Abstract
The field of IEI is rapidly evolving after the introduction of next-generation sequencing (NGS) platforms, such as whole exome sequencing (WES) and whole genome sequencing (WGS). In recent years, the application of these tools has significantly increased the identification of genetic defects causing IEI. This expansion has enhanced our understanding of genotype-phenotype correlation and provided valuable pathogenetic and pathophysiological insights into IEI. However, further studies are needed to complete our understanding, especially in specific geographical populations where studies are conducted rarely such as in South-East Asia region. Furthermore, most modern genetic approaches, such as WES and WGS, are not affordable or available to a large portion of the global population, particularly in low-income developing countries. Even simple initial immunological tests such as immunoglobulin measurement, may not be accessible in such countries. Therefore, there is a need to develop or optimize accessible and affordable tests.
Part I of this thesis describes the development of affordable techniques for the diagnosis of IEI. Chapter 2 represents the first study in which WES was applied for genetic testing in the Thai pediatric population suspected of IEI. Importantly, the study revealed novel variants associated with IEIs, which guided to a definite diagnosis and changed the treatment approaches for the tested patients, including the decision to perform the allogeneic stem cell transplantation. The results from this study expand our knowledge of the genotype-phenotype spectrum of IEI.
However, utilizing WES and WGS for genetic analysis in a clinical setting has limitations. These techniques are time-consuming, costly, and involve complex data analysis and interpretation. Due to high costs and limited resources, NGS is not widely available in many developing countries. Therefore, there is a need to explore rapid, robust, and inexpensive molecular tools to address this gap. Chapter 3 describes the development of a rapid, low-cost customized microarray for genetic diagnosis in IEI. This technique demonstrated its promising potential as a first-line screening tool in developing countries. Further, the methods for microarray bioinformatics are reviewed in Chapter 4.
While modern genetic testing methods provides important insights into the pathophysiology of IEI and guides to the therapeutic approach, the analysis starts with simple tests (“basic to the basics”) in order to investigate immunological changes in patients according to their phenotype. International consensus guidelines recommend prompt measurement of serum immunoglobulin (Ig)G in patients suspected of having an antibody deficiency. However, in many developing countries, even such tests are only available in referral centers and not easily accessible to a substantial number of people. Measurement of total serum globulin levels, routinely assessed in liver biochemistry testing, can be an attractive candidate for screening hypogammaglobulinemia in developing countries. Chapter 5 describes the development of a model that predicts immunoglobulin G levels in children using serum globulin levels combined with the patient's disease status. This model facilitates timely decision-making for initiating immunoglobulin therapy in pediatric patients suspected of hypogammaglobulinemia in developing countries.
The presentation of IEI patients can be very diverse with atypical immunological manifestations and non-immunological comorbidities. Part II of the thesis describes different intriguing cases, demonstrating the diverse clinical spectrum of IEI patients. Chapter 6 describes a patient with hypomorphic DOCK8 variants who exhibited a milder phenotype compared to the typical DOCK8-deficient patients. Making a definite diagnosis is a challenge for such a patient. In comparison, DOCK8 deficiency was diagnosed in another more typical patient (chapter 7) who was experiencing recurrent episodes of different types of hematological malignancies, highlighting the role of DOCK8 in immune surveillance of malignancies. Chapter 8 describes the lifelong clinical course of two sisters with identical damaging NBAS variants, who suffered from combined immunodeficiency, autoimmunity, allergy and malignancy. Chapter 9 describes a patient in whom the innate immune system is affected. Genetic analysis revealed damaging FERMT3 variants. The patient was then diagnosed with leukocyte adhesion deficiency (LAD) type III. However, unexpectedly an impairment of the antibody production was found as well in this patient. This was never reported and indicated a defect in the adaptive immune system. Immunoglobulin replacement therapy led to a dramatic clinical improvement in this patient. Chapter 10 provides insights into a patient with congenital glycosylation disorder and a severe immune deficiency. Novel compound heterozygous variants in PGM3 were found. The longstanding history of this patient with immunodeficiency as well as the recovery time of PGM3 activity after a matched related donor stem cell transplantation is discussed.
Traditionally, allergy has been regarded as a polygenic disease, influenced by genetic susceptibility in the form of single nucleotide polymorphisms (SNPs) that interact with immunomodulating factors in the environment. However, allergy has been recognized as a frequent immunological comorbidity in IEIs. Recently, a new subcategory of IEIs known as "primary atopic disorders" has been proposed, mainly referring to allergic patients who possess genomic variants contributing to their allergic manifestations. Part III Chapter 11 presents, for the first time, a family with a gain-of-function (GOF) variant in STAT6, causing an early onset severe allergic phenotype. This study provided important pathophysiological insights in patients with monogenic severe allergies early in life and sheds light on the role of STAT6 in allergic diseases.
Finally, in Part IV, the general discussion of the entire thesis covers the current perspectives in IEIs. This knowledge expands further the recognition of the clinical spectrum of IEIs and emphasizes the importance of diagnosing IEI in patients who present with unusual clinical symptoms, enabling the implementation of mechanism-based therapeutic approaches.
Part I of this thesis describes the development of affordable techniques for the diagnosis of IEI. Chapter 2 represents the first study in which WES was applied for genetic testing in the Thai pediatric population suspected of IEI. Importantly, the study revealed novel variants associated with IEIs, which guided to a definite diagnosis and changed the treatment approaches for the tested patients, including the decision to perform the allogeneic stem cell transplantation. The results from this study expand our knowledge of the genotype-phenotype spectrum of IEI.
However, utilizing WES and WGS for genetic analysis in a clinical setting has limitations. These techniques are time-consuming, costly, and involve complex data analysis and interpretation. Due to high costs and limited resources, NGS is not widely available in many developing countries. Therefore, there is a need to explore rapid, robust, and inexpensive molecular tools to address this gap. Chapter 3 describes the development of a rapid, low-cost customized microarray for genetic diagnosis in IEI. This technique demonstrated its promising potential as a first-line screening tool in developing countries. Further, the methods for microarray bioinformatics are reviewed in Chapter 4.
While modern genetic testing methods provides important insights into the pathophysiology of IEI and guides to the therapeutic approach, the analysis starts with simple tests (“basic to the basics”) in order to investigate immunological changes in patients according to their phenotype. International consensus guidelines recommend prompt measurement of serum immunoglobulin (Ig)G in patients suspected of having an antibody deficiency. However, in many developing countries, even such tests are only available in referral centers and not easily accessible to a substantial number of people. Measurement of total serum globulin levels, routinely assessed in liver biochemistry testing, can be an attractive candidate for screening hypogammaglobulinemia in developing countries. Chapter 5 describes the development of a model that predicts immunoglobulin G levels in children using serum globulin levels combined with the patient's disease status. This model facilitates timely decision-making for initiating immunoglobulin therapy in pediatric patients suspected of hypogammaglobulinemia in developing countries.
The presentation of IEI patients can be very diverse with atypical immunological manifestations and non-immunological comorbidities. Part II of the thesis describes different intriguing cases, demonstrating the diverse clinical spectrum of IEI patients. Chapter 6 describes a patient with hypomorphic DOCK8 variants who exhibited a milder phenotype compared to the typical DOCK8-deficient patients. Making a definite diagnosis is a challenge for such a patient. In comparison, DOCK8 deficiency was diagnosed in another more typical patient (chapter 7) who was experiencing recurrent episodes of different types of hematological malignancies, highlighting the role of DOCK8 in immune surveillance of malignancies. Chapter 8 describes the lifelong clinical course of two sisters with identical damaging NBAS variants, who suffered from combined immunodeficiency, autoimmunity, allergy and malignancy. Chapter 9 describes a patient in whom the innate immune system is affected. Genetic analysis revealed damaging FERMT3 variants. The patient was then diagnosed with leukocyte adhesion deficiency (LAD) type III. However, unexpectedly an impairment of the antibody production was found as well in this patient. This was never reported and indicated a defect in the adaptive immune system. Immunoglobulin replacement therapy led to a dramatic clinical improvement in this patient. Chapter 10 provides insights into a patient with congenital glycosylation disorder and a severe immune deficiency. Novel compound heterozygous variants in PGM3 were found. The longstanding history of this patient with immunodeficiency as well as the recovery time of PGM3 activity after a matched related donor stem cell transplantation is discussed.
Traditionally, allergy has been regarded as a polygenic disease, influenced by genetic susceptibility in the form of single nucleotide polymorphisms (SNPs) that interact with immunomodulating factors in the environment. However, allergy has been recognized as a frequent immunological comorbidity in IEIs. Recently, a new subcategory of IEIs known as "primary atopic disorders" has been proposed, mainly referring to allergic patients who possess genomic variants contributing to their allergic manifestations. Part III Chapter 11 presents, for the first time, a family with a gain-of-function (GOF) variant in STAT6, causing an early onset severe allergic phenotype. This study provided important pathophysiological insights in patients with monogenic severe allergies early in life and sheds light on the role of STAT6 in allergic diseases.
Finally, in Part IV, the general discussion of the entire thesis covers the current perspectives in IEIs. This knowledge expands further the recognition of the clinical spectrum of IEIs and emphasizes the importance of diagnosing IEI in patients who present with unusual clinical symptoms, enabling the implementation of mechanism-based therapeutic approaches.
Original language | English |
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Awarding Institution |
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Supervisors/Advisors |
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Award date | 12 Sept 2023 |
Place of Publication | Rotterdam |
Print ISBNs | 978 90 361 0713 6 |
Publication status | Published - 12 Sept 2023 |