metabolic targeted workup allowed the diagnosis of classical neonatal onset IMDs in symptomatic newborns. However, this workup remained normal or unspecific for 94.4% of the tested patients. It allowed excluding an IMD in 68.4% of the tested neonates. In spite of the high rate of normal results, such a strategy seems acceptable due to the severity of the symptoms and the need for immediate treatment when available in neonatal IMDs. However, its cost-effectiveness remains low especially in a clinically targeted population in a country where newborn screening is still unavailable for IMDs except for phenylketonuria in 2019.

Biochemical screening of intellectually disabled and healthy children in Punjab, Pakistan: differences in liver function test and lipid profiles

Objectives: Inborn errors of metabolism (IEMs) are rare genetic disorders. Generally, IEMs are untreatable; however, some IEMs causing intellectual disability are potentially treatable if diagnosed earlier. In this study, levels of some clinically important biochemical parameters in intellectually disabled children suspected for IEMs were tested to see their association with intellectual disability, which could be helpful in preliminary screening. Methods: This comparative cross-sectional observational study was carried out from 2014 to 2017. Blood samples from 800 boys and girls (aged 4-24 years) were collected, of which 391 were healthy (IQ >90) and 409 were intellectually disabled (IQ <70) children with unknown cause. Clinically important (Liver and kidney enzymes etc.) biochemical parameters were analyzed in sera samples using commercial kits on semi-automated clinical chemistry analyzer. Results: Serum analysis showed the levels of ALP (p < 0.00001), ASAT (p = 0.001), ALAT (p = 0.016), albumin (p < 0.001), uric acid (p < 0.001), cholesterol (p < 0.001), triglycerides (p < 0.001), and hemoglobin (p = 0.005) were significantly different between healthy and intellectually disabled children. Conclusion: Changes in the liver function test and lipid profile parameters were significantly different in children with intellectual disability; however, it requires further detailed analysis for complete characterization of these diseases.

Research, diagnosis and education in inborn errors of metabolism in Colombia: 20 years' experience from a reference center

The use of specialized centers has been the main alternative for an appropriate diagnosis, management and follow up of patients affected by inborn errors of metabolism (IEM). These centers facilitate the training of different professionals, as well as the research at basic, translational and clinical levels. Nevertheless, few reports have described the experience of these centers and their local and/or global impact in the study of IEM. In this paper, we describe the experience of a Colombian reference center for the research, diagnosis, training and education on IEM. During the last 20 years, important advances have been achieved in the clinical knowledge of these disorders, as well as in the local availability of several diagnosis tests. Organic acidurias have been the most frequently detected diseases, followed by aminoacidopathies and peroxisomal disorders. Research efforts have been focused in the production of recombinant proteins in microorganisms towards the development of new enzyme replacement therapies, the design of gene therapy vectors and the use of bioinformatics tools for the understanding of IEM. In addition, this center has participated in the education and training of a large number professionals at different levels, which has contributed to increase the knowledge and divulgation of these disorders along the country. Noteworthy, in close collaboration with patient advocacy groups, we have participated in the discussion and construction of initiatives for the inclusion of diagnosis tests and treatments in the health system.

The Prevalence of Phenylketonuria in Arab Countries, Turkey, and Iran: A Systematic Review

Background/Objectives

This paper seeks to identify the prevalence of Phenylketonuria (PKU) in Arab countries, Turkey, and Iran. The study reviewed the existence of comprehensive national newborn screening programs and reported consanguinity rates.

Methods

A computer based literature search was conducted using relevant keywords to retrieve studies conducted on PKU. A total of 34 articles were included. Prevalence was categorized based on the type of screening method used for PKU diagnoses.

Results

The prevalence of classical PKU diagnosed through a comprehensive national newborn screening program ranged from 0.005% to 0.0167%. The highest prevalence was reported in Turkey at 0.0167%, whereas the lowest prevalence was reported in the UAE, 0.005%.

Conclusion

The findings of this review emphasize the need for the establishment of more efficient reporting systems in these countries that would help measure Disability-Adjusted Life Year (DALY) in order to estimate the overall societal burden of PKU.

Aminoacidopathies: Prevalence, Etiology, Screening, and Treatment Options

Inborn errors of metabolism (IEMs) are a group of inherited metabolic disorders which are caused by mutations in the specific genes that lead to impaired proteins or enzymes production. Different metabolic pathways are perturbed due to the deficiency or lack of enzymes. To date, more than 500 IEMs have been reported with most of them being untreatable. However, fortunately 91 such disorders are potentially treatable, if diagnosed at an earlier stage of life. IEMs have been classified into different categories and one class of IEMs, characterized by the physiological disturbances of amino acids is called as aminoacidopathies. Out of 91 treatable IEM, thirteen disorders are amino acid related. Aminoacidopathies can be detected by chromatography and mass spectrometry based analytical techniques (e.g., HPLC, GC-MS, LC-MS/MS) for amino acid level changes, and through genetic assays (e.g., PCR, TaqMan Genotyping, DNA sequencing) at the mutation level in the corresponding genes. Hence, this review is focused to describe thirteen common aminoacidopathies namely: Phenylketonuria (PKU), Maple Syrup Urine Disease (MSUD), Homocystinuria/Methylene Tetrahydrofolate Reductase (MTHFR) deficiency, Tyrosinemia type II, Citrullinemia type I and type II, Argininosuccinic aciduria, Carbamoyl Phosphate Synthetase I (CPS) deficiency, Argininemia (arginase deficiency), Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH) syndrome, N-Acetylglutamate Synthase (NAGS) deficiency, Ornithine Transcarbamylase (OTC) deficiency, and Pyruvate Dehydrogenase (PDH) complex deficiency. Furthermore, the etiology, prevalence and commonly used analytical techniques for screening of aminoacidopathies are briefly described. This information would be helpful to researchers and clinicians especially from developing countries to initiate newborn screening programs for aminoacidopathies.

Long-term outcome of expanded newborn screening at Boston children's hospital: benefits and challenges in defining true disease

INTRODUCTION

There is no universal consensus of the disorders included in newborn screening programs. Few studies so far, mostly short-term, have compared the outcome of disorders detected by expanded newborn screening (ENBS) to the outcome of the same disorders detected clinically.

METHODS

We compared the clinical and neurodevelopmental outcomes in patients with metabolic disorders detected by ENBS, including biotinidase testing, with those detected clinically and followed at the Metabolism Clinic at Boston Children's Hospital.

RESULTS

One hundred eighty-nine patients came to attention from ENBS and 142 were clinically diagnosed. 3-methylcrotonyl-CoA carboxylase, biotinidase, and carnitine deficiencies were exclusively identified by ENBS and medium chain acyl-CoA dehydrogenase (MCADD) and very long chain acyl-CoA dehydrogenase deficiencies (VLCADD) were predominantly identified by ENBS whereas the organic acid disorders more often came to attention clinically. Only 2% of the ENBS-detected cases had clinically severe outcomes compared to 42% of those clinically detected. The mean IQ score was 103 + 17 for the ENBS-detected cases and 77 + 24 for those clinically detected. Those newly included disorders that seem to derive the greatest benefit from ENBS include the fatty acid oxidation disorders, profound biotinidase deficiency, tyrosinemia type 1, and perhaps carnitine deficiency.

CONCLUSION

Although the NBS-identified and clinically-identified cohorts were not completely comparable, this long-term study shows likely substantial improvement overall in the outcome of these metabolic disorders in the NBS infants. Infants with mild disorders and benign variants may represent a significant number of infants identified by ENBS. The future challenge will be to unequivocally differentiate the disorders most benefitting from ENBS and adjust programs accordingly.

Demographic and clinical characteristics of the children with aminoacidopathy in Isfahan Province, Central Iran in 2007-2015

CONTEXT

Aminoacidopathies refer to defects in protein synthesis pathways which result in a range of biochemical disorders and clinical presentations. The enzyme defects in intermediate metabolic pathways lead to accumulation of one or more amino acids or metabolites. Despite higher prevalence rates, screening infants for inherited metabolic disorders is not run in many Middle East countries.

AIM

This research is part of a larger study of inherited metabolic disorders to characterize and measure the prevalence of aminoacidopathies.

SETTINGS AND DESIGN

Cross-sectional study in the population aged 0-17 years old in Isfahan province of Iran, 2007-2015.

SUBJECTS AND METHODS

Demographic characteristics, history of disease, development of clinical condition and socioeconomic status were obtained from interviews as well as patient records of pediatric tertiary referral hospitals and metabolic disorders centers.

STATISTICAL ANALYSIS USED

SPSS qualitative and quantitative analysis.

RESULTS

The incidence rate of aminoacidopathies was derived to be 9/100,000 live births. The frequency of consanguineous marriages in this group of the patients was 89.2%. Of the patients with aminoacidopathies, 76.6% required hospitalization with tyrosinemia having the highest rate overall (>10 times). The most prevalent symptoms in this group of patients were developmental disorders and convulsions while half presented with growth disorders during follow-up. Of the 35.5% patients, who died at various ages, one-third was in the maple syrup urine disease subgroup.

CONCLUSION

Although metabolic disorders are identified as rare diseases, they are more prevalent in the studied population of Isfahan.

Diagnosis and clinical features of organic acidemias: A hospital-based study in a single center in Damascus, Syria

Background: Organic acidemias (OA) are a group of heterogeneous metabolic inherited disorders characterized by the accumulation of organic acids in body fluids and tissues. These are rare disorders and infrequently reported worldwide. In Syria, there is a lack of information regarding these disorders. Objective: Our hospital-based study aimed to describe the pattern of clinical and demographic presenting features of organic acidemias among Syrian children and to shed light on the diagnostic experience of organic acidemias in the Children's Hospital of Damascus through a five year period. Material and methods: We conducted a retrospective cohort study by reviewing the medical records of OA patients in the Children's Hospital of Damascus between 2008 and 2012. All cases were investigated by metabolic work up, including the acylcarnitine profile performed by tandem mass spectrometry (MS/MS) and quantitative urine organic acid analysis performed by gas chromatography mass spectrometry (GC-MS). Results: A total of 70 OA confirmed cases were included in the study. There were 46 males and 31 females. Twenty-seven cases were diagnosed after the first year of life. Methylmalonic acidemia was the most frequent disorder (57.1%). There were relatively high rates of family history of unexplained death and OA confirmed cases (50%), consanguinity (74.2%) and mortality (21.4%). The most frequent symptoms were apnea or respiratory distress (65.7%) and vomiting (40%). Conclusion: The lack of specific confirmatory diagnostic tests being performed and the high mortality and consanguinity rates among OA patients suggests high incidence of OA in Syria. Further studies are needed to determine the actual incidence of OA and the cost-effectiveness of applying a governmental mandatory newborn screening program.

Female and male human babies have distinct blood metabolomic patterns

A sex-gender approach in laboratory medicine is scarce; furthermore, the influence of sex on acylcarnitines and amino acid levels at birth has not been thoroughly investigated, even if sex impacts on newborn screening. We aimed to establish the influence of sex on amino acids and acylcarnitines levels in male and female newborns. Amino acids and acylcarnitines were analysed in dried blood spots using tandem mass spectrometry in male and female newborns. Data were analysed before and after body weight correction also using principal components analysis. This retrospective analytical study showed that females had small but significantly higher levels of amino acids and the correction for body weight amplified these differences. Acylcarnitines were overall higher in males before body weight correction with the exception of isovalerylcarnitine + methylbutyrylcarnitine (C5), which was significantly higher in females. Body weight correction decreased the sex differences in C5. Principal component analysis showed that both amino acids and acylcarnitines were necessary to describe the model for females, whereas only acylcarnitines were required for males. These metabolomics data underline the importance of including sex as a variable in future investigations of circulating metabolites; the existence of sex differences highlights the need for setting distinct reference values for female and male neonates in metabolite concentration.

Propionic acidemia in the Arab World

The autosomal recessive disease propionic acidemia (PA) is an inborn error of metabolism with highly variable clinical manifestations, caused by a deficiency of propionyl-CoA carboxylase (PCC) enzyme, due to mutations in either PCCA or PCCB genes, which encode the alpha and beta subunits of the PCC enzyme, respectively. The classical clinical presentation consists of poor feeding, vomiting, metabolic acidosis, hyperammonemia, lethargy, neurological problems, and developmental delay. PA seems to be a prevalent disease in the Arab World. Arab patients with PA seem to have the same classical clinical picture for PA with distinctive associated complications and other diseases. Most of the mutations found in Arab patients seem to be specific to the Arab population, and not observed in other ethnic groups. In this review, I will discuss in details the clinical and molecular profile of Arab patients with PA.

Methylmalonic acidemia mimicking diabetic ketoacidosis and septic shock in infants

Methylmalonic acidemia (MMA) is most common inherited type of organic acidemia. It has diverse presentation in older infants without any initial apparent symptoms. MMA sometimes present with sudden metabolic decompensation, which may mimics common emergencies like septic shock and diabetic ketoacidosis (DKA) without early recognition can be fatal. In born error of metabolism especially organic acidemia should be suspected in any infant presented with severe high anion gap metabolic acidosis. We report two cases of MMA in infants presented acutely mimicking DKA and septic shock.

A review of the diverse genetic disorders in the Lebanese population: highlighting the urgency for community genetic services

The review lists the genetic diseases reported in Lebanese individuals, surveys genetic programs and services, and highlights the absence of basic genetic health services at the individual and community level. The incidence of individual diseases is not determined, yet the variety of genetic diseases reported is tremendous, most of which follow autosomal recessive inheritance reflecting the social norms in the population, including high rates of consanguinity, which favor the increase in incidence of these diseases. Genetic services including all activities for the diagnosis, care, and prevention of genetic diseases at community level are extremely inadequate. Services are limited to some clinical and laboratory diagnostic services with no genetic counseling. These services are localized within the capital thus preventing their accessibility to high-risk communities. Screening programs, which are at the core of public health prevention services, are minimal and not nationally mandated. The absence of adequate genetic services is attributed to many factors undermining the importance of genetic diseases and their burden on society, the most important of which is genetic illiteracy at all levels of the population, including high-risk families, the general public, and most importantly health care providers and public health officials. Thus, a country like Lebanon, where genetic diseases are expected to be highly prevalent, is in utmost need for community genetics services. Strategies need to be developed to familiarize public health officials and medical professionals with medical genetics leading to a public health infrastructure that delivers community genetics services for the prevention and care of genetic disorders at community level.