T-cell immunodeficiencies

Development and validation of a 2nd tier test for identification of purine nucleoside phosphorylase deficiency patients during expanded newborn screening by liquid chromatography-tandem mass spectrometry

BACKGROUND

Purine nucleoside phosphorylase (PNP) deficiency has been recently introduced in the newborn screening program in Tuscany. In order to improve the PNP screening efficiency, we developed a 2nd tier test to quantify PNP primary markers deoxyguanosine (dGuo) and deoxyinosine (dIno).

METHODS

Dried blood spots (DBS) samples were extracted with 200 μL of methanol and 100 μL of water (by two steps). Internal standards were added at a final concentration of 10 μmol/L. After extraction, samples were analysed by LC-MS/MS. The chromatographic run was performed in gradient mode by using a Synergi Fusion column.

RESULTS

The assay was linear over a concentration range of 0.05-50 μmol/L (R2>0.999) for dGuo and 0.5-50 μmol/L (R2>0.998) for dIno. Intra- and interassay imprecision (mean CVs) for dIno and dGuo ranged from 2.9% to 12%. Limit of quantitaion (LOQ) were found to be 0.05 μmol/L and 0.5 μmol/L for dGuo and dIno, respectively. The reference ranges, obtained by measuring dGuo and dIno concentrations on DBS, were close to zero for both biomarkers. Moreover, DBS samples from seven patients with confirmed PNP were retrospectively evaluated and correctly identified.

CONCLUSIONS

The LC-MS/MS method can reliably measure dIno and dGuo in DBS for the diagnosis of PNP. Validation data confirm the present method is characterised by good reproducibility, accuracy and imprecision for the quantitation of dIno and dGuo. The assay also appears suitable for use in monitoring treatment of PNP patients.

Distribution, clinical features and molecular analysis of primary immunodeficiency diseases in Chinese children: a single-center study from 2005 to 2011

METHODS

Two hundred three children with genetically proven primary immunodeficiency diseases (PIDs) from 197 unrelated families were enrolled from January 2005 to December 2011.

RESULTS

On the basis of criteria developed by the International Union of Immunological Societies, 79 patients were diagnosed as "other well-defined immunodeficiency syndromes" (38.9%), 62 (30.6%) with "predominant antibody deficiencies," 26 (12.8%) with "congenital defects of phagocyte," 25 (12.3%) with "T- and B-cell immunodeficiency" and 11 (5.4%) with "diseases of immune dysregulation." The median time to the diagnosis was 27.9 months and the patients had a wide range of clinical presentations. In addition, a total of 23 pathogenic genes were identified and 213 mutations were detected, including 42 novel mutations.

CONCLUSIONS

With the increase in the awareness of PIDs and diagnostic competence, more PID patients will be diagnosed and we will be able to more accurately identify the frequency and the distribution of PIDs in the most populous country in the world.

Wheezing in infancy

Several population-based birth cohort studies documented that 30% of children suffer from wheezing during respiratory infections before their third birthday. Infants are prone to wheeze because of anatomic factors related to the lung and chest wall in addition to immunologic and molecular influences in comparison to older children. Viral infections lead to immunologic derangements that cause wheezing both in immunocompetent and immunodeficient infants. Anatomic causes of wheeze may be extrinsic or intrinsic to the airway. Not every wheeze is indicative of asthma but prediction of asthma in persistent wheezers is possible. Testing for allergy in these infants is worthwhile and can be of significant value in avoidable allergens. Treatment of an infant with wheezing depends on the underlying etiology. Response to bronchodilators is unpredictable and a trial of inhaled steroids may be warranted in a patient who has responded to multiple courses of oral steroids, has moderate to severe wheezing, or a significant history of atopy including food allergy or eczema. Ribavirin administered by aerosol, hyper-immune respiratory syncytial virus immunoglobulin (RSV IVIG), and intramuscular monoclonal antibody to an RSV protein have been used for RSV bronchiolitis in infants with congenital heart disease or chronic lung disease.

Severe combined immunodeficiency (SCID): from the detection of a new mutation to preimplantation genetic diagnosis

PURPOSE

To describe the identification of a new mutation responsible for causing human severe combined immunodeficiency syndrome (SCID). In a large consanguineous Israeli Arab family, this served as a diagnostic tool and enabled us to carry out preimplantation genetic diagnosis (PGD). We also demonstrated that PGD for homozygosity alleles is feasible.

METHODS

We carried out genome-wide screening followed by fine mapping and linkage analysis in order to identify the candidate genes. We then sequenced DCLRE1C in order to find the familial mutation. The family was anxious to avoid the birth of an affected child, and therefore, because of their religious beliefs, PGD was the only option open to them. The embryos were biopsied at day 3, and a single blastomere from each embryo was analyzed by multiplex polymerase chain reaction for the SCID mutation and 5 additional polymorphic markers flanking DCLRE1C.

RESULTS

Linkage analysis revealed linkage to chromosome 10p13, which harbors the DNA Cross-Link Repair Protein 1 C (DCLRE1C) ARTEMIS gene. Sequencing identified an 8 bp insertion in exon 14 (1306ins8) of DCLRE1C in all the affected patients; this causes an alteration in amino acid 330 of the protein from cysteine to a stop codon (p.C330X). One cycle of PGD was performed and two embryos were transferred, one homozygous wild-type and one a heterozygous carrier, and healthy twins were born.

CONCLUSIONS

Identifying the familial mutation enabled us to design a reliable and accurate PGD protocol, even in this case of a consanguineous family.

An unconditioned bone marrow transplantation in a child with purine nucleoside phosphorylase deficiency and its unique complication

Purine nucleoside phosphorylase deficiency is a rare immunodeficiency syndrome characterized by recurrent infections, neurological dysfunction, and autoimmunity. Early diagnosis and hematopoietic stem cell transplantation may reverse the dismal prognosis in PNP deficiency. This report presents a new PNP deficiency case successfully transplanted without a conditioning regimen from an HLA-identical family donor, who developed a complication of disseminated BCG infection.

Primary immunodeficiency disorders in Kuwait: first report from Kuwait National Primary Immunodeficiency Registry (2004--2006)

Primary immunodeficiency disorders are heterogeneous group of illnesses that predispose patients to serious complications. Registries for these disorders have provided important epidemiological data and shown both racial and geographical variations. The clinical features of 76 patients with primary immunodeficiency disorders registered in Kuwait National Primary Immunodeficiency Registry from 2004 to 2006 were recorded. Ninety-eight percent of the patients presented in childhood. The prevalence of these disorders in children was 11.98 in 100,000 children with an incidence of 10.06 in 100,000 children. The distribution of these patients according to each primary immunodeficiency category is: combined T and B cell immunodeficiencies (21%), predominantly antibody immunodeficiency (30%), other well defined immunodeficiencies (30%), diseases of immune dysregulation (7%), congenital defects of phagocyte number, function or both (8%), and complement deficiencies (4%). The consanguinity rate within the registered patients was 77%. The patients had a wide range of clinical features affecting different body systems. Primary immunodeficiency disorders are prevalent in Kuwait and have a significant impact into the health system.

Frequency and clinical manifestations of patients with primary immunodeficiency disorders in Iran: update from the Iranian Primary Immunodeficiency Registry

Primary immunodeficiency disorders (PID) are a heterogeneous group of diseases, characterized by an increased susceptibility to infections. A total of 930 patients (573 males and 357 females) are registered in Iranian PID Registry (IPIDR) during three decades. Predominantly antibody deficiencies were the most common (38.4%), followed by congenital defects of phagocyte number and/or function (28.3%), other well-defined immunodeficiency syndromes (17.7%), combined T- and B-cell immunodeficiencies (11.0%), complement deficiencies (2.4%), and diseases of immune dysregulation (2.3%). Common variable immunodeficiency was the most frequent disorder (20.8%), followed by chronic granulomatous disease, ataxia-telangiectasia, btk deficiency, selective IgA deficiency, and T-B-severe combined immunodeficiency. The frequency of other PID disorders was less than 50 in number (<5%). There is an increasing trend in recognition of more PID in the recent years. Construction of such registry is not only important for its epidemiological aspect but also for its role in increasing the physician's knowledge about such disorders.

Distribution and clinical aspects of primary immunodeficiencies in a Taiwan pediatric tertiary hospital during a 20-year period

Recent advances in immunologic techniques have lead to increased recognition of primary immunodeficiencies. A review of patients with suspected immunodeficiencies in a Taiwan tertiary hospital from January 1985 to October 2004 and molecular/genetic analyses done on some patients were investigated. Of the 403 patients selected based on the International Classification of Disease, Ninth Revision, 37 patients with PID (8 females and 29 males) were identified: 17 (46%) with antibody production deficiencies, nine (24%) with defective phagocyte function, four (11%) with combined B and T cell immunodeficiencies, seven (19%) with T cell deficiencies, but none with primary complement deficiencies. Those with secondary immunodeficiencies were excluded from the study. Recurrent sinopulmonary infections (62%) were the most common clinical manifestation, followed by sepsis (57%), severe skin infection (40%), splenomegaly/hepatomegaly (27%), central nervous system dysfunction (22%), chronic diarrhea (22%), and failure to thrive (19%). Seven (19%) patients died, five of infections, one of disseminated intravascular coagulopathy and one of hepatocellular carcinoma. Six novel mutations were found from 11 agreed patients. This is the first report on primary immunodeficiencies in Taiwan covering a 20-year period.

Mutations in genes required for T-cell development:IL7R, CD45, IL2RG, JAK3, RAG1, RAG2, ARTEMIS, and ADA and severe combined immunodeficiency: HuGE review

Severe combined immunodeficiency (SCID) is an inherited immune disorder characterized by T-cell lymphopenia (TCLP), a profound lack of cellular (T-cell) and humoral (B-cell) immunity and, in some cases, decreased NK-cell number and function. Affected children develop severe bacterial and viral infections within the first 6 months of life and die before 1 year of age without treatment. Mutations in any of eight known genes: IL2RG, ARTEMIS, RAG1, RAG2, ADA, CD45, JAK3, and IL7R cause SCID. Mutations in unidentified genes may also cause SCID. Population-based genotype and allelic frequencies of these gene defects have not been measured. Some minimal estimates of SCID prevalence are presented. Currently, hematopoietic stem cell transplants are the standard treatment. In clinical trials, gene therapy has been used to reconstitute immune function in patients with IL2RG and ADA defects. The availability of effective therapies, plus the short asymptomatic period after birth, (when stem-cell transplantation is most effective), make SCID a potentially good candidate for newborn screening. Dried blood spots are currently collected from all infants at birth for newborn metabolic screening. Tests for TCLP on dried blood spots could be developed as a screen for SCID. Because SCID may be unrecognized, with infant deaths from infection attributed to other causes, newborn screening is the only way to ascertain true birth prevalence. Validated tests and pilot population studies are necessary to determine newborn screening's potential for identifying infants with SCID.

Gastrointestinal Manifestations of Non-AIDS Immunodeficiency

Most primary immunodeficiencies are diagnosed in children and, therefore, are managed by pediatricians and pediatric specialists. Generally, internists and adult gastroenterologists only rarely encounter patients with primary immunodeficiency, and have little or no involvement in actual treatment. However, gastroenterologists should be familiar with primary immunodeficiency because 1) current and future therapy for immunodeficiency will allow more patients to survive into adulthood, 2) some primary immunodeficiencies, particularly common variable immunodeficiency, may have their first clinical manifestation in adolescence or early adulthood, and 3) recently it has been hypothesized that Crohn's disease may be an immunodeficiency. Detailed treatment recommendations are not included in this review, as subspecialists in pediatrics, immunology, and hematology manage such treatments. Of far greater importance, even in this treatment-oriented forum, is the enhancement of our awareness of these disorders.

Assessment of the child with recurrent chest infections

The child with recurrent chest infections presents the clinician with a difficult diagnostic challenge. Does the child have a simply-managed cause for their symptoms, such as recurrent viral respiratory infections or asthma, or is there evidence of a more serious underlying pathology, such as bronchiectasis? Many different disorders present in this way, including cystic fibrosis, a range of immunodeficiency syndromes, and congenital abnormalities of the respiratory tract. In some affected children, lung damage follows a single severe pneumonia: in others it is the result of inhalation of food or a foreign body. The assessment of these children is demanding: it requires close attention to the history and examination, and in selected cases, extensive investigations. Early and accurate diagnosis is essential to ensure that optimal treatment is given and to minimise the risk of progressive or irreversible lung damage. The aim of this chapter is to examine the causes of recurrent chest infections and to describe how this complex group of children should be assessed and investigated.