Pharmacological Chaperoning: A Potential Treatment for PMM2‐CDG

The congenital disorder of glycosylation (CDG) due to phosphomannomutase 2 deficiency (PMM2‐CDG), the most common N‐glycosylation disorder, is a multisystem disease for which no effective treatment is available. The recent functional characterization of disease‐causing mutations described in patients with PMM2‐CDG led to the idea of a therapeutic strategy involving pharmacological chaperones (PC) to rescue PMM2 loss‐of‐function mutations. The present work describes the high‐throughput screening, by differential scanning fluorimetry, of 10,000 low‐molecular‐weight compounds from a commercial library, to search for possible PCs for the enzyme PMM2. This exercise identified eight compounds that increased the thermal stability of PMM2. Of these, four compounds functioned as potential PCs that significantly increased the stability of several destabilizing and oligomerization mutants and also increased PMM activity in a disease model of cells overexpressing PMM2 mutations. Structural analysis revealed one of these compounds to provide an excellent starting point for chemical optimization since it passed tests based on a number of pharmacochemical quality filters. The present results provide the first proof‐of‐concept of a possible treatment for PMM2‐CDG and describe a promising chemical structure as a starting point for the development of new therapeutic agents for this severe orphan disease.     

ALG11‐CDG syndrome: Expanding the phenotype

ALG11‐Congenital Disorder of Glycosylation (ALG11‐CDG, also known as congenital disorder of glycosylation type Ip) is an inherited inborn error of metabolism due to abnormal protein and lipid glycosylation. We describe two unrelated patients with ALG11‐CDG due to novel mutations, review the literature of previously described affected individuals, and further expand the clinical phenotype. Both affected individuals reported here had severe psychomotor disabilities and epilepsy. Their fibroblasts synthesized truncated precursor glycan structures, consistent with ALG11‐CDG, while also showing hypoglycosylation of a novel biomarker, GP130. Surprisingly, one patient presented with normal transferrin glycosylation profile, a feature that has not been reported previously in patients with ALG11‐CDG. Together, our data expand the clinical and mutational spectrum of ALG11‐CDG.     

Novel variants and clinical symptoms in four new ALG3‐CDG patients,review of the literature,and identification of AAGRP‐ALG3 as a novel ALG3 variant with alanine and glycine‐rich N‐terminus

ALG3‐CDG is one of the very rare types of congenital disorder of glycosylation (CDG) caused by variants in the ER‐mannosyltransferase ALG3. Here, we summarize the clinical, biochemical, and genetic data of four new ALG3‐CDG patients, who were identified by a type I pattern of serum transferrin and the accumulation of Man₅GlcNAc₂‐PP‐dolichol in LLO analysis. Additional clinical symptoms observed in our patients comprise sensorineural hearing loss, right‐descending aorta, obstructive cardiomyopathy, macroglossia, and muscular hypertonia. We add four new biochemically confirmed variants to the list of ALG3‐CDG inducing variants: c.350G>C (p.R117P), c.1263G>A (p.W421*), c.1037A>G (p.N346S), and the intron variant c.296+4A>G. Furthermore, in Patient 1 an additional open‐reading frame of 141 bp (AAGRP) in the coding region of ALG3 was identified. Additionally, we show that control cells synthesize, to a minor degree, a hybrid protein composed of the polypeptide AAGRP and ALG3 (AAGRP‐ALG3), while in Patient 1 expression of this hybrid protein is significantly increased due to the homozygous variant c.160_196del (g.165C>T). By reviewing the literature and combining our findings with previously published data, we further expand the knowledge of this rare glycosylation defect.     

Identification of four novel PMM2 mutations in congenital disorders of glycosylation (CDG) Ia French patients

We screened 11 unrelated French patients with congenital disorders of glycosylation (CDG) Ia for PMM2 mutations. Twenty one missense mutations on the 22 chromosomes (95%) including four novel mutations were identified: C9Y (G26A) in exon 1, L32R (TA95GC) in exon 2, and T226S (C677G) and C241S (G722C) in exon 8. We studied the PMM activity of these four novel mutant proteins and of the R141H mutant protein in an E coli expression system. The T226S, C9Y, L32R, and C241S mutant proteins have decreased specific activity (23 to 41% of normal), are all more or less thermolabile, and R141H has no detectable activity. Our results indicate that the new mutations identified here are less severe than the inactive R141H mutant protein, conferring residual PMM activity compatible with life.


Keywords: CDG; phosphomannomutase; PMM2 mutations     

Human herpes virus 8‐unrelated primary effusion lymphoma‐like lymphoma: report of a rare case and review of the literature

Primary effusion lymphoma (PEL) is a very rare type of lymphoma usually confined to the body cavities predominantly in immunosupressed patients infected with human herpes virus 8 (HHV‐8). The new term for HHV‐8 independent PEL is HHV8‐unrelated PEL‐like lymphoma. We describe an 89‐year‐old human immunodeficiency virus (HIV)‐negative male patient with HHV8‐unrelated PEL‐like lymphoma in the pleura. No hepatosplenomegaly or lymphadenopathy was detected. Chest radiography and computed tomography revealed right pleural effusion, but no evidence of tumor mass or lymph node enlargement. Cytological analysis of the pleural effusion revealed a high‐grade lymphoma with round nuclei, prominent nucleoli and abundant cytoplasm with immunophenotypes positive for CD45, CD30, CD38, CD7 and CD71. Because of the advanced age, no chemotherapy was given. Effusion resolved spontaneously. One year after the diagnosis, a new pleural effusion developed at the left side. Following thoracentesis and pleurodesis, the patient remained in complete remission for 40 months. To date, 30 cases of HHV8‐unrelated PEL‐like lymphoma/HIV negative have been reported in the literature. The outcome of the HHV8‐unrelated PEL‐like lymphoma patients who were HIV negative seems to be better than HIV‐ and HHV‐8‐positive PEL.     

PIGW‐related glycosylphosphatidylinositol deficiency: Description of a new patient and review of the literature

Inherited glycosylphosphatidylinositol (GPI) deficiencies are a group of clinically and genetically heterogeneous conditions belonging to the congenital disorders of glycosylation. PIGW is involved in GPI biosynthesis and modification, and biallelic pathogenic variants in this gene cause autosomal recessive GPI biosynthesis defect 11. Only five patients and two fetuses have been reported in the literature thus far. Here we describe a new patient with a novel homozygous missense variant in PIGW, who presented with hypotonia, severe intellectual disability, early‐onset epileptic seizures, brain abnormalities, nystagmus, hand stereotypies, recurrent respiratory infections, distinctive facial features, and hyperphosphatasia. Our report expands the phenotype of GPI biosynthesis defect 11 to include stereotypies and recurrent respiratory infections. A detailed and long‐term analysis of the electroclinical characteristics and review of the literature suggest that early‐onset epileptic seizures are a key manifestation of GPI biosynthesis defect 11. West syndrome and focal‐onset epileptic seizures are the most common seizure types, and the fronto‐temporal regions may be the most frequently involved areas in these patients.     

X-连锁严重联合免疫缺陷病一家系分析并文献复习

目的总结分析严重联合免疫缺陷病（SCID）的临床表现、诊断方法和治疗。方法对1例生后2个月内起病,严重感染,使用抗生素治疗效果不佳,生后5个月病死,常规实验室检查外周血淋巴细胞绝对计数减少,WBC总数2.8×10^9·L^-1,L1.9×10^9·L^-1的患儿,使用流式细胞仪检测患儿及其双亲的外周血淋巴细胞表达,并抽提出DNA,对IL-2受体γ链（IL2RG）进行基因分析。外周血淋巴细胞转化试验检测患儿舅舅淋巴细胞增殖能力。回顾分析患儿家族史,通过问诊进行初步家系调查。结果流式细胞仪检测患儿外周血CD3^＋T细胞为0;NK细胞（CD16^＋CD56^＋）为4%。患儿X染色体q13.1的IL2RG基因的第6个外显子存在突变,突变位为849位碱基G缺失导致阅读框架移位,氨基酸序列位于278半胱氨酸处,并在293位产生“TGA”的终止密码子。患儿母亲被证实为携带者,但不是单纯的杂合子,可能存在嵌合突变。患儿被诊断为X-连锁严重联合免疫缺陷病（X-SCID）。患儿的舅舅生后因严重感染治疗无效而病死,其淋巴细胞转化试验植物血凝素（PHA）刺激72h,外周血单个核细胞无增殖反应（CPM值为0）。病程中使用未经特殊处理的血制品后出现高热、皮疹和肝、脾肿大后病死。回顾分析家族史,患儿母系中近3代出生男性4例均因严重感染而在婴幼儿期夭折,考虑可能也是X-SCID,女性均健康。患儿妹妹经基因分析证实亦为携带者,为IL2RG基因的第6个外显子849位碱基嵌合型。患儿的舅舅使用未经特殊处理的血制品出现的临床表现为移植物抗宿主病可能。结论经基因分析确诊了1例X-SCID,通过初步家系调查,基因分析证实患儿母亲及妹妹均为嵌合型携带者。临床上对出生后6个月内严重感染,治疗效果不佳者应警惕SCID的可能,并应进行免疫功能评价。如果疑为SCID患儿则不能接种活疫苗和使用未经特殊处理的血制品。早期?     

Expanding the clinical spectrum of mitochondrial 3‐hydroxy‐3‐methylglutaryl‐CoA synthase deficiency with Turkish cases harboring novel HMGCS2 gene mutations and literature review

Mitochondrial 3‐hydroxy‐3‐methylglutaryl‐CoA synthase (mHS) deficiency is a very rare autosomal recessive inborn error of ketone body synthesis and presents with hypoketotic hypoglycemia, metabolic acidosis, lethargy, encephalopathy, and hepatomegaly with fatty liver precipitated by catabolic stress. We report acute presentation of two patients from unrelated two families with novel homozygous c.862C>T and c.725‐2A>C mutations, respectively, in HMGCS2 gene. Affected patients had severe hypoketotic hypoglycemia, lethargy, encephalopathy, severe metabolic and lactic acidosis and hepatomegaly after infections. Surprisingly, molecular screening of the second family showed more affected patients without clinical findings. These cases expand the clinic spectrum of this extremely rare disease.     

CTLA-4 gene mutation and multiple sclerosis: A case report and literature review

We reported a patient with autoimmunity (multiple sclerosis), immunodeficiency (hypogammaglobulinemia with severe infections), enteropathy (diarrhea with intestinal inflammation), splenomegaly, lymphadenopathy and lymphocytic infiltration of non-lymphoid organs (lung, gut and brain). The patient was found to have a heterozygous mutation in cytotoxic T lymphocyte antigen-4, and had excellent response to abatacept.     

Epilepsy and movement disorders in CDG: Report on the oldest‐known MOGS‐CDG patient

Congenital glycosylation disorders (CDG) are inherited metabolic diseases due to defective glycoprotein and glycolipid glycan assembly and attachment. MOGS‐CDG is a rare disorder with seven patients from five families reported worldwide. We report on a 19‐year‐old girl with MOGS‐CDG. At birth she presented facial dysmorphism, marked hypotonia, and drug‐resistant tonic seizures. In the following months, her motility was strongly limited by dystonia, with forced posture of the head and of both hands. She showed a peculiar hyperkinetic movement disorder with a rhythmic and repetitive pattern repeatedly documented on EEG‐polygraphy recordings. Brain MRI showed progressive cortical and subcortical atrophy. Epileptic spasms appeared in first months and ceased by the age of 7 years, while tonic seizures were still present at last assessment (19 years). We report the oldest‐known MOGS‐CDG patient and broaden the neurological phenotype of this CDG.     

Paraganglioma‐like medullary thyroid carcinoma: A case report and literature review

Medullary thyroid carcinoma (MTC) accounts for 3%‐5% of all thyroid malignancies. Most MTC can be diagnosed by their typical cytologic and histologic morphology and immunohistochemical features. However, some rare variants of MTC may pose diagnostic difficulties on both cytology and histology. Paraganglioma‐like MTC (PLMTC) is a rare, but widely recognized variant of MTC. PLMTC is known to share morphological and architectural similarities with paraganglioma, hyalinizing trabecular tumor, and carcinomas of thyroid follicular cell origin, such as follicular carcinoma and follicular variant of papillary thyroid carcinoma. The combination of clinicopathologic features and a battery of immunohistochemical markers is essential for making a correct diagnosis. Herein, we report one case of PLMTC with both cytologic and histologic features and review the clinicopathologic features of previously reported cases.     

Alu‐repeat–induced deletions within the NCF2 gene causing p67‐phox–deficient chronic granulomatous disease (CGD)

Mutations that impair expression or function of the components of the phagocyte NADPH oxidase complex cause chronic granulomatous disease (CGD), which is associated with life‐threatening infections and dysregulated granulomatous inflammation. In five CGD patients from four consanguineous families of two different ethnic backgrounds, we found similar genomic homozygous deletions of 1,380 bp comprising exon 5 of NCF2, which could be traced to Alu‐mediated recombination events. cDNA sequencing showed in‐frame deletions of phase zero exon 5, which encodes one of the tandem repeat motifs in the tetratricopeptide (TPR4) domain of p67‐phox. The resulting shortened protein (p67Δ5) had a 10‐fold reduced intracellular half‐life and was unable to form a functional NADPH oxidase complex. No dominant negative inhibition of oxidase activity by p67Δ5 was observed. We conclude that Alu‐induced deletion of the TPR4 domain of p67‐phox leads to loss of function and accelerated degradation of the protein, and thus represents a new mechanism causing p67‐phox–deficient CGD. Hum Mutat 30:1–8, 2009. © 2009 Wiley‐Liss, Inc.