X linked agammaglobulinaemia with a 'leaky' phenotype.

Typical X linked agammaglobulinaemia (XLA) is characterised by absence of immunoglobulin production and lack of mature B cells. The gene responsible for XLA has recently been identified, and codes for a B cell tyrosine kinase, BTK. A family affected by a B cell immunodeficiency, which is less severe than classical XLA, is described but they had a pedigree suggestive of X linked inheritance. Demonstration of a mutation in the BTK gene confirms that this is a mild form of XLA.     

X linked lymphoproliferative disease in a United Kingdom family

X linked lymphoproliferative disease (XLP; Duncan's disease) is a rare disorder affecting boys and characterised by a defective immune response to Epstein-Barr virus caused by a mutation in a gene located at chromosome Xq25. Three siblings with XLP in a single UK family are reported and the variation in phenotypic expression of the disease in these siblings described. One of the siblings with life threatening fulminant infectious mononucleosis was successfully treated by chemotherapy, followed by bone marrow transplantation using an unaffected brother as the donor. A healthy baby boy recently born into the family was identified as carrying the defective maternal X chromosome using molecular genetic linkage analysis. This family illustrates the extent of present understanding of this often fatal condition.     

Coxsackie B3 virus encephalitis in a patient with agammaglobulinaemia

A 19-month-old boy with agammaglobulinaemia contracted a Coxsackie B3 virus infection which caused meningoencephalitis. His neurological status deteriorated over the following 4 years and he died aged 6 years. Treatment with gammaglobulin i.m. and IgG-Fab₂ fragments i.v. was not effective. Enterovirus can cause life-threatening infections in immunodeficient patients.Abbreviations AG agammaglobulinaemia - ECHO enteric cytopathic human orphan - ME meningoencephalitis     

New X linked mental retardation syndrome

IntroductionResearching inherited mental retardation, from a diagnostic and aetiological point of view, is a great challenge. A particular type of mental retardation is the one linked to the X chromosome which is classified under syndromic and non-syndromic types, according to the presence or absence of a specific physical, neurological or metabolic pattern associated with mental retardation.Patients and methodFive generations of a family have been studied with eight males suffering from mental retardation. Six of these males were clinically tested using anthropometric indicators and genetic tests: high resolution karyotypes, fragile X research, linkage and MID1 and PQBP1 gene studies.ResultsAlong with mental retardation, the clinical study showed a pattern of microcephaly, micrognathia, osteoarticular and genital anomalies, short stature and other less frequent malformations. The linkage study mapped the possible causal gene of this mental retardation syndrome and multiple congenital abnormalities in the Xp11.23-q21.32 segment, with a LOD score of 2. As far as we know, a medical profile, similar to the one these patients have, linked to this X segment has not been described.ConclusionsWe suspect that this family has a “new syndrome” of mental retardation and multiple congenital anomalies linked to the X chromosome.     

Early onset agammaglobulinaemia with monoclonal IgG production

Two patients are described with X-linked agammaglobulinaemia (XLA). After a period of gammaglobulin infusions endogenous IgG production appeared to resume and gammaglobulin therapy was gradually stopped. However, bacterial respiratory tract infections recurred. Immunological evaluation showed normal levels of serum IgG with mono/ oligoclonal IgG m-bands, while B lymphocytes and plasma cells were absent from the peripheral blood and bone marrow. Endogenous IgG was synthesized in plasma cells in the submucosa of the gastrointestinal tract. Renewed high doses of exogenous gammaglobulin led to the reduction of infections and the disappearance of mono/oligoclonal m-bands in the serum. We suggest that as a rare complication of XLA some pre-B-cells may escape the blockade to B-cell maturation and produce mono/oligoclonal IgG, possibly due to chronic infectious stimulation.Abbreviations Ig immunoglobulin - XLA X-linked agammaglobulinaemia     

X chromosome inactivation analysis to distinguish sporadic cases of X-linked agammaglobulinaemia from common variable immunodeficiency

The X chromosome inactivation analysis of eight female relatives was performed to elucidate the X chromosome gene defect of six male hypogammaglobulinaemic individuals. The patients had diminished numbers of circulating B-cells and no relevant family history. The methylation status of three X-linked genes, phosphoglycerate kinase, hypoxanthine phosphoribosyl transferase and DXS255, was determined on DNA from Epstein-Barr virus-transformed B-cell lines established from the female relatives. The methylation pattern of at least one gene was informative in all eight females examined. While both alleles were equally methylated in four of eight females, the remaining four female relatives of three hypogammaglobulinaemia patients exhibited a non-random methylation pattern in their B-cells, suggesting that these three patients represented sporadic cases of X-linked agammaglobulinaemia (XLA). The clinical or immunological status of these three patients did not differ from the remaining two who had early onset hypogammaglobulinaemia and who were tentatively diagnosed as having common variable immunodeficiency. The sixth patient had recurrent infections after undergoing surgical removal of a brain tumour at 22 years of age, although his immunological features did not distinguish him from the other patients. X chromosome inactivation analysis can be useful in differentiating XLA from hypogammaglobulinaemia in male patients.     

The Prader-Willi phenotype of fragile X syndrome

The Prader-Willi phenotype (PWP) of fragile X syndrome (FXS) is associated with obesity and hyperphagia similar to Prader-Willi syndrome (PWS), but without cytogenetic or methylation abnormalities at 15q11-13. Thirteen cases of PWP and FXS are reported here that were identified by obesity and hyperphagia. Delayed puberty was seen in 5 of 9 cases who had entered puberty, a small penis or testicles in seven of 13 cases, and infant hypotonia and/or a poor suck in seven of 13 cases. Autism spectrum disorder occurred in 10 of 13 cases, and autism was diagnosed in seven of 13 cases. We investigated cytoplasmic interacting FMR1 protein (CYFIP) expression, which is a protein that interacts with FMR1 protein (FMRP) because the gene for CYFIP is located at 15q11-13. CYFIP mRNA levels were significantly reduced in our patients with the PWP and FXS compared to individuals without FXS (p < .001) and also individuals with FXS without PWP (p = .03).     

17例X连锁无丙种球蛋白血症临床表型分析

目的：分析17例单中心临床诊断的X连锁无丙种球蛋白血症（X-linked agammaglobulinemia, XLA）的临床表型特点。方法：2000年1月至2007年4月北京儿童医院住院患儿,根据临床反复感染表现、血IgG<2g/L、外周血成熟B淋巴细胞缺失或明显降低（<1%）诊断为XLA者,分析临床特点,总结规律。结果：首次诊断年龄平均为7.7岁,88.2%患儿首次诊断年龄>6岁。首次出现症状年龄平均为4.2岁,11.8%患儿首次出现症状年龄<1岁,17.6%患儿首次出现症状年龄为1~2岁。64.7%患儿首发症状为呼吸系统感染,大部分患儿均以此为主诉入院。35.3%患儿有关节炎表现。皮肤及软组织感染少见于<1岁年龄组。大年龄组患儿可出现突发败血症和/或深位部感染。结论：该组患儿发病年龄及首次诊断年龄均较迟,呼吸系统感染为最常见的主诉,关节炎的比例较高。>1/2的患儿血CD4+T细胞减少,CD8+T细胞增加,CD4/CD8比例倒置,NK细胞减少。     

Ichthyosis linked to the X chromosome. Biochemical and endocrinologic study

The case of a 6-year-old male patient suffering from X-chromosome-linked ichthyosis is presented. There was no steroid sulfatase activity in the proband's leucocytes and cutaneous fibroblasts. The activity was decreased in the proband's mother's leucocytes and in one brother, affected by a mild ichthyosis. Basal plasma levels of dehydroepiandrosterone and its sulfate were normal for the patient's age, suggesting that sulfates do not play a significant role in the production of free steroids. After 3 intramuscular injections of 1,500 units of human chorionic gonadotropin, plasma levels of testosterone increased normally, indicating that there was no associated primary gonadal insufficiency.     

Neurofibromatosis presenting with a cherubism phenotype

We report on a child who presented clinical manifestations of both neurofibromatosis type 1 (NF1) and cherubism. With genetic testing, we found a mutation in the NF-1 gene, confirming the neurocutaneous disorder. Histology when correlated with radiological evaluation of a mandibular biopsy was consistent with cherubism. This is the first report in the literature of a child with proven neurofibromatosis type 1 and cherubism without extragnathic lesions. This emphasises that cherubism is a clinical phenotype that can be associated with a number of germline mutations involving SH3BP2, PTPN11 and NF1.     

X linked hypophosphataemia: treatment,height gain,and nephrocalcinosis.

The clinical data of 18 patients with X linked hypophosphataemia were analysed retrospectively. The height data were expressed as SD scores. There was no difference in the final height of patients treated with vitamin D (or 1,25-dihydroxyvitamin D) and phosphate for at least two years (n = 12) and that of 16 hypophosphataemic family members who had never been treated. The mean final SD score (-2.07) of treated patients, however, was significantly higher than the value before treatment (-2.79), which indicated an average absolute height gain of 4-4.5 cm compared with the expected height values. Six of the treated patients developed ultrasonographically detectable nephrocalcinosis with normal renal function. The daily phosphate intake and excretion of patients with nephrocalcinosis was significantly higher than that of patients with normal renal morphology. There was no difference in the doses of vitamin D between the two groups. The average urinary calcium:creatinine ratio of the two groups was similar to and below the hypercalciuric 0.6 mmol:mmol limit. The group with nephrocalcinosis, however, had a higher incidence of hypercalciuric episodes than the group without nephrocalcinosis (12 in 130 observations compared with six in 334 observations, respectively). The benefits and risks of treatment of patients with X linked hypophosphataemia must be further evaluated. The high dose of phosphate seems to be an important factor in the development of nephrocalcinosis in this group of patients.     

Low stature in males with normal phenotype and 45,X/46,XY mosaicism

There is wide variation in the clinical expression of 45,X/46,XY mosaicism. Ninety percent of prenatally diagnosed boys have normal male phenotype at birth, while those diagnosed postnatally show a wide spectrum of phenotypes, ranging from Turner syndrome, mixed gonadal dysgenesis, and male pseudohermaphroditism to apparent normality. We report the clinical, cytogenetic, endocrinologic and histologic findings in three boys with an apparently normal male phenotype and 45,X/46,XY mosaicism who were diagnosed postnatally because of their short stature. With the exception of one patient with Turner stigmata, no other abnormal features were found. No correlation between the proportion of 45,X/46,XY cell lines in blood, gonads and phenotype was found. Both prenatally and postnatally diagnosed boys with normal male phenotype must be followed-up because they can develop late-onset abnormalities, such as dysgenetic testes leading to infertility or neoplastic transformation, and short stature, which could be improved with growth hormone therapy.     

Barth syndrome is associated with a cognitive phenotype

OBJECTIVE: Barth syndrome is a rare, X-linked recessive disorder that affects only boys. The cardinal characteristics include growth retardation, cardioskeletal myopathy, chronic or cyclic neutropenia, and 3-methylglutaconic aciduria. A preliminary study of five young boys with Barth syndrome suggested a distinct cognitive phenotype. METHODS: The present study was designed to explore whether additional evidence for a cognitive phenotype emerged from a larger sample. A psychoeducational assessment battery was administered to 15 boys with Barth syndrome. Data from these boys were compared to data from 15 typically developing boys individually matched on age and grade in school to each of the 15 boys with Barth syndrome. RESULTS: Although boys with Barth syndrome had age-appropriate performance on all measures of reading-related skills, their performance on mathematics and visual spatial tasks was significantly lower than that of boys in the comparison group. Moreover, specific aspects of visual short-term memory also differed from available norms. CONCLUSION: Our findings support the validity of the preliminary findings and reflect a higher incidence of cognitive difficulties in boys with Barth syndrome relative to boys in the comparison group. Coupled with the fatigue regularly experienced by boys with Barth syndrome, our findings indicate that educational support should be implemented during the early school-age years for children with Barth syndrome.