Clinical course of patients with major histocompatibility complex class II deficiency

The clinical course of 10 children who have been diagnosed with major histocompatibility complex (MHC) class II deficiency (bare lymphocyte syndrome) in the UK over the past eight years is described. They have had a generally poor prognosis, with only two of the 10 still alive despite eight attempts at bone marrow transplantation in six patients. Overwhelming viral infection was the predominant cause of death. Alternative transplant strategies or novel therapies are required for these patients.     

Clinical course of patients with major histocompatibility complex class II deficiency.

The clinical course of 10 children who have been diagnosed with major histocompatibility complex (MHC) class II deficiency (bare lymphocyte syndrome) in the UK over the past eight years is described. They have had a generally poor prognosis, with only two of the 10 still alive despite eight attempts at bone marrow transplantation in six patients. Overwhelming viral infection was the predominant cause of death. Alternative transplant strategies or novel therapies are required for these patients.     

Meta‐analysis of hematopoietic stem cell transplantation in major histocompatibility complex class II deficiency

Major histocompatibility complex class II deficiency is a rare case of PID. Specific recommendations for hematopoietic stem cell transplant, the only curative treatment option, are still lacking. This meta‐analysis aims to identify the factors associated with better prognosis in these patients. Thirteen articles reporting 63 patients with major histocompatibility complex class II deficiency that underwent hematopoietic stem cell transplant were included. The median age for hematopoietic stem cell transplant was 18 months. The most common source of transplant was bone marrow, with alternative sources as umbilical cord blood emerging during recent years. The highest proportion of engraftment was seen with umbilical cord. Engraftment was higher in patients with matched donors, with better overall survival in patients with reduced‐intensity conditioning. Graft‐vs‐host disease developed in 65% of the patients, with grades I‐II being the most frequently encountered. There was a higher mortality in patients with myeloablative conditioning and no engraftment. There was an inverse correlation between survival and stage of graft‐vs‐host disease. The main cause of mortality was infectious disease, mostly secondary to viral infections. Ideally, matched grafts should be used, and reduced‐intensity conditioning should be considered to reduce early post‐transplant complications. GVHD and viral prophylaxis are fundamental.     

The mutation 35delG of the gene of the connexin 26 is a frequent cause of autosomal-recessive non-syndromic hearing loss in Morocco]

Mutations of the connexin 26 gene, GJB2, are the most common cause of non syndromic autosomal-recessive hearing loss. One of the GJB2 mutations, the 35delG, is recurrent in European and Mediterranean populations with allelic frequency of at least 70% in patients with hearing loss caused by GJB2 impairment. OBJECTIVES: To determine the prevalence of the 35delG mutation in non-syndromic autosomal-recessive deafness in Morocco. PATIENTS AND METHODS: We looked for the 35delG mutation among 25 non-related Moroccan children suffering from an autosomal recessive hearing loss. A screening for GJB2 mutations, and then a search for GJB6 deletions were carried out among patients who do not bear the 35delG. RESULTS: Twelve patients were homozygous for the 35delG mutation. This mutation was responsible for almost half of the hearing loss among our patients (48%). There was no other GJB2 or GJB6 mutation among 13 patients. CONCLUSION: This study underlines the advantages of a systematic search for this mutation among deaf children when environmental causes are considered irrelevant. The identification of this genetic anomaly signs the etiologic diagnosis of deafness, which allows a relevant genetic advice, and a better treatment of patients.     

Pedigree of the major histocompatibility complex in a family with a neonatal alloimmune thrombocytopenia

Immunization of a mother negative for the platelet-specific antigen P1A1 against the P1A1 antigen of her child induced neonatal alloimmune thrombocytopenia. This prompt immune response occurred in her first pregnancy and we were therefore interested to study whether there is an association with genes located within the major histocompatibility complex. We deduced haplotypes of HLA-A, B, C and DR as well as of complement C2, C4 and Bf in the maternal family members.     

丙酮酸脱氢酶缺乏症PDHA1基因的一个新突变及其致病性鉴定

目的研究丙酮酸脱氢酶缺乏症发病分子遗传学机制,从基因水平诊断丙酮酸脱氢酶缺乏症,为遗传咨询和产前基因诊断提供依据。方法对临床表现及实验室检查符合丙酮酸脱氢酶缺乏症的1例患儿采用PCR法对PDHA1基因的11个外显子及外显子交界区进行扩增,并通过对扩增产物直接测序检测突变。采用生物信息学方法对新突变进行氨基酸保守型分析,预测蛋白二、三级结构,鉴定其致病性。结果先症者PDHA1基因第11外显子出现小片段重复突变,即c.1111_1158dup48bp,为新发突变。50例正常对照直接测序均未检测到c.1111_1158dup48bp突变。蛋白质二级、三级结构预测结果显示:新突变c.1111_1158dup48bp引起Ser371_Phe386的16个氨基酸重复,导致蛋白质二、三级结构发生明显变化,而正常对照无此变化。结论 PDHA1基因c.1111_1158dup48bp重复突变不是多态性变异,可能是一种新的致病性突变,导致丙酮酸脱氢酶缺乏症的发病。     

肉碱棕榈酰转移酶Ⅱ缺乏症家系CPT2基因突变分析及产前诊断

分析肉碱棕榈酰转移酶Ⅱ（CPTⅡ）缺乏症患儿及其父母CPT2基因突变类型,为家系成员提供遗传咨询及产前诊断。先证者,女,于3个月时发烧8 h入院,血液酯酰肉碱谱分析显示棕榈酰肉碱显著增高,提示CPTⅡ缺乏症。收集患儿临床资料,采集患儿和父母外周血,提取基因组DNA,应用直接测序法进行CPT2基因5个外显子编码区及与外显子交界的部分内含子区域进行测序。患儿母亲于妊娠中期采取羊水,分取羊水细胞进行CPT2基因突变分析。Sanger测序发现先证者CPT2基因存在两个已知致病突变c.886C > T（p.R296X）和c.1148T > A（p.F383Y）,突变来自父母双方。母亲第二胎羊水细胞CPT2基因存在c.886C > T（p.R296X）,为致病基因携带者。胎儿出生后血液酯酰肉碱谱正常,发育正常。通过家系CPT2基因分析,证实了先证者死因为CPTⅡ缺乏症,在突变明确的前提下,成功地进行了下一胎同胞的产前诊断,为该家庭提供帮助。     

Homozygosity for a mutation in the CYP11B2 gene in an infant with congenital corticosterone methyl oxidase deficiency type II

Isolated aldosterone synthase deficiency can be the source of life‐threatening salt wasting and failure to thrive in infancy. We studied an infant with failure to thrive and persistent hyponatremia despite oral sodium supplementation. Initial analyses revealed highly elevated plasma renin but normal values of plasma aldosterone. The biochemical diagnosis of corticosterone methyl oxidase deficiency type II was established by multisteroid analysis, revealing a pathognomonic pattern with a highly elevated ratio of 18‐OH‐corticosterone to aldosterone. This reflects an enzymatic defect in the aldosterone synthase that is responsible for the terminal steps in the aldosterone biosynthesis. Molecular genetic analysis supported the diagnosis revealing homozygosity for a pathogenic c.554C>T (p.T185I) variation in exon 3 of the CYP11B2 gene encoding aldosterone synthase. Homozygosity for two other polymorphic variations c.504C>T (p.F168F) and c.518A>G (p.K173R) were identified as well. Treatment with fludrocortisone resulted in catch‐up growth. Discontinuation of treatment at the age of 9 years was later possible without any clinical or biochemical deterioration. Conclusions: Isolated deficiency in aldosterone biosynthesis should be considered in neonates and infants with failure to thrive and salt wasting. Normal levels of plasma aldosterone compared with highly elevated levels of plasma renin indicate an impaired aldosterone biosynthesis and suggest the disorder. Recognition of its existence is important as fludrocortisone replacement therapy effectively normalizes sodium balance and growth.     

Aarskog-Scott syndrome: a novel mutation in the FGD1 gene associated with severe craniofacial dysplasia

Aarskog syndrome (AAS) is an X-linked human disease that affects the skeletal formation and embryonic morphogenesis and is caused by mutations in the FGD1 gene. Patients typically show distinctive skeletal and genital developmental abnormalities, but a broad spectrum of clinical phenotypes has been observed. We report here on the clinical and molecular analysis of a family that reveals a novel FGD1 mutation in a 9-year-old boy displaying extreme craniofacial dysplasia associated with attention deficit hyperactivity disorder. Sequencing of FGD1 revealed a novel mutation in exon 7 at position c.1468 C > T in the index patient, leading to a stop codon in the highly conserved RhoGEF gene domain. His mother and maternal grandmother were also found to be heterozygous for this FGD1 mutation. Conclusion: Our results identify a novel mutation of FDG1 in a family with Aarskog syndrome and underscore the phenotypical variability of this condition.     

Kupffer cell engraftment across the major histocompatibility barrier in mice: bone marrow origin, class II antigen expression, and antigen-presenting capacity

The source of population renewal for Kupffer cells (KC), the major antigen-presenting cells of the liver, remains controversial. Using a well-described murine bone marrow transplantation (BMT) model in which the donor and recipient are disparate at the major histocompatibility complex (MHC), we have studied (a) the source of KC renewal by genotypic analysis, cell surface (class II or Ia) antigens, and immune function assays; (b) the level of KC Ia expression post-BMT in transplant recipients; and (c) the capacity of newly repopulating KC to present antigen to an Ia-restricted T cell clone of donor Ia type. Kupffer cell engraftment, as assessed by each of these three methods, was noted to be predominantly of donor marrow origin by day 21 post-BMT. Cell surface Ia expression was comparable to that of nontransplanted controls of the same strain as donor mice. Within 7 days post-BMT, KC were mature antigen-presenting cells. We conclude that KC rapidly repopulate the liver from donor bone marrow post-BMT, and these macrophages are able to interact with T lymphocytes in an immunocompetent manner.     

Hyperinsulinism of infancy associated with a novel splice site mutation in the SCHAD gene

Fatty acids play an important role in regulating insulin secretion, but the mechanisms are unclear. We report a case of a novel splice site mutation in the short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) gene associated with hyperinsulinism. This mutation resulted in a nearly complete absence of immunoreactive protein and a decrease in fibroblast SCHAD activity.     

Direct detection of a major mutation responsible for phenylketonuria in the population of the Federal Republic of Germany

Forty-six individuals having phenylketonuria (PKU) alleles at the phenylalanine hydroxylase (PAH) locus were tested for the haplotype 2 PKU mutation by allele-specific hybridization following in vitro DNA amplification. Patients and carriers previously shown to have a mutant haplotype 2 PAH allele demonstrated conservation of this mutation. In vitro DNA amplification greatly facilitated this analysis and provides the possibility of population screening for 37% of the mutant German PAH alleles.     

Novel compound heterozygous mutation of the MC2R gene in a patient with familial glucocorticoid deficiency

Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterised by glucocorticoid insufficiency without mineralocorticoid deficiency. Here, we report a 2 year-old girl with FGD, showing tall stature and skin pigmentation, but no abnormalities of the external genitalia. Serum sodium, potassium and chloride levels were within normal ranges. Endocrinological analysis revealed low serum cortisol (<5.5 nmol/1), elevated plasma ACTH (875.2 pmol/1) and low 17alpha-hydroxyprogesterone (< 0.303 nmol/l). We suspected the patient of having FGD type 1. Direct and allele-specific sequence analyses of the melanocortin 2 receptor gene (MC2R) revealed compound heterozygous mutations (C21Y and R146H) in the MC2R gene. Her father and mother each had heterozygous C21Y and R146H mutations, respectively, without symptoms of glucocorticoid deficiency. This is the first report of FGD associated with a compound heterozygous mutation of C21Y and R146H in the MC2R gene.     

Severe muscle-eye-brain disease is associated with a homozygous mutation in the POMGnT1 gene.

Muscle-eye-brain (MEB) disease is an autosomal recessive disorder characterized by a broad clinical spectrum including congenital muscular dystrophy, ocular abnormalities, and brain malformation (type-II lissencephaly). Herein, we report on two Turkish siblings with a homozygous mutation in the POMGnT1 gene. A 6-year-old sibling has a severe form of MEB disease, which in some aspects is more suitable with the diagnosis of Walker-Warburg syndrome. However, the same mutation resulted in a less severe form of MEB in the older sibling, who is 14 years old. These two cases suggest that POMGnT1 mutations may cause MEB disease with different phenotypes even in the same family.     

Thyrotoxic periodic paralysis associated with a mutation in the sodium channel gene SCN4A

Thyrotoxic hypokalemic periodic paralysis (THypoKPP) is an uncommon disorder with an unknown etiology. We describe a family in which the proband presented with paralysis and thyrotoxicosis. Because of similarities between familial hypokalemic periodic paralysis (FHypoKPP) and THypoKPP, we sequenced exon 12 of the SCN4A gene, which is known to be mutated in FHypoKPP. We identified an Arg672Ser mutation in the proband and his affected father, as well as the proband's brother. As the brother has paralysis without thyrotoxicosis, our finding suggests that the genetic spectrum of FHypoKPP and THypoKPP overlap. We speculate that thyroid hormone may exert a threshold or permissive effect in hypokalemic periodic paralysis. Non-thyrotoxic family members of individuals with THypoKPP may have an unrecognized risk for paralysis.     

Trimethoprim-sulfamethoxazole induced prolonged hypoglycemia in an infant with MHC class II deficiency: diazoxide as a treatment option

Hyperinsulinemic hypoglycemia associated with trimethoprim-sulfamethoxazole (TMP-SMX) has generally been reported in adults who had renal impairment or in patients with AIDS using high dose TMP-SMX. We present a 5 month-old infant with immunodeficiency due to major histocompatibility complex class II expression defect, developing hypoglycemic convulsion on the third day of high dose TMP-SMX administration. High insulin and C-peptide levels were documented at the time of hypoglycemia. To overcome hypoglycemia while TMP-SMX tapered off, diazoxide was administered which resolved hypoglycemia in 2 months.