The authors review current technologies for clinical genetic testing. Moves are being made towards whole-genome and whole-exome sequencing in the clinic, although other technologies will continue to be of value. Genomic technologies are reaching the point of being able to detect genetic variation in patients at high accuracy and reduced cost, offering the promise of fundamentally altering medicine. Still, although scientists and policy advisers grapple with how to interpret and how to handle the onslaught and ambiguity of genome-wide data, established and well-validated molecular technologies continue to have an important role, especially in regions of the world that have more limited access to next-generation sequencing capabilities. Here we review the range of methods currently available in a clinical setting as well as emerging approaches in clinical molecular diagnostics. In parallel, we outline implementation challenges that will be necessary to address to ensure the future of genetic medicine.

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Molecular genetic testing and the future of clinical genomics

Although information about the precise world distribution and frequency of the inherited hemoglobin disorders is still limited, there is no doubt that they are going to pose an increasing burden on global health resources in the future. Their high frequency is a reflection of natural selection combined with a high frequency of consanguineous marriages in many countries, together with an epidemiological transition; whereby, as public health measures improve in the poorer countries of the world, more babies with these disorders are surviving to present for treatment.

World distribution, population genetics, and health burden of the hemoglobinopathies

Recently, we have witnessed the rapid translation into clinical practice of non-invasive prenatal testing for the common aneuploidies, most notably within the United States and China. This represents a lucrative market with testing being driven by companies developing and offering their services. These tests are currently aimed at women with high/medium-risk pregnancies identified by serum screening and/or ultrasound scanning. Uptake has been impressive, albeit limited to the commercial sector. However, non-invasive prenatal diagnosis (NIPD) for single-gene disorders has attracted less interest, no doubt because this represents a much smaller market opportunity and in the majority of cases has to be provided on a bespoke, patient or disease-specific basis. The methods and workflows are labour-intensive and not readily scalable. Nonetheless, there exists a significant need for NIPD of single-gene disorders, and the continuing advances in technology and data analysis should facilitate the expansion of the NIPD test repertoire. Here, we review the progress that has been made to date, the different methods and platform technologies, the technical challenges, and assess how new developments may be applied to extend testing to a wider range of genetic disorders. © 2013 John Wiley & Sons, Ltd.

https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1002/pd.4124

The clinical implementation of non-invasive prenatal diagnosis for single-gene disorders: challenges and progress made

Krüppeling erythropoiesis: An unexpected broad spectrum of human red blood cell disorders due to KLF1 variants

At present, thalassemia diseases are classified into transfusion-dependent thalassemia and non-transfusion-dependent thalassemia. This classification is based on the clinical severity of patients determining whether they do require regular blood transfusions to survive (transfusion-dependent thalassemia) or not (non-transfusion-dependent thalassemia). In addition to the previous terminology of "thalassemia major" or "thalassemia intermedia," this classification has embraced all other forms of thalassemia syndromes such as α-thalassemia, hemoglobin E/β-thalassemia and combined α- and β-thalassemias. Definitive diagnosis of thalassemia and hemoglobinopathies requires a comprehensive workup from complete blood count, hemoglobin analysis, and molecular studies to identify mutations of globin genes.

Clinical Classification, Screening and Diagnosis for Thalassemia.

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The association of growth differentiation factor-15 levels and osteoporosis in patients with thalassemia.

Haplotype associated with the -31 (A-G) β+ -thalassemia gene in seven Thai individuals were examined and compared with that described originally in Japanese. Seven polymorphic restriction sites wit...

Two Independent Genetic Origins of β+- Thalassemia Due to -31 A to G Mutation in Thai and Japanese Populations

Anemia is one of the major public health problems in in developing countries. It is believed that the main cause is iron deficiency due to the poor iron intake. Previous studies on the burden of anemia focus mainly in pregnant women and pre-school age children. For female university students who have regular blood loss via menstruation, information about the anemia burden and related factors is limited. In this study, we determined the prevalence of anemia, iron deficiency (ID) and iron deficiency anemia (IDA) among 307 female university students in Khon Kaen province. Related factors including social factors, frequency of meat consumption and amount of blood loss via menstruation were collected by using questionnaires. To diagnose anemia, ID and IDA, blood samples were taken to determine hemoglobin concentration and serum ferritin (SF) level. Genetic factors related to anemia (thalassemia) were determined using a combined test approach; i.e. the mean corpuscular volume (MCV) in combination with the DCIP test. Based on Hb < 12 g/dl, anemia prevalence was 36.8% (95% CI =31.4-42.5). Using SF < 15 ng/ml as cutoff value, 25.4% (95% CI =20.6-30.7) had ID. The prevalence of IDA was 14.7 % (95% CI =10.9-19.1).  Analyzing the risk factors for anemia revealed that factors associated with anemia significantly were ID and thalassemia screening (OR = 3.2, 95% CI = 1.9-5.5 and 6.1, 95% CI = 3.6-10.2). Meat consumption did not show any association to anemia, ID and IDA. However, the menstruation period was associated with ID and IDA significantly. Female students who had menstruation period longer than 5 days were 2 times likely to have ID and IDA (OR = 2.0, 95% CI =1.2-3.5 and 2.1, 95% CI =1.1-4.1), as compared to those who had menstruation within 3-5 days. These findings indicate that ID and IDA among female university students may result from blood loss via menstruation rather than a low intake of meat.

Anemia, iron deficiency and iron deficiency anemia among female university students in Khon Kaen Province: relationship to menstruation

Hemoglobin Constant Spring (Hb CS) and Hb Pakse' (PS) are the common non-deletional α+-thalassemia found in Thailand. These two variants can cause severe thalassemia syndromes, especially in fetus ...

Direct PCR assays without DNA extraction for rapid detection of hemoglobin Constant Spring and Pakse' genes: application for carrier screening and prenatal diagnosis.

Supawadee Yamsri

Papers

The association of growth differentiation factor-15 levels and osteoporosis in patients with thalassemia.

Two Independent Genetic Origins of β+- Thalassemia Due to -31 A to G Mutation in Thai and Japanese Populations

Anemia, iron deficiency and iron deficiency anemia among female university students in Khon Kaen Province: relationship to menstruation

Direct PCR assays without DNA extraction for rapid detection of hemoglobin Constant Spring and Pakse' genes: application for carrier screening and prenatal diagnosis.

JAK2V617F mutation in patients with β-thalassemia disease: prevalence and clinical characteristics