Spinal Muscular Atrophy: History, Current Status and Future / 罕见病研究

It has been a hundred years since the first case of spinal muscular atrophy(SMA) was reported in the medical literature. In its 100 years of history, medical development for the cure of SMA has gone through many stages, from clinical manifestation description, accumulation of cases, disease classification exploration to pathogenic gene mapping and cloning, clinical application of gene diagnosis, animal model establishment then to R&D of disease modifying drugs and clinical use of novel therapies. The future of the development lies in breakthrough in pathophysiological mechanism, carrier screening and precise prevention, as well as new therapies. As a representative of monogenic rare diseases, review the history of the progress in diagnosis and treatment and R&D in medications and discuss the prospect of further development in the future is instrumental in leading the continued advancement of the whole cause of rare disease.

Genetic counseling to a DMD asymptomatic carrier: First case report in the Peruvian public healthcare system / Asesoramiento genético a una portadora asintomática de DMD: Primer caso reportado en el Sistema de Salud Pública del Perú

SUMMARY Duchenne muscular dystrophy (DMD) is a rapidly progressive dystrophinopathy with X-linked inheritance. This report describes a woman with a family history of male relatives affected by DMD, as she sought out genetic counseling about her concerns related to family planning and risks of eventually having children with the disease. We proposed her to get involved in a pilot program for carrier-status diagnosis and genetic counseling. This case illustrates the importance of a genetic counseling program for diagnosis of asymptomatic carriers in neurogenetic diseases, particularly in regions with low-resource settings. We discussed successes and misunderstandings faced throughout the process, supporting policies for present and future challenges from this and similar kinds of diagnoses.

RESUMEN La distrofia muscular de Duchenne (DMD) es una distrofinopatía rápidamente progresiva con herencia ligada al cromosoma X. Este reporte describe el caso de una mujer con historia familiar de hermano y sobrinos con DMD, que acudió a consulta para orientación e información sobre riesgos inherentes a una eventual planificación familiar. Le propusimos participar en un programa piloto de asesoramiento genético para determinar su estado de portador o no de la variante causal de DMD en la familia. Esta primera experiencia ilustra la importancia de tener un programa de asesoramiento genético para el diagnóstico de portadores asintomáticos de enfermedades neurogenéticas en regiones con bajos recursos. Se incluyen reflexiones y comentarios sobre aspectos positivos y retos presentados durante el proceso, las políticas de apoyo presente y futuro para el afronte de los complejos problemas planteados por éste y similares diagnósticos.

Costo-efectividad de la prueba de secuenciación del gen CFTR para portadores asintomáticos en la población colombiana / Cost-effectiveness of the CFTR gene-sequencing test for asymptomatic carriers in the Colombian population

Introducción. La fibrosis quística es una enfermedad genética de carácter autosómico recesivo clasificada como enfermedad huérfana de alto costo. Objetivo. Determinar la razón de costo-efectividad de la prueba diagnóstica de secuenciación del gen CFTR para los portadores asintomáticos familiares en primer, segundo y tercer grados de consanguinidad. Materiales y métodos. Se hizo una búsqueda sistemática sobre la evaluación de las características operativas de la prueba diagnóstica y los modelos de árbol de decisiones en estudios de costo-efectividad. Se elaboró un modelo de árbol de decisiones tomando como unidad de análisis la prevención de futuras concepciones. Los costos de la enfermedad se obtuvieron del reporte de alto costo del Ministerio de Salud de Colombia. Los costos de la prueba se obtuvieron de laboratorios nacionales. Se hizo un análisis de sensibilidad, determinístico y probabilístico, con la perspectiva del tercer pagador y horizonte a un año. Resultados. Se obtuvo una razón incremental de costo-efectividad (RICE) de USD$ 5.051,10 por obtener 10,89 % más de probabilidades de evitar el nacimiento de un niño enfermo con fibrosis quística por pareja. Para los familiares de segundo y tercer grados, se encontró una RICE de USD$ 19.380,94 y USD$ 55.913,53, respectivamente, al aplicar el PIB per cápita. Esta tecnología fue costo-efectiva en 39 %, 61,18 % y 74,36 % para 1, 2 y 3 PIB per cápita en familiares de primer grado de consanguinidad. Conclusiones. La prueba genética de detección de portadores del gen CFTR resultó costo-efectiva dependiendo del umbral de la disponibilidad de pagar, y de los supuestos y limitaciones establecidas en el modelo.

Introduction: Cystic fibrosis is an autosomal recessive genetic disease classified as a high- cost orphan disease. Objective: To determine the cost-effectiveness ratio of the diagnostic test for the CFTR gene-sequencing in asymptomatic family carriers in the first, second, and third degree of consanguinity. Materials and methods: We conducted a systematic search evaluating operative characteristics of the diagnostic test and decision-tree models in cost-effectiveness studies. A decision-tree model was elaborated taking prevention of future conceptions as a unit of analysis. We obtained the costs of the disease from the high-cost report of the Ministerio de Salud y Protección Social. The costs of the test were referenced by national laboratories. We carried out a deterministic and probabilistic sensitivity analysis with a third-payer perspective and a one-year horizon. Results: An ICER of USD$ 5051.10 was obtained as the incremental cost for obtaining 10.89% more probability of avoiding the birth of a child with cystic fibrosis per screened couple. For family members in second and third degrees, the ICER was USD$ 19,380.94 and USD$ 55,913.53, respectively, evidenced when applying the GDP per capita. This technology was cost-effective in 39%, 61.18%, and 74.36% for 1, 2, and 3 GDP per capita in first degree of consanguinity relatives. Conclusions: The genetic test for the detection of CFTR gene carriers was cost-effective depending on the threshold of availability to pay and the assumptions and limitations established in the model.

Experience with NESTROFT for screening for thalassemia trait/ minor: evaluation against CBC and HPLC in a high prevalence region in Saurashtra, Gujarat, India

Background: Hemoglobinopathies pose a significant health burden in India. Prevention programmes can significantly reduce this burden. Although sophisticated methods of screening for β thalassemia trait are available, a cheap and simple method is beneficial for population screening. Although the Naked Eye Single Tube Red Cell Osmotic Fragility Test (NESTROFT) has been evaluated in many studies, sample sizes were small in some and many earlier studies have not done complete blood count (CBC) and High-Performance Liquid Chromatography (HPLC) in all the cases. We evaluate the suitability of NESTROFT for detection of β-thalassemia trait in a high prevalence region in Saurashtra, Gujarat.Methods: Here, 1000 unrelated individuals were studied. NESTROFT, CBC and estimation of HbA2 and HbF or other hemoglobin variants were done by HPLC.Results: Prevalence of β thalassemia trait was 7.8% in this population. NESTROFT showed an overall sensitivity and specificity of 94.87 and 85.38 respectively for the detection of β thalassaemia trait. Using red cell indices (MCH <27 pg and MCV <80 fl), One β thalassemia trait with normal indices would have been missed. Among twelve individuals with other hemoglobinopathies (HbS, HbD, HbE, δβ thalassemia trait or HPFH), seven had a positive NESTROFT while three had normal MCV & MCH values.Conclusions: NESTROFT is a cost-effective sensitive test which does not require any equipment and can be done in remote areas. It remains a useful first line screening test when large populations have to be screened.

Reproductive intervention for inborn errors of metabolism / 中华实用儿科临床杂志

Inborn errors of metabolism(IEM)are a large class of genetic diseases caused by congenital metabolic disturbance.IEM results in complex clinical phenotype and it is an important cause of disability,death,and stupidity for the children.The technique of reproductive intervention including prenatal diagnosis(PND)or preimplantation genetic diagnosis(PGD)is an important approach to avoid the birth of defect.According to the two basic characteristics of IEM,metabolic disturbance and gene mutation,the clinical application of PND/PGD technology in IEM are reviewed,and put forward a new idea for reproductive intervention based on carrier screening.

Screening for thalassemia and other hemoglobinopathies in a tertiary care hospital of West Bengal: Implications for population screening.

Hemoglobinopathies are common genetic disorders of hemoglobin, which can be prevented by population screening and offering genetic counseling. In absence of population-based screening for hemoglobinopathies, the hospital-based diagnosis register provide idea about the extent of problem in the community. The present study was undertaken to find out the burden of hemoglobinopathies and spectrum of this disorders among the population who were screened in the hospital-based screening program. A record-basedanalysis of subjects who underwent screening for hemoglobinopathies in Burdwan Medical College and Hospital over a period of 3 years and 4 months revealed that overall 29.3% of subjects were positive for hemoglobinopathies. Beta thalassemia heterozygous was the most commonhemoglobinopathy in this region closely followed by hemoglobin E heterozygous. In view of high prevalence of hemoglobinopathies in this region, a routine premarital screening program is needed for identification and prevention of high-risk marriages.

Distribution of alpha thalassaemia in 16 year old Malaysian Students in Penang, Melaka and Sabah

Objectives: Alpha thalassaemia is wide spread in Malaysia and is a public health problem. This study aimed to describe the carrier frequencies of α‒thalassaemia and its distribution among major ethnic groups in three states of Malaysia. Methods: Educational forums were organised and study was explained to students from three schools. Students were invited to take part in the screening with parent consent. A total of 8420 adolescent students aged 16 years volunteered to participate in the study. Peripheral blood samples were analysed for complete blood counts, haemoglobin quantification and typing, and serum ferritin levels. Genomic DNA was used for screening alpha thalassaemia alleles by PCR based molecular methods. Results: We identified seven α‒globin gene defects in 341 (4.08%) students: amongst them α+‒ and α0‒thalassaemias were detected in 232 (2.77%) and 107 (1.28%) students respectively. Genotype ‒α3.7/αα was the most prevalent among sub-populations of Malay, indigenous communities of Sahab and Indian, while ‒‒SEA/αα deletion is more prevalent in Malaysian Chinese. It is estimated that 63 pregnancies annually are at risk of Hb Bart’s hydrops fetalis. Conclusions: We have demonstrated the prevalence and mutation patterns of α‒thalassaemia in the 16 year olds in three states of Malaysia. High α0‒thalassaemia deletions amongst the study subjects place these carriers at an increased risk of conceiving fetuses with HbH disease and Hb Bart’s hydrops fetalis should they choose another heterozygous partner. It is therefore highly recommended to institute community screening programmes and provide prospective carriers with genetic counselling to help them make informed choices.

Past, present & future scenario of thalassaemic care & control in India.

The first case of thalassaemia, described in a non-Mediterranean person, was from India. Subsequently, cases of thalassaemia were documented in all parts of India. Centres for care of thalassaemics were started in the mid-1970s in Mumbai and Delhi, and then in other cities. The parent's associations, with the help of International Thalassemia Federation, greatly helped in improving the care of thalassaemics. Obtaining blood for transfusion was difficult, but the Indian Red Cross Society and the parent's associations played a crucial role in arranging voluntary donations of blood. Chelation with deferoxamine was used sparingly due to the high cost. The Indian physicians conducted trials with deferiprone, and the drug was first approved and marketed in India. Deferasirox is also now being administered. Studies of physical and pubertal growth documented significant retardation, suggesting that generally patients receive inadequate chelation and transfusions. Bone marrow transplantation is available at a number of centres, and cord blood stem cell storage facilities have been established. Information about mutations in different parts of India is available, and ThalInd, an Indian database has been set up. There is a need to set up preimplantation genetic diagnosis and non-invasive prenatal diagnosis. It is argued that too much emphasis should not be placed on premarital screening. The focus should be on screening pregnant women to yield immediate results in reducing the burden of this disorder. Care of thalassaemia has been included in the 12th 5-year Plan of the Government of India. Many States now provide blood transfusions and chelation free of cost. Although inadequacies in care of thalassaemia remain, but the outlook is bright, and the stage is set for initiating a control programme in the high risk States.