Frequency of Inborn Errors of Metabolism in a Northeastern Iranian Sample with High Consanguinity Rates

Expanded inherited metabolic diseases screening by tandem mass spectrophotometry: The first report from Iran

Inherited metabolic diseases (IMD) are a group of rare genetic disorders that can present with a variety of symptoms. Since these disorders are hard to treat once the symptoms occur, neonatal screening may be a logical strategy. Here we evaluate the first results of national expanded IMD screening in Iran. A total of 46 IMDs were screened in this national program. Between April 2018 and March 2022, all infants who underwent national IMD screening at Shahid Beheshti University of Medical Sciences were included in this study. History and Physical examinations of infants, screening results, recall rate, response rate, and prevalence of IMDs were evaluated. A total of 125,819 infants were screened during this period. The recall rate of the test was 0.81%. 124 cases were diagnosed with a definite IMD and the raw overall prevalence of IMDs was estimated to be 1:1015. Aminoacidopathies were the most commonly detected disorders and Hyperphenylalaninemia/PKU was the most prevalent disorder among all groups. Since IMDs vary from region even in a single country, screening for IMDs is crucial in societies with a high rate of consanguineous marriages. More studies are essential for figuring out the most efficient combination of diseases to be screened based on countries' facilities.

Newborn screening for isovaleric acidemia: A case report of a Chinese patient with novel variants

Isovaleric acidemia (IVA) is a rare autosomal recessive disorder that manifests as a deficiency of isovaleryl-CoA dehydrogenase (IVD), a key enzyme in leucine metabolism. The clinical presentations associated with IVD deficiency are variable and include feeding intolerance, vomiting, metabolic acidosis, ketonemia, "sweaty feet" odor, lethargy, coma and even death. Tandem mass spectrometry (MS/MS) and gas chromatography-mass spectrometry (GC/MS) methods were used to perform organic acid analysis of blood and urine samples from IVA patients, and the genetic analysis included next generation sequencing (NGS) and Sanger sequencing of the IVD gene. Here, we report the case of an almost seven-year-old male patient from a Chinese family who was asymptomatic during the newborn period, including the clinical manifestations and examination results. Genetic analysis revealed a previously unreported compound heterozygous variant in the IVD gene: c.593G > C (p.W198S) and c.859C > T (p.R287W).

Determination of Normal Range of Acylcarnitine in Neonatal Dried Blood Spots using LC-MS/MS

Background

Acylcarnitine is one of the crucial markers of fatty acid metabolism, and examination of their level in infants can reveal several Inherited Metabolic Disorders (IDM) or Inborn errors of Metabolism (IEM). Because of the great importance of hereditary, metabolic, and other inherited disorders early diagnosis before the appearance of clinical symptoms, this study was carried out to establish a reference range for carnitine analytes and to identify acylcarnitine profiles in normal weight neonatal dried blood spots (DBS) specimens.

Methods

By using liquid chromatography tandem mass spectrometry (LC-MS/MS) for neonatal screening and eventually the examination and analysis of LC-MS/MS results, 34 acylcarnitine derivatives were identified.

Results

The normal range for acylcarnitine analytes with carbon numbers ranging from zero to 18, both main and the branched ones, were ultimately measured. Afterward, they were compared with the results of some other diagnostic laboratories to be verified.

Conclusions

This study differed from the other findings, which could be due to diversity in population and work methods. However, the reference range of most acylcarnitine derivatives in Tehran closely aligned with this study's findings.

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.

Incidence of Inborn Errors of Metabolism in Newborn Infants: Five Years' Single-Center Experience, Jeddah, Saudi Arabia

Inborn errors of metabolism (IEMs) are inherited biochemical/metabolic disorders that are commonly present in the immediate neonatal period. The aim of this retrospective study was to determine the incidence and distribution of IEMs in newborn infants delivered in our hospital and to evaluate its outcome. A total of 16 494 (99.9%) newborn infants were screened for IEMs. We found 29 newborn infants diagnosed with IEMs, representing an incidence of 1 per ~569 live births and a cumulative incidence of 176 per 100 000 live births of the IEM-positive newborn infants. We detected 11 different types of IEMs, and the top 6 categories were endocrinopathies followed by carbohydrates disorders, vitamin-responsive disorders, organic acid defects, and ketogenesis and ketolysis defects. This study does reflect upon the importance of educating the general population about the perils of Consanguineous Marriages (CMs) in order to reduce related disorders significantly, especially in families who have a history of IEMs.

Assessment of Perceptions and Predictors Towards Consanguinity: A Cross-Sectional Study from Palestine

Background/Aim

Consanguinity represents a biological relationship between two individuals. In clinical genetics, it specifically refers to the marriage between individuals who are second cousins or closer. The aim of the study is to assess perceptions and their predictors among the Palestinian population towards consanguinity.

Methods

A survey-based cross-sectional study was conducted. The sample was collected using convenience and snowball sampling methods, yielding a sample of 1008 participants. The perceptions towards consanguinity and its predictors were assessed using Chi-square test.

Results

The prevalence of consanguinity among married participants was 18.7% (N = 81/432), while it was 28.8% among their parents. Consanguinity rate was significantly low among the young age group (ie, <47 years old) and among participants whose mothers have undergraduate educational levels (P < 0.05). Other factors like parental consanguinity, educational level of participants, their father's educational level, and residency place showed no significant associations (P > 0.05). Rejection of consanguinity was significantly noted among young age participants, absence of parental consanguinity, the presence of children or family members with genetic disorders and female gender (P < 0.001). Furthermore, participants who indicated that they are governmental employees, those with 2000-5000 ILS monthly income, those who are married (P < 0.01), and those who indicated that their mothers are holders of postgraduate degree were significantly more likely to reject the idea of consanguinity (P < 0.05). Also, medical and/or scientific reasons were significantly associated with rejecting the idea of consanguinity (P < 0.001).

Conclusion

Consanguinity prevalence has decreased among recent generations in Palestine, but it remains a significant challenge in Palestine. Therefore, educational and awareness programs about consanguinity and its health effects are effective strategies for reducing the consanguinity rate, especially for persons who are at the age of marriage.

Frequency of carriers for rare metabolic diseases in a Brazilian cohort of 320 patients

BACKGROUND

Several metabolic disorders follow an autosomal recessive inheritance pattern. Epidemiological information on these disorders is usually limited in developing countries. Our objective is to assess carrier frequencies of rare autosomal recessive metabolic diseases in a cohort of Brazilian patients that underwent molecular investigation with exome sequencing and estimate the overall frequency of these diseases using the Hardy-Weinberg equation.

METHODS AND RESULTS

We reviewed the molecular findings of 320 symptomatic patients who had carrier status for recessive diseases actively searched. A total of 205 rare variants were reported in 138 different genes associated with metabolic diseases from 156 patients, which represents that almost half (48.8%) of the patients were carriers of at least one heterozygous pathogenic/likely pathogenic (P/LP) variant for rare metabolic disorders. Most of these variants are harbored by genes associated with multisystemic involvement. We estimated the overall frequency for rare recessive metabolic diseases to be 10.96/10,000 people, while the frequency of metabolic diseases potentially identified by newborn screening was estimated to be 2.93/10,000.

CONCLUSIONS

This study shows the potential research utility of exome sequencing to determine carrier status for rare metabolic diseases, which may be a possible strategy to evaluate the clinical and social burden of these conditions at the population level and guide the optimization of health policies and newborn screening programs.

A Great Catch for Investigating Inborn Errors of Metabolism-Insights Obtained from Zebrafish

Inborn errors of metabolism cause abnormal synthesis, recycling, or breakdown of amino acids, neurotransmitters, and other various metabolites. This aberrant homeostasis commonly causes the accumulation of toxic compounds or depletion of vital metabolites, which has detrimental consequences for the patients. Efficient and rapid intervention is often key to survival. Therefore, it requires useful animal models to understand the pathomechanisms and identify promising therapeutic drug targets. Zebrafish are an effective tool to investigate developmental mechanisms and understanding the pathophysiology of disorders. In the past decades, zebrafish have proven their efficiency for studying genetic disorders owing to the high degree of conservation between human and zebrafish genes. Subsequently, several rare inherited metabolic disorders have been successfully investigated in zebrafish revealing underlying mechanisms and identifying novel therapeutic targets, including methylmalonic acidemia, Gaucher’s disease, maple urine disorder, hyperammonemia, TRAPPC11-CDGs, and others. This review summarizes the recent impact zebrafish have made in the field of inborn errors of metabolism.

Plasma amino acid levels in a cohort of patients in Turkey with classical phenylketonuria

Background

In patients with phenylketonuria, the central nervous system is adversely affected by noncompliance with diet. The levels of phenylalanine and many different amino acids (AAs) in the plasma of patients with phenylketonuria can be measured simultaneously.

Objectives

To measure the blood plasma levels of neurotransmitter AAs in a cohort of patients in Sanliurfa province, Turkey, with phenylketonuria for use as a support parameter for the follow-up of patients.

Methods

The phenylketonurics that we followed (n = 100) were divided into 2 groups according to their compliance with their dietary treatment. Plasma AA analysis results of phenylketonurics were compared with those of healthy children in a control group (n = 50).

Results

In the diet incompliant group (n = 56), the mean levels of γ-aminobutyric acid (GABA; 0.96 ± 1.07 μmol/L) and glycine (305.1 ± 105.19 μmol/L) were significantly higher than those in the diet compliant group (n = 44; GABA P = 0.005, glycine P < 0.001) and in the control group (GABA and glycine P < 0.001), whereas the mean levels of glutamic acid (39.01 ± 22.94 μmol/L) and asparagine (39.3 ± 16.89 μmol/L) were lower (P < 0.001) in the diet incompliant group. A positive correlation was observed between the levels of phenylalanine and GABA and glycine. A negative relationship was found between the levels of phenylalanine and glutamic acid and asparagine.

Conclusions

A relationship exists between the levels of plasma phenylalanine in a cohort of phenylketonurics in Sanliurfa province, Turkey, and the levels of some excitatory and inhibitory AAs. Excitatory and inhibitory AA levels in plasma may be used as support parameters in the follow-up of patients with phenylketonuria.

Genetics and genomic medicine in Iran

Attention has been focused on the field of genetics and genomics in Iran in recent years and some efforts have been enforced and implemented. However, they are totally not adequate, considering the advances in medical genetics and genomics in the past two decades around the world. Overall, considering the lack of medical genetics residency programs in the Iranian health education system, big demand due to high consanguinity and intraethnic marriages, there is a lag in genetic services and necessity to an immediate response to fill this big gap in Iran. As clarified in the National constitution fundamental law and re-emphasized in the 6th National Development Plan, the Iranian government authority is in charge of providing the standard level of health including genetic services to all Iranian individuals who are in need.