Clinical, immunological and genetic characteristic of patients with clinical phenotype associated to LRBA-deficiency in Colombia / Características clínicas, inmunológicas y genéticas de pacientes con el fenotipo asociado a deficiencia LRBA en Colombia

Abstract Background: LPS-responsive beige -like anchor protein (LRBA) deficiency is a primary immunodeficiency disease caused by loss of LRBA protein expression, due to biallelic mutations in LRBA gene. LRBA deficiency patients exhibit a clinically heterogeneous syndrome. The main clinical complication of LRBA deficiency is immune dysregulation. Furthermore, hypogammaglobulinemia is found in more than half of patients with LRBA-deficiency. To date, no patients with this condition have been reported in Colombia Objective: To evaluate the expression of the LRBA protein in patients from Colombia with clinical phenotype associated to LRBA-deficiency. Methods: In the present study the LRBA-expression in patients from Colombia with clinical phenotype associated to LRBA-deficiency was evaluated. After then, the clinical, the immunological characteristics and the possible genetic variants in LRBA or other genes associated with the immune system in patients that exhibit decrease protein expression was evaluated. Results: In total, 112 patients with different clinical manifestations associated to the clinical LRBA phenotype were evaluated. The LRBA expression varies greatly between different healthy donors and patients. Despite the great variability in the LRBA expression, six patients with a decrease in LRBA protein expression were observed. However, no pathogenic or possible pathogenic biallelic variants in LRBA, or in genes related with the immune system were found. Conclusion: LRBA expression varies greatly between different healthy donors and patients. Reduction LRBA-expression in 6 patients without homozygous mutations in LRBA or in associated genes with the immune system was observed. These results suggest the other genetic, epigenetic or environmental mechanisms, that might be regulated the LRBA-expression.

Resumen Antecedentes: la deficiencia de LRBA (del inglés, LPS-responsive beige -like anchor protein) es una inmunodeficiencia primaria causada por la pérdida de la expresión de la proteína LRBA, debido a mutaciones bialélicas en el gen LRBA. Los pacientes con deficiencia de LRBA exhiben un síndrome clínicamente heterogéneo. La principal complicación clínica de la deficiencia de LRBA es la desregulación inmune. Además, la hipogammaglobulinemia se encuentra en más de la mitad de los pacientes con deficiencia de LRBA. Hasta la fecha, no se han reportado pacientes con esta afección en Colombia Objetivo: Evaluar la expresión de la proteína LRBA en pacientes de Colombia con fenotipo clínico asociado a deficiencia de LRBA Métodos: En el presente estudio se evaluó la expresión de LRBA en pacientes de Colombia con fenotipo clínico asociado a deficiencia de LRBA. Después de eso, se evaluaron las características clínicas, inmunológicas y las posibles variantes genéticas en LRBA o en otros genes asociadados con el sistema inmune en pacientes que exhiben una disminución de la expresión de la proteína. Resultados: En total, se evaluaron 112 pacientes con diferentes manifestaciones clínicas asociadas al fenotipo clínico LRBA. La expresión de LRBA varía mucho entre diferentes donantes sanos y pacientes. A pesar de la gran variabilidad en la expresión de LRBA, se observaron seis pacientes con una disminución en la expresión de la proteína LRBA. Sin embargo, no se encontraron variantes bialélicas patógenas o posibles patógenas en LRBA, o en genes relacionados con el sistema inmune. Conclusión: La expresión de LRBA varía mucho entre diferentes donantes sanos y pacientes. Se observó reducción de la expresión de LRBA en 6 pacientes sin mutaciones homocigotas en LRBA o en genes asociados. Estos resultados sugieren los otros mecanismos genéticos, por ejemplo epigenéticos o ambientales, que podrían estar regulados por la expresión de LRBA

Approach to the patient with vitamin D-deficient osteomalacia due to X-linked agammaglobulinemia / 中华内分泌代谢杂志

Osteomalacia is a metabolic bone disease characterized by impaired mineralization of bone matrix. VitaminD deficiency contributes to a decrease in the efficiency of intestinal calcium and phosphorus absorption, resulting in secondary hyperparathyroidism and an inadequate calcium-phosphorus product, thereby causing osteomalacia. We present a patient who was diagnosed as vitamin D-deficient osteomalacia due to X-linked agammaglobulinemia ( XLA) , and the genetic analysis of the BTK gene revealed a missense mutation ( c.82C>T) . It should be attached great importance to etiological analysis of osteomalacia, and XLA may also be a cause of vitamin D deficiency.

Paraparesis, leucodystrophy and brain atrophy are neurological manifestations of congenital immunodeficiency disease? / 中华实用儿科临床杂志

A 4-year-old boy complained of weakness of the lower limbs for one and a half month.The child had been diagnosed as X-linked agammaglobulinemia (XLA) at 1-year old.In recent one and a half month,he gradually suffered from activity intolerance and fatigue,inability to jump and run,staggering gait and slow speech.All the symptoms above indicated deteriorating motor function.The brain magnetic resonance imaging revealed abnormal signals in white matter and brain atrophy.The cerebrospinal fluid analysis detected the presence of oligoclonal immunoglobulin G band.In short term after intravenous immunoglobulin and methylprednisolone treatment,the boy's lower extremity function and speech speed were slightly improved.However,at 1-year follow-up,the boy's condition became even worse.The child could not sit without support and had difficulty in swallowing.The child could not speak or follow any commands.Neurological examination revealed spastic quadriplegia and pseudobulbar palsy.Progressive neurodegeneration is not a common syndrome in patients with XLA.Brain biopsy is an important approach clinically to find out etiology.

X-linked agammaglobulinemia in children / 中华实用儿科临床杂志

X-linked agammaglobulinemia (XLA) is one of the most common types of primary immunodeficiency disease in children,and is an antibody deficiency disease which is seen in men.Most XLA patients carry mutations in Bruton tyrosine kinase (BTK) gene,they typically present with very low numbers of peripheral B cells and a profound deficiency of all immunoglobulin isotypes.XLA is characterized by recurrent bacterial infections within 2 years,sometimes life-threatening.The prognosis of XLA has been improved by the treatment of gammaglobulin that allow normal concentrations of serum IgG.

Agammaglobulinemia ligada al cromosoma X en adultos: Evolucion clínica / X-linked agammaglobulinemia in adults. Clinical evolution

La agammaglobulinemia ligada al cromosoma X (XLA) se caracteriza por la ausencia o reducción significativa de linfocitos B, niveles bajos o indetectables de inmunoglobulinas y, clínicamente, por infecciones principalmente respiratorias por bacterias capsuladas extracelulares y diarrea recurrente. El tratamiento de reemplazo con gammaglobulina ha permitido a la mayor parte de los enfermos llegar a adultos con una buena calidad de vida. Analizamos las características clínicas de 14 pacientes mayores de 18 años con diagnóstico de XLA asistidos en nuestra Unidad desde 2003, fecha en que fue derivado el primer paciente, hasta 2015. La edad promedio en el momento de la derivación fue de 20.4 años, en el momento de la última consulta de 25.5. El tiempo promedio de seguimiento fue de 59.8 meses. Previo al diagnóstico todos habían presentado infecciones, las más frecuentes fueron las respiratorias. Posteriormente al diagnóstico todos iniciaron tratamiento de reemplazo con gammaglobulina endovenosa, y a pesar de que las infecciones disminuyeron en frecuencia y gravedad, en este período se presentaron enfermedades con secuelas graves. Al comenzar el seguimiento en nuestra Unidad, 35.7% presentaban deterioro de la función respiratoria, solo grave en un paciente. Durante el seguimiento ninguno presentó deterioro de la función respiratoria ni complicaciones clínicas importantes. Tres pasaron a gammaglobulina subcutánea con buena tolerancia. El número de adultos con XLA es cada vez mayor, la mayoría llegan a la segunda década de la vida sin complicaciones graves y bajo tratamiento se mantienen libres de enfermedades infecciosas graves y de progresión de sus secuelas pulmonares.

X-linked agammaglobulinemia (XLA) is characterized by absent or severely reduced B cells, low or undetectable immunoglobulin levels and clinically by extracellular bacterial infections which mainly compromise the respiratory tract as well as recurrent diarrheas. The mainstay of treatment is gammaglobulin replacement therapy, which allows most patients to reach adulthood with high quality of life. We analyzed the clinical features of 14 patients over 18 years of age with XLA diagnosis that received treatment in our unit from the year 2003, the date the first patient was derived, until 2015. The average age at which patients were referred was 20.4 years old; age at the last consult was 25.5. The average follow-up time was 59.8 months. Previously to being diagnosed all patients had suffered infections, most frequently respiratory. After diagnosis all were started on intravenous gammaglobulin replacement treatment and in spite of infections being reduced in severity and frequency, there were cases of severe disease with long term sequelae. At the beginning of our follow-up 35.7% presented impaired respiratory function with only one case being severe. In no cases during this period did the respiratory function worsen, nor were there severe clinical complications. Three patients were switched to subcutaneous immunoglobulin treatment with good tolerance. The number of XLA cases is increasing, as most reach the second decade of life without serious complications and remain free of severe infectious disease and further impairment of their respiratory functions with the treatment.

A novel BTK gene mutation, c.82delC (p.Arg28 Alafs*5), in a Korean family with X-linked agammaglobulinemia / 소아과

X-linked agammaglobulinemia (XLA) is a hereditary humoral immunodeficiency that results from Bruton’s tyrosine kinase (BTK) gene mutations. These mutations cause defects in B-cell development, resulting in the virtual absence of these lymphocytes from the peripheral circulation. Consequently, this absence leads to a profound deficiency of lg all isotypes, and an increased susceptibility to encapsulated bacterial infections. A 15-month-old Korean boy presented with recurrent sinusitis and otitis media after 6 months of age, and had a family history of 2 maternal uncles with XLA. Laboratory tests revealed a profound deficiency of Ig isotypes, and a decreased count of CD19⁺ B cells in the peripheral circulation. Based on his family history and our laboratory test results, he was diagnosed with XLA. We performed BTK gene analysis of peripheral blood samples obtained from family members to confirm the diagnosis. Mutational analysis revealed a novel hemizygous frameshift mutation (c.82delC, p.Arg28Alafs*5), in the BTK gene. His mother and maternal grandmother were heterozygous carriers of this mutation and his two maternal uncles were hemizygous at the same position. After XLA diagnosis, intravenous immunoglobulin (400 mg/kg, monthly) treatment was initiated; recurrent sinusitis and otitis media were subsequently brought under control. To our knowledge, this is the first reported case of a Korean pedigree with a novel mutation in the BTK gene.

Agammaglobulinemia ligada al x o de bruton / X-linked agammaglobulinemia or bruton´s disease

La agammaglobulinemia ligada al X (ALX) o de Bruton es una inmunodeficiencia primaria que generalmente se manifiesta en los primeros meses de la vida, cuando disminuyen las concentraciones séricas de las inmunoglobulinas maternas. Se caracteriza por infecciones recurrentes y ausencia total o niveles muy bajos de inmunoglobulinas. Se reporta el caso de un niño de 5 años de edad con historia de procesos infecciosos severos recurrentes de comienzo a los 18 meses de nacido: shigellosis, infecciones respiratorias bacterianas, bronconeumonías, conjuntivitis, sinusitis, meningoencefalitis en tres ocasiones (dos de etiología viral y una de etiología bacteriana), otitis media supurativa crónica, giardiasis de evolución tórpida y lesiones sépticas en piel por pseudomona aeruginosa y estafilococo dorado. Durante el curso de los procesos infecciosos se diagnosticó una enfermedad autoinmune (psoriasis). El estudio inmunológico realizado mostró niveles extremadamente reducidos de las inmunoglobulinas séricas: IgG 0,00 mg/L (370 - 1 400 mg/L); IgA 0,08 g/L (50 - 230 mg/L); e IgM 0,07 g/L (30 - 170 mg/L), así como células B CD19+ en sangre periférica casi ausentes, con un valor de 0,12 por ciento (VN: 21 - 44 por ciento ). Se estableció el diagnóstico de agammaglobulinemia ligada al X o de Bruton. El paciente recibió tratamiento con inmunoglobulina humana por vía endovenosa con mejoría clínica evidente...

X-linked agammaglobulinemia (XLA) or Bruton disease is a primary immunodeficiency, which typically appears in the first months of life, when serum concentrations of maternal immunoglobulins decrease. It is characterized by recurrent infections and total absence or very low levels immunoglobulin. We report a 5-year-old boy with a history of recurrent severe infectious processes beginning at 18 months of age: shigellosis, bacterial respiratory infections, bronchopneumonia, conjunctivitis, sinusitis, meningoencephalitis three times (two of viral etiology and one of bacterial etiology), chronic suppurative otitis media, giardiasis with torpid evolution and septic skin lesions caused by Pseudomona aeruginosa and Staphylococcus aureus. During the course of infectious processes an autoimmune disease (psoriasis) was diagnosed. Immunological study showed extremely low levels of serum immunoglobulins: IgG 0.00 mg / L (370 - 1 400 mg / L), IgA 0.08 g / L (50 - 230 mg / L), and IgM 0, 07 g / L (30 - 170 mg / L) and CD19 + B cells in peripheral blood almost absent, with a value of 0.12 percent (VN: 21 - 44 percent). Diagnosis of X-linked agammaglobulinemia or Bruton disease was established. The patient was treated with intravenous human immunoglobulin with obvious clinical improvement...

Three cases report and literature review of X-Linked agammaglobulinemia / 临床儿科杂志

Objective To analyze the clinical features, diagnosis and treatment of X-Linked Agarnmaglobulinemia (XLA). Methods Clinical features, cellular and humoral immune functions, treatment and prognosis from 3 patients with XLA were retrospectively reviewed. Results The age of onset were from 11 months to 6 years in these 3 cases, however, the median age of diagnosis was 12 years. All patients showed multiple recurrent bacterial infections, arthritis involved large joints such as knee, ankle, elbow and hip. Laboratory examination revealed the decrease of serum gammmaglohulin and absence of B lymphocytes in the peripheral blood. All 3 patients were identiifed BTK mutations, which were frameshift mutation and nonsense mutation in exon 3, frameshift mutation in exon 10, missense mutation in exon 18. After XLA was diagnosed, the patients were managed by intravenous gammagloulin (IVIG) replacement. The non-steroidal anti-inflammatory drugs (NSAIDs) were administrated in patients combined arthritis. The small dose of hormones had been applied. All patients had a significantly improvement. Conclusions The clinical features of XLA have greater variability, with recurrent bacterial infections. Markedly decreased and absent tosils and lymph nodes, serum immunoglobulin may be one of the warning signs for early diagnosis of XLA. IVIG and NSAIDs can be jointly treatment of XLA with arthritis. The steroid and immunosuppressant agents should be used with caution.

Pneumocystis jiroveci Pneumonia in a 5-month-old Boy with Agammaglobulinemia: A Case Report / 대한구급학회지

Pneumocystis jiroveci (P. jiroveci) pneumonia is known as a common opportunistic infection in patients with impaired immunity. Underlying disease or conditions related to the development of P. jiroveci pneumonia include acquired immunodeficiency syndromes, as well as malignancies and congenital immune deficiency disorders. We describe a 5-month-old boy without significant medical history who was admitted at our hospital because of fever, tachypnea, vomiting, diarrhea, and lethargy whose condition became worse within several hours after admission. A chest X-ray showed bilateral diffuse infiltration and high resolution computed tomography showed diffuse bilateral ground-glass opacity. The patient was diagnosed with P. jiroveci pneumonia by direct immunofluorescent antibody staining from lung biopsy and he was later diagnosed with agammaglobulinemia. Although the boy was treated with antibiotics, high-dose corticosteroids and mechanical ventilation, he expired on the 5th hospital day. Here, we report the case of P. jiroveci pneumonia in a boy with agammaglobulinemia.

Clinical manifestations and BTK gene defect in 4 unrelated Taiwanese families with Bruton’s disease.

Background and objective: X-linked agammaglo-bulinemia (XLA, also called Bruton’s disease) is is an X-linked recessive disorder characterized by recurrent bacterial infections, usually occurring in the first few years of life. Here, we report the results of a BTK gene mutation screening study that was performed in Taiwanese families with the BTK gene defect to further understand the inheritance patterns of XLA patients in Taiwan and to avoid new cases of XLA within families. Materials and methods: In this study, 52 members of 4 unrelated Taiwanese families with the BTK gene defect were enrolled. We studied the immunologic reports of 6 symptomatic living male patients with confirmed BTK gene defects and correlated the findings with their clinical symptoms. The genomic DNA of the subjects was subjected to direct sequencing mutation analysis. Results: We screened 52 members of 4 unrelated Taiwanese families with the BTK gene defect for BTK gene mutation and found that there were 6 symptomatic living patients with a confirmed defect, 7 symptomatic deceased patients highly suspected to have had the defect and 11 asymptomatic female carriers. Conclusions: This is the first report in a series of the thorough screening for the BTK mutation and its carrier status in 4 unrelated Taiwanese families. One pedigree of our study comprises 4 generations. A complete BTK gene mutation study for the patient’s family members is strongly suggested.

Mutations of Bruton's tyrosine kinase gene in Brazilian patients with X-linked agammaglobulinemia

Mutations in Bruton's tyrosine kinase (BTK) gene are responsible for X-linked agammaglobulinemia (XLA), which is characterized by recurrent bacterial infections, profound hypogammaglobulinemia, and decreased numbers of mature B cells in peripheral blood. We evaluated 5 male Brazilian patients, ranging from 3 to 10 years of age, from unrelated families, whose diagnosis was based on recurrent infections, markedly reduced levels of IgM, IgG and IgA, and circulating B cell numbers <2 percent. BTK gene analysis was carried out using PCR-SSCP followed by sequencing. We detected three novel (Ala347fsX55, I355T, and Thr324fsX24) and two previously reported mutations (Q196X and E441X). Flow cytometry revealed a reduced expression of BTK protein in patients and a mosaic pattern of BTK expression was obtained from mothers, indicating that they were XLA carriers.

A Case of Gastric Adenocarcinoma in a Patient with X-linked Agammaglobulinemia / 대한소화기내시경학회지

X-linked agammaglobulinemia is a common type of primary immunodeficiency disorder that's caused by mutation of the BTK gene. The absence of B lymphocytes and plasma cells causes recurrent infections. Patients with X-linked agammaglobulinemia also have a high risk for developing hematological malignancies and, to a lesser degree, carcinoma. We report here on a 26-years-old male patient who suffered with X-linked agammaglobulinemia that was caused by BTK gene mutation, and he developed a gastric cancer in the antrum. He was noted to have chronic atrophic gastritis and diffuse intestinal metaplasia on the endoscopic examination that was done 7 years previously. We recommend regular esophagogastroduodenoscopic evaluation for a patient with X-linked agammaglobulinemia in order to make an early diagnosis of stomach carcinoma.

A Case of Rectal Cancer in a Patient with X-linked Agammagloubulinemia / 대한소화기내시경학회지

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disorder caused by germline mutation of the Bruton tyrosine kinase (BTK) gene. Most of the patients diagnosed X-LA suffer from recurrent infections of the respiratory and gastrointestinal tracts. Increased risk of malignancy in X-LA patients include lymphoma, gastric cancer, colorectal cancer. We report a case of 32-years-old male patient with X-linked agammagolbulinemia and rectal cancer. Agammaglobulinemia was diagnosed at 13 years old. He underwent colonoscopy for hematochezia. An ulceroinfiltrative mass was found during colonscopy and biopsy revealed moderately differentiated adenocarcinoma. Subsequently, he underwent a anterior resection.

A Clinical Study of Primary Immunodeficiency Disease in a Single Center in Seoul from 1996 to 2004 / 소아알레르기및호흡기학회지

PURPOSE: Although primary immunodeficiency disorders are relatively rare, early diagnosis provides the opportunity to reduce morbidity and mortality. The aim of this study was to investigate disease distribution, clinical manifestations, genetic mutation, treatment and prognosis of primary immunodeficiency disorders of childhood. METHODS: We retrospectively reviewed the medical records of 15 cases with primary immunodeficiency disorders between 1996 and 2004 in Samsung Seoul Hospital, Seoul, Korea. RESULTS: The most common primary immunodeficiency was common variable immunodeficiency (CVID) (n=7), followed by X-linked agammaglobulinemia (XLA) (n=3), severe combined immunodeficiency (SCID) (n=2), hyper IgM syndrome (n=1), selective IgA deficiency (n=1), and chronic granulomatous disease (CGD) (n=1). Most cases had recurrent infections such as otitis media, bacterial pneumonia, sinusitis and other respiratory infections during infancy. The age at diagnosis ranged from 4 months to 17 years with a median age of 5 years. The male to female ratio was 11 to 4. Eleven patients were diagnosed with primary immunodeficiency diseases following respiratory infection, while the other 4 patients had pulmonary tuberculosis, perianal abscess, bacterial meningitis, septic arthritis. All the patients with XLA and CVID were regularly treated with IVIG. Two cases of SCID underwent successful bone marrow transplantation without complications. The patients with hyper IgM syndrome died due to severe infection even after bone marrow transplantation. CONCLUSION: Fifteen variable cases of primary immunodeficiency were diagnosed during 9 years. A high index of suspicion is required in children with recurrent or severe infections for the diagnosis of primary immunodeficiency, because early diagnosis and treatment can reduce mortality and morbidity.

A Case of X-Linked Agammaglobulinemia Associated with Severe Neutropenia / 소아알레르기및호흡기학회지

X-linked agammaglobulinemia(XLA) is characterized by markedly reduced number of B lymphocytes, panhypogammaglobulinemia, recurrent bacterial infections in the first few years of life because of genetic defect for Bruton's tyrosine kinase at Xq22 region. Although XLA is a typical humoral immunodeficiency disease, severe neutropenia is sometimes presented in acute infection phase. We report a 23-month-boy with XLA who presented prolonged pneumonia, severe neutropenia over one month and profound panhypogammaglobulinemia. As his pneumonia improved, neutropenia subsided, but panhypogammaglobulinemia sustained. He was confirmed to have a point mutation in Btk-gene by direct-sequencing of Btk-gene.

Characterization of Bruton's Tyrosine Kinase Genetic Mutations in One Korean X-linked Agammaglobulinemia Family

PURPOSE: X-linked agammaglobulinemia(XLA) is an immunodeficiency caused by abnormalities in Bruton's tyrosine kinase(Btk), and is characterized by a deficiency of peripheral blood B cells. We studied the cytoplasmic expression of Btk protein and analyzed the Btk gene in peripheral blood mononuclear cells from two siblings and one cousin with XLA, as well as additional family members. METHODS: Btk protein expression was analyzed by flow cytometry. Isolation of the coding sequence of the Btk gene was performed by amplification using the reverse transcription-polymerase chain reaction(RT-PCR) technique. Sequence alterations were screened by the single-stranded conformation polymorphism(SSCP) method and characterized by standard sequencing protocols. RESULTS: Cytoplasmic expression of Btk protein in monocytes was not detected in three patients with XLA. In addition, Btk protein analysis clearly showed cellular mosaicism in monocytes from four obligate carriers, findings further supported by SSCP. A single base pair mutation(T to C) in Btk-exon three, which encodes the PH domain, was identified in four XLA patients. A diagnostic sequencing analysis was established to detect heterozygotic pattern in 4 carrier females. Furthermore, we found significant clinical heterogeneity in individuals with the same gene mutation. CONCLUSION: The implicating genetic alteration provided valuable clues to the pathogenesis of XLA in Korea and the flow cytometric analysis was suggested as a useful tool for rapid detection of XLA patients and carriers. The present study has identified a genetic mutation in the Btk coding region and demonstrated heterogeneity in clinical manifestations among patients with the same mutation. A flow cytometric analysis was found to be informative in establishing a deficiency of Btk protein in both patients and carriers and is recommended as a frontline procedure in the molecular diagnosis and work-up of XLA.

Protein and Genetic Analysis of Bruton's Tyrosine Kinase(Btk) in Three Korean X-linked gammaglobulinemia(XLA) Families

PURPOSE: Mutations in the Bruton's tyrosine kinase(Btk) gene are responsible for X-linked agammaglobulinemia(XLA), an immunodeficiency caused by a block in B cell differentiation. In this report we characterize the protein expression and genetic mutations of Btk in four Korean patients with three unrelated XLA families. METHODS: The resulting Btk proteins were characterized by a flow cytometry and the mutations were analyzed using single strand conformation polymorphism(SSCP) and direct sequencing. RESULTS: Two deletions, including one novel genetic alteration, and one splicing error, were found in these three XLA families. Along with the identification of mutations, Btk protein analysis using flow cytometry clearly showed cellular mosaicism in monocytes from five obligate carriers, findings consistent with those by SSCP. We attempted to determine the origin of mutation in an XLA family with a novel 4-bp deletion of exon eight, suggesting a germline mutation in this family. In addition, we found some clinical heterogeneities in the affected brothers with the same gene mutation. CONCLUSION: These identified genetic alterations provided valuable clues to the pathogenesis of XLA in Korea. The flow cytometric analysis is suggested as a useful tool for rapid detection of XLA patients and carriers.

Characterization of Mutations in Bruton's Tyrosine Kinase(Btk)Gene from Unrelated 3 X-linked Agammaglobulinemia(XLA) Families in Korea

PURPOSE: X-linked agammaglobulinemia(XLA) is an immunodeficiency caused by abnormalities in Bruton's tyrosine kinase(Btk), and is characterized by a deficiency of peripheral blood B cells. We studied cytoplasmic expression of Btk protein and analyzed the Btk gene in peripheral blood mononuclear cells(PBMC) from three XLA families in Korea. METHODS: Heparinized venous blood samples were collected from four XLA patients and additional family members in three unrelated XLA families. Mononuclear cells were separated from their blood and the intracellular Btk protein was characterized by a flow cytometry. The mutation analysis was performed using direct sequencing. RESULTS: Cytoplasmic expression of Btk protein in monocytes was not detected in the patients with XLA. We observed a novel deletion and two point mutations within introns(intron 1 and intron 18) resulting in alternative splicings. In XLA family 2, a 980 bp deletion(from intron 9+191 T to intron 10-215 C) including exon 10 was found in patient P2. He was the only sporadic case in this study, because his mother and brother showed a normal Btk expression by flow cytometry. CONCLUSION: These identified genetic alterations support the molecular heterogeneity of Btk gene in XLA disease. Additionally, by means of flow cytometric analysis, we diagnosed three hypogammaglobulinemia patients as XLA. Advancements in diagnostic methods has facilitated a prompt and definite diagnosis of this disease.

Hepatocellular Carcinoma Following Vertical Transmission of Hepatitis B Virus in a Child with X-linked Agammaglobulinemia / 대한소아소화기영양학회지

X-linked agammaglobulinemia (XLA) is a primary inherited B-cell immunodeficiency. The prevalence of neoplastic disease in patients with XLA is approximatedly 0.7%. The most frequent tumor is lymphoreticular malignancy. We report a case of hepatocellular carcinoma (HCC) in a 13-year-old boy with XLA, after probable maternal transmission of hepatitis B virus. The authors consider that the vertical transmission of hepatitis B virus might play an important role in the development of HCC in a child with XLA who could not eliminate hepatitis B virus effectively.

Identification of a Novel Mutation of Bruton's Tyrosine Kinase(BTK)Gene in a X-linked Agammaglobulinemia(XLA) Family

X-linked agammaglobulinemia(XLA) is a heritable humoral immunodeficiency disease characterized by inefficient expansion of pre-B cells into later B cell stages or incomplete differentiation of B cell precursors to pre-B cells. The gene mutated in XLA was identified as a cytoplasmic tyrosine kinase, named Bruton's tyrosine kinase(BTK). In this report we investigated the characteristics of immune cells, the patterns of intracellular BTK protein expression by flow cytometry, and the genetic abnormality by direct sequencing in one Korean XLA family. Finally, we found that the serum immunoglobulins and the number of peripheral B cells were extremly low in the patient and his brother. The histogram of intracellular BTK staining in the patient and his brother showed typical case of XLA, whereas that of their mother showed a carrier pattern. We also identified a novel point mutation in the first intron of the BTK gene in the patient and his brother. The genomic DNA sequencing of mother and sister showed a G/A heterozygote pattern. These results will provide valuable clues to the pathogenesis of XLA, and suggest an approach useful for carrier detection.