Dietary management of inborn errors of metabolism

Recurrent dislocation of binocular crystal lenses in a patient with cystathionine beta-synthase deficiency

Background

Ectopia lentis is the common ocular manifestation of homocystinuria resulting from cystathionine beta-synthase (CBS) deficiency which has a high risk of thromboembolic complications.

Case presentation

The present study reports the case of a teenager with recurrent lens dislocation and glaucoma. He was diagnosed with CBS deficiency according to a high level of serum homocysteine and compound heterozygous mutations at two different positions on the CBS gene. Antiglaucoma eyedrops and a mydriatic successfully controlled the intraocular pressure, while oral pyridoxine and betaine uptake lowered the serum homocysteine level effectively.

Conclusions

Children with CBS deficiency may suffer from ectopia lentis, glaucoma and/or amblyopia. We firstly discovered a new mutation of CBS c. 697 T > G which had not been reported before. The patient was pyridoxine responsive and well controlled by medicine.

Holistic Approach in the Management of Skeletal Deformity in a Case of Homocystinuria

INTRODUCTION

Homocystinuria has a wide range of clinical presentations ranging from near normal intelligence and appearance with just lens dislocation and minimal skeletal deformities to severe mental retardation with gross skeletal deformities. In this background, we describe one such case with skeletal deformity managed comprehensively.

CASE REPORT

A 17-year-old boy presented with complaints of deformity of the left lower limb since childhood more evident for the past 5 years along with a history of blurring of vision. On examination the pubis-heal length > crown-pubis length along with genu valgum of left lower-limb with 16 cm intermalleolar distance. He also had a superolateral subluxation of the lens in both eyes. Valgus angle was 16° on the left leg compared to 6° on the right. The diagnosis of homocystinuria was confirmed by biochemical investigations. The left side genu valgum was addressed with medial closing wedge osteotomy and fixed with distal femur locking compression plating. Lens subluxation was treated with posterior chamber intra-ocular lens surgery. He was also given medical treatment and on regular monitoring of his homocysteine levels. The patient had good functional outcome at 2-year follow-up.

CONCLUSION

Homocystinuria is a rare disease that needs early identification and effective management to avoid complications. Skeletal complications are common and include genu valgum, pes cavus, chest wall deformities, and skeletal deformities such as kyphosis and scoliosis. Skeletal deformities can be avoided when identified early and associated osteoporosis which is managed effectively. A holistic approach is needed in the management of such patients with inter-departmental coordination to bring quality to the life of patients with homocystinuria.

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.

Genomics of rare genetic diseases-experiences from India

Home to a culturally heterogeneous population, India is also a melting pot of genetic diversity. The population architecture characterized by multiple endogamous groups with specific marriage patterns, including the widely prevalent practice of consanguinity, not only makes the Indian population distinct from rest of the world but also provides a unique advantage and niche to understand genetic diseases. Centuries of genetic isolation of population groups have amplified the founder effects, contributing to high prevalence of recessive alleles, which translates into genetic diseases, including rare genetic diseases in India.Rare genetic diseases are becoming a public health concern in India because a large population size of close to a billion people would essentially translate to a huge disease burden for even the rarest of the rare diseases. Genomics-based approaches have been demonstrated to accelerate the diagnosis of rare genetic diseases and reduce the socio-economic burden. The Genomics for Understanding Rare Diseases: India Alliance Network (GUaRDIAN) stands for providing genomic solutions for rare diseases in India. The consortium aims to establish a unique collaborative framework in health care planning, implementation, and delivery in the specific area of rare genetic diseases. It is a nation-wide collaborative research initiative catering to rare diseases across multiple cohorts, with over 240 clinician/scientist collaborators across 70 major medical/research centers. Within the GUaRDIAN framework, clinicians refer rare disease patients, generate whole genome or exome datasets followed by computational analysis of the data for identifying the causal pathogenic variations. The outcomes of GUaRDIAN are being translated as community services through a suitable platform providing low-cost diagnostic assays in India. In addition to GUaRDIAN, several genomic investigations for diseased and healthy population are being undertaken in the country to solve the rare disease dilemma.In summary, rare diseases contribute to a significant disease burden in India. Genomics-based solutions can enable accelerated diagnosis and management of rare diseases. We discuss how a collaborative research initiative such as GUaRDIAN can provide a nation-wide framework to cater to the rare disease community of India.

Imaging in Pediatric Extra-Pulmonary Tuberculosis

Extrapulmonary tuberculosis in children tends to be more severe than the adults. It can affect almost any organ system of the body. The clinical manifestations are often non-specific. Imaging findings are also not always very specific. This article describes the imaging spectrum of pediatric extrapulmonary tuberculosis.

Guidelines for the diagnosis and management of cystathionine beta-synthase deficiency

Cystathionine beta-synthase (CBS) deficiency is a rare inherited disorder in the methionine catabolic pathway, in which the impaired synthesis of cystathionine leads to accumulation of homocysteine. Patients can present to many different specialists and diagnosis is often delayed. Severely affected patients usually present in childhood with ectopia lentis, learning difficulties and skeletal abnormalities. These patients generally require treatment with a low-methionine diet and/or betaine. In contrast, mildly affected patients are likely to present as adults with thromboembolism and to respond to treatment with pyridoxine. In this article, we present recommendations for the diagnosis and management of CBS deficiency, based on a systematic review of the literature. Unfortunately, the quality of the evidence is poor, as it often is for rare diseases. We strongly recommend measuring the plasma total homocysteine concentrations in any patient whose clinical features suggest the diagnosis. Our recommendations may help to standardise testing for pyridoxine responsiveness. Current evidence suggests that patients are unlikely to develop complications if the plasma total homocysteine concentration is maintained below 120 μmol/L. Nevertheless, we recommend keeping the concentration below 100 μmol/L because levels fluctuate and the complications associated with high levels are so serious.

Gas chromatography/mass spectrometry-based urine metabolome study in children for inborn errors of metabolism: An Indian experience

OBJECTIVE

The present study highlights the feasibility of gas chromatography/mass spectrometry (GC/MS)-based analysis for simultaneous detection of >200 marker metabolites in urine found in characteristic pattern in inborn errors of metabolism (IEM) in India.

DESIGN AND METHODS

During this retrospective study conducted from July 2013 to January 2016, we collected urine specimens on filter papers from Indian children across the country along with relevant demographic and clinical data. The laboratory technique involved urease pretreatment followed by deproteinization, derivatization, and subsequent computer-aided analysis of organic acids, amino acids, fatty acids, and sugars by GC/MS, which enable chemical diagnosis of IEM.

RESULTS

Totally 23,140 patients were investigated for IEM with an estimated frequency of about 1.40%, that is, 323 positive cases. Most frequent disorders observed were of primary lactic acidemia (27.2%) and organic acidemia (methylmalonic aciduria, glutaric acidemia type I, propionic aciduria, etc.) followed by aminoacidopathies (maple syrup urine disease, phenylketonuria, tyrosinemia, etc.). Furthermore, alkaptonuria, canavan disease, and 4-hydroxybutyric aciduria were also diagnosed. Prompt treatment following diagnosis led to a better outcome in a considerable number of patients.

CONCLUSIONS

GC/MS with one-step metabolomics enables quick detection, accurate identification, and precise quantification of a wide range of urinary markers that may not be discovered using existing newborn screening programs. The technique is effective as a second-tier test to other established screening technologies, as well as one-step primary screening tool for a wide spectrum of IEM.

50 years of tuberculosis control in India: progress, pitfalls and the way forward

India established the National Tuberculosis Control Project (NTCP) 50 years ago and re-designed it as Revised NTCP (RNTCP) 19 years ago. Tuberculosis (TB) control was beset with obstacles-BCG vaccination was found ineffective in TB control in 1979; human immunodeficiency virus began spreading in India since 1984 with TB as the commonest opportunistic disease; multi-drug resistance was found to be prevalent since 1992. The World Health Organization declared TB as global emergency in 1993. Yet, RNTCP was extended to the whole nation very slowly, taking 13 years from inception. The first objective of RNTCP, namely 85% treatment success has been achieved and case-fatality had dropped by 90%;. Still, TB burden continues to remain huge; about half the cases are not getting registered under RNTCP; pediatric TB is neglected; TB drains national economy of US$ 23 billion annually. Therefore, TB control is in urgent need of re-design and re-invigoration, with additional inputs and system re-organization to cover all such gaps. We highlight the need for Public Health infrastructure under which all vertical disease control projects such as RNTCP should be synergized for better efficiency and for establishing Public Health Surveillance for collecting denominator-based data on incidence and prevalence to guide course corrections. India ought to spend 3 to 5 times more on TB control than at present. Control needs clear epidemiologic definition and measurable parameters for monitoring the level of control over time. TB control is both a measure of, and a means to, socioeconomic development.

Long-chain polyunsaturated fatty acids in inborn errors of metabolism

The treatment of children with inborn errors of metabolism (IEM) is mainly based on restricted dietary intake of protein-containing foods. However, dietary protein restriction may not only reduce amino acid intake, but may be associated with low intake of polyunsaturated fatty acids as well. This review focuses on the consequences of dietary restriction in IEM on the bioavailability of long-chain polyunsaturated fatty acids (LCPUFAs) and on the attempts to ameliorate these consequences. We were able to identify during a literature search 10 observational studies investigating LCPUFA status in patients with IEM and six randomized controlled trials (RCTs) reporting effect of LCPUFA supplementation to the diet of children with IEM. Decreased LCPUFA status, in particular decreased docosahexaenoic acid (DHA) status, has been found in patients suffering from IEM based on the evidence of observational studies. LCPUFA supplementation effectively improves DHA status without detectable adverse reactions. Further research should focus on functional outcomes of LCPUFA supplementation in children with IEM.

Approach to inborn errors of metabolism presenting in the neonate

Inborn errors of metabolism (IEM) are an important cause of acute illness in newborns. Presentation may mimic common neonatal conditions such as sepsis. Prompt detection requires a high index of suspicion and the early measurement of biochemical markers such as blood ammonia. Diagnosis is important not only for treatment but also for genetic counselling. Guidelines for diagnosis and early management of IEM presenting in the neonatal period are described.

Refractory seizures associated with an organic aciduria in a dog

A 6-month-old, female Cavalier King Charles spaniel exhibited seizures that were difficult to control with standard anticonvulsants over a 12-month period. The diagnosis of an organic aciduria with excessive excretion of hexanoylglycine was determined when the dog was 20 months old. Recurrent and cluster seizures were eventually controlled with the addition of levetiracetam to potassium bromide and phenobarbital.