Lethal respiratory failure and mild primary hypothyroidism in a term girl with a de novo heterozygous mutation in the TITF1/NKX2.1 gene

CONTEXT: Thyroid transcription factor 1 (TITF1/NKX2.1) is expressed in the thyroid, lung, ventral forebrain, and pituitary. In the lung, TITF1/NKX2.1 activates the expression of genes critical for lung development and function. Titf/Nkx2.1(-/-) mice have pituitary and thyroid aplasia but also impairment of pulmonary branching. Humans with heterozygous TITF1/NKX2.1 mutations present with various combinations of primary hypothyroidism, respiratory distress, and neurological disorders. OBJECTIVE: The objective of the study was to report clinical and molecular studies of the first patient with lethal neonatal respiratory distress from a novel heterozygous TITF1/NKX2.1 mutation. Participant: This girl, the first child of healthy nonconsanguineous French-Canadian parents, was born at 41 wk. Birth weight was 3,460 g and Apgar scores were normal. Soon after birth, she developed acute respiratory failure with pulmonary hypertension. At neonatal screening on the second day of life, TSH was 31 mU/liter (N <15) and total T(4) 245 nmol/liter (N = 120-350). Despite mechanical ventilation, thyroxine, surfactant, and pulmonary vasodilators, the patient died on the 40th day. RESULTS: Histopathology revealed pulmonary tissue with low alveolar counts. The thyroid was normal. Sequencing of the patient's lymphocyte DNA revealed a novel heterozygous TITF1/NKX2.1 mutation (I207F). This mutation was not found in either parent. In vitro, the mutant TITF-1 had reduced DNA binding and transactivation capacity. CONCLUSION: This is the first reported case of a heterozygous TITF1/NKX2.1 mutation leading to neonatal death from respiratory failure. The association of severe unexplained respiratory distress in a term neonate with mild primary hypothyroidism is the clue that led to the diagnosis.

Molecular and biochemical characterisation of a novel mutation in POLG associated with Alpers syndrome

Background DNA polymerase γ (POLG) is the only known mitochondrial DNA (mtDNA) polymerase. It mediates mtDNA replication and base excision repair. Mutations in the POLG gene lead to reduction of functional mtDNA (mtDNA depletion and/or deletions) and are therefore predicted to result in defective oxidative phosphorylation (OXPHOS). Many mutations map to the polymerase and exonuclease domains of the enzyme and produce a broad clinical spectrum. The most frequent mutation p.A467T is localised in the linker region between these domains. In compound heterozygote patients the p.A467T mutation has been described to be associated amongst others with fatal childhood encephalopathy. These patients have a poorer survival rate compared to homozygotes. Methods mtDNA content in various tissues (fibroblasts, muscle and liver) was quantified using quantitative PCR (qPCR). OXPHOS activities in the same tissues were assessed using spectrophotometric methods and catalytic stain of BN-PAGE. Results We characterise a novel splice site mutation in POLG found in trans with the p.A467T mutation in a 3.5 years old boy with valproic acid induced acute liver failure (Alpers-Huttenlocher syndrome). These mutations result in a tissue specific depletion of the mtDNA which correlates with the OXPHOS-activities. Conclusions mtDNA depletion can be expressed in a high tissue-specific manner and confirms the need to analyse primary tissue. Furthermore, POLG analysis optimises clinical management in the early stages of disease and reinforces the need for its evaluation before starting valproic acid treatment.

Microphthalmia in Texel sheep is associated with a missense mutation in the paired-like homeodomain 3 (PITX3) gene

Microphthalmia in sheep is an autosomal recessive inherited congenital anomaly found within the Texel breed. It is characterized by extremely small or absent eyes and affected lambs are absolutely blind. For the first time, we use a genome-wide ovine SNP array for positional cloning of a Mendelian trait in sheep. Genotyping 23 cases and 23 controls using Illumina's OvineSNP50 BeadChip allowed us to localize the causative mutation for microphthalmia to a 2.4 Mb interval on sheep chromosome 22 by association and homozygosity mapping. The PITX3 gene is located within this interval and encodes a homeodomain-containing transcription factor involved in vertebrate lens formation. An abnormal development of the lens vesicle was shown to be the primary event in ovine microphthalmia. Therefore, we considered PITX3 a positional and functional candidate gene. An ovine BAC clone was sequenced, and after full-length cDNA cloning the PITX3 gene was annotated. Here we show that the ovine microphthalmia phenotype is perfectly associated with a missense mutation (c.338G>C, p.R113P) in the evolutionary conserved homeodomain of PITX3. Selection against this candidate causative mutation can now be used to eliminate microphthalmia from Texel sheep in production systems. Furthermore, the identification of a naturally occurring PITX3 mutation offers the opportunity to use the Texel as a genetically characterized large animal model for human microphthalmia.

Epidermal growth factor receptor, phosphatidylinositol-3-kinase catalytic subunit/PTEN, and KRAS/NRAS/BRAF in primary resected esophageal adenocarcinomas: loss of PTEN is associated with worse clinical outcome

Alterations of the epidermal growth factor receptor (EGFR) can be observed in a significant subset of esophageal adenocarcinomas (EACs), and targeted therapy against EGFR may become an interesting approach for the treatment of these tumors. Mutations of KRAS, NRAS, BRAF, and phosphatidylinositol-3-kinase catalytic subunit (PIK3CA) and deregulation of PTEN expression influence the responsiveness against anti-EGFR therapy in colorectal carcinomas. We investigated the prevalence of these events in a collection of 117 primary resected EACs, correlated the findings with EGFR expression and amplification, and determined their clinicopathologic impact. KRAS mutations were detected in 4 (3%) of 117 tumors (3× G12D and 1 G12V mutation). One tumor had a PIK3CA E545K mutation. Neither NRAS nor BRAF mutations were detected. Sixteen (14%) of 117 cases were negative for PTEN expression, determined by immunohistochemistry. Loss of PTEN was observed predominantly in advanced tumor stages (P = .004). There was no association between PTEN and EGFR status. Loss of PTEN was associated with shorter overall and disease-free survival (P < .001 each) and also an independent prognostic factor in multivariate analysis (P = .015). EGFR status had no prognostic impact in this case collection. In summary, loss of PTEN can be detected in a significant subset of EAC and is associated with an aggressive phenotype. Therefore, PTEN may be useful as a prognostic biomarker. In contrast, mutations of RAS/RAF/PIK3CA appear only very rarely, if at all, in EAC. A possible predictive role of PTEN in anti-EGFR treatment warrants further investigations, whereas determination of RAS/RAF/PIK3CA mutations may only have a minor impact in this context.

Association of rs1182 polymorphism of the DYT1 gene with primary dystonia in Chinese population

The deletion mutation of glutamate codon (GAG) in the TOR1A gene is a major cause of primary generalized dystonia. Recent genetic studies suggest that the rs1182 polymorphism in the same gene may represent a risk factor for primary dystonia. However, this finding has been inconsistent. Furthermore, no data on such an association in a Chinese population have been published.

A novel mutation in the steroidogenic acute regulatory protein gene promoter leading to reduced promoter activity

We have identified a novel cytosine/thymidine polymorphism of the human steroidogenic acute regulatory (StAR) gene promoter located 3 bp downstream of the steroidogenic factor-1 (SF-1)-binding site and 9 bp upstream of the TATA box (ATTTAAG). Carriers of this mutation have a high prevalence of primary aldosteronism. In transfection experiments, basal StAR promoter activity was unaltered by the mutation in murine Y-1 cells and human H295R cells. In Y-1 cells, forskolin (25 microM, 6 h) significantly increased wild-type promoter activity to 230+/-33% (P<0.05, n=4). In contrast, forskolin increased mutated promoter activity only to 150+/-27%, with a significant 35% reduction compared to wild type (P<0.05, n=3). In H295R cells, angiotensin II (AngII; 10 nM) increased wild-type StAR promoter activity to 265+/-22% (P<0.01, n=3), while mutated StAR promoter activity in response to AngII only reached 180+/-29% of controls (P< 0.01, n=3). Gel mobility shift assays show the formation of two additional complexes with the mutated promoter: one with the transcription repressor DAX-1 and another with a yet unidentified factor, which strongly binds the SF-1 response element. Thus, this novel mutation in the human StAR promoter is critically involved in the regulation of StAR gene expression and is associated with reduced promoter activity, a finding relevant for adrenal steroid response to physiological stimulators.

DYT1 mutations amongst adult primary dystonia patients in Singapore with review of literature comparing East and West

BACKGROUND: Dystonia is a heterogenous group of movement disorders whose clinical spectrum is very wide. At least 13 different genes and gene loci have been reported. While a 3-bp deletion in the DYT1 gene is the most frequent cause of early limb-onset, generalized dystonia, it has also been found in non-generalized forms of sporadic dystonia. An 18-bp deletion in the DYT1 gene has also been reported. OBJECTIVES: We screened for the 3-bp and 18-bp deletions in the DYT1 gene among our sporadic, adult-onset primary dystonia patients in Singapore. We reviewed the literature to compare the frequency of DYT1 mutation between the East and the West. METHODS: We screened 54 patients with primary dystonia (focal: n=41; segmental: n=11; multifocal: n=1; generalized: n=1) for the deletions in the DYT1 gene. A careful review of all published literature on DYT1 screening among sporadic, non-familial, non-Ashkenazi Jewish patients was done. RESULTS: We did not detect any mutations in the exon 5 of the DYT1 gene in any of our patients. The frequency of DYT1 mutation amongst Asians (1.0%) was comparable to the West (1.56%) (p=NS). CONCLUSIONS: DYT1 mutations are uncommon amongst adult primary dystonia patients in Singapore.

DNAI1 mutations explain only 2% of primary ciliary dykinesia

BACKGROUND: Primary ciliary dyskinesia (PCD) is a rare recessive hereditary disorder characterized by dysmotility to immotility of ciliated and flagellated structures. Its main symptoms are respiratory, caused by defective ciliary beating in the epithelium of the upper airways (nose, bronchi and paranasal sinuses). Impairing the drainage of inhaled microorganisms and particles leads to recurrent infections and pulmonary complications. To date, 5 genes encoding 3 dynein protein arm subunits (DNAI1, DNAH5 and DNAH11), the kinase TXNDC3 and the X-linked RPGR have been found to be mutated in PCD. OBJECTIVES: We proposed to determine the impact of the DNAI1 gene on a cohort of unrelated PCD patients (n = 104) recruited without any phenotypic preselection. METHODS: We used denaturing high-performance liquid chromatography and sequencing to screen for mutations in the coding and splicing site sequences of the gene DNAI1. RESULTS: Three mutations were identified: a novel missense variant (p.Glu174Lys) was found in 1 patient and 2 previously reported variants were identified (p.Trp568Ser in 1 patient and IVS1+2_3insT in 3 patients). Overall, mutations on both alleles of gene DNAI1 were identified in only 2% of our clinically heterogeneous cohort of patients. CONCLUSION: We conclude that DNAI1 gene mutation is not a common cause of PCD, and that major or several additional disease gene(s) still remain to be identified before a sensitive molecular diagnostic test can be developed for PCD.

STAR splicing mutations cause the severe phenotype of lipoid congenital adrenal hyperplasia: insights from a novel splice mutation and review of reported cases

OBJECTIVE The steroidogenic acute regulatory protein (StAR) transports cholesterol to the mitochondria for steroidogenesis. Loss of StAR function causes lipoid congenital adrenal hyperplasia (LCAH) which is characterized by impaired synthesis of adrenal and gonadal steroids causing adrenal insufficiency, 46,XY disorder of sex development (DSD) and failure of pubertal development. Partial loss of StAR activity may cause adrenal insufficiency only. PATIENT A newborn girl was admitted for mild dehydration, hyponatremia, hyperkalemia and hypoglycaemia and had normal external female genitalia without hyperpigmentation. Plasma cortisol, 17OH-progesterone, DHEA-S, androstendione and aldosterone were low, while ACTH and plasma renin activity were elevated, consistent with the diagnosis of primary adrenal insufficiency. Imaging showed normal adrenals, and cytogenetics revealed a 46,XX karyotype. She was treated with fluids, hydrocortisone and fludrocortisone. DESIGN, METHODS AND RESULTS Genetic studies revealed a novel homozygous STAR mutation in the 3' acceptor splice site of intron 4, c.466-1G>A (IVS4-1G>A). To test whether this mutation would affect splicing, we performed a minigene experiment with a plasmid construct containing wild-type or mutant StAR gDNA of exons-introns 4-6 in COS-1 cells. The splicing was assessed on total RNA using RT-PCR for STAR cDNAs. The mutant STAR minigene skipped exon 5 completely and changed the reading frame. Thus, it is predicted to produce an aberrant and shorter protein (p.V156GfsX19). Computational analysis revealed that this mutant protein lacks wild-type exons 5-7 which are essential for StAR-cholesterol interaction. CONCLUSIONS STAR c.466-1A skips exon 5 and causes a dramatic change in the C-terminal sequence of the protein, which is essential for StAR-cholesterol interaction. This splicing mutation is a loss-of-function mutation explaining the severe phenotype of our patient. Thus far, all reported splicing mutations of STAR cause a severe impairment of protein function and phenotype.

Origin of Minority Drug-Resistant HIV-1 Variants in Primary HIV-1 Infection

Background. Drug-resistant human immunodeficiency virus type 1 (HIV-1) minority variants (MVs) are present in some antiretroviral therapy (ART)–naive patients. They may result from de novo mutagenesis or transmission. To date, the latter has not been proven. Methods. MVs were quantified by allele-specific polymerase chain reaction in 204 acute or recent seroconverters from the Zurich Primary HIV Infection study and 382 ART-naive, chronically infected patients. Phylogenetic analyses identified transmission clusters. Results. Three lines of evidence were observed in support of transmission of MVs. First, potential transmitters were identified for 12 of 16 acute or recent seroconverters harboring M184V MVs. These variants were also detected in plasma and/or peripheral blood mononuclear cells at the estimated time of transmission in 3 of 4 potential transmitters who experienced virological failure accompanied by the selection of the M184V mutation before transmission. Second, prevalence between MVs harboring the frequent mutation M184V and the particularly uncommon integrase mutation N155H differed highly significantly in acute or recent seroconverters (8.2% vs 0.5%; P < .001). Third, the prevalence of less-fit M184V MVs is significantly higher in acutely or recently than in chronically HIV-1–infected patients (8.2% vs 2.5%; P = .004). Conclusions. Drug-resistant HIV-1 MVs can be transmitted. To what extent the origin—transmission vs sporadic appearance—of these variants determines their impact on ART needs to be further explored.

Loss of Cdx2 Expression in Primary Tumors and Lymph Node Metastases is Specific for Mismatch Repair-Deficiency in Colorectal Cancer

Background: Approximately 20% of all colorectal cancers are hypothesized to arise from the "serrated pathway" characterized by mutation in BRAF, high-level CpG Island Methylator Phenotype, and microsatellite instability/mismatch repair (MMR)-deficiency. MMR-deficient cancers show frequent losses of Cdx2, a homeodomain transcription factor. Here, we determine the predictive value of Cdx2 expression for MMR-deficiency and investigate changes in expression between primary cancers and matched lymph node metastases. Methods: Immunohistochemistry for Cdx2, Mlh1, Msh2, Msh6, and Pms2 was performed on whole tissue sections from 201 patients with primary colorectal cancer and 59 cases of matched lymph node metastases. Receiver operating characteristic curve analysis and Area under the Curve (AUC) were investigated; association of Cdx2 with clinicopathological features and patient survival was carried out. Results: Loss of Cdx2 expression was associated with higher tumor grade (p = 0.0002), advanced pT (p = 0.0166), and perineural invasion (p = 0.0228). Cdx2 loss was an unfavorable prognostic factor in univariate (p = 0.0145) and multivariate [p = 0.0427; HR (95% CI): 0.58 (0.34-0.98)] analysis. The accuracy (AUC) for discriminating MMR-proficient and - deficient cancers was 87% [OR (95% CI): 0.96 (0.95-0.98); p < 0.0001]. Specificity and negative predictive value for MMR-deficiency was 99.1 and 96.3%. One hundred and seventy-four patients had MMR-proficient cancers, of which 60 (34.5%) showed Cdx2 loss. Cdx2 loss in metastases was related to MMR-deficiency (p < 0.0001). There was no difference in expression between primary tumors and matched metastases. Conclusion: Loss of Cdx2 is a sensitive and specific predictor of MMR-deficiency, but is not limited to these tumors, suggesting that events "upstream" of the development of microsatellite instability may impact Cdx2 expression.

Bevacizumab, Pemetrexed, and Cisplatin, or Bevacizumab and Erlotinib for Patients With Advanced Non-Small-Cell Lung Cancer Stratified by Epidermal Growth Factor Receptor Mutation: Phase II Trial SAKK19/09

Treatment allocation by epidermal growth factor receptor mutation status is a new standard in patients with metastatic nonesmall-cell lung cancer. Yet, relatively few modern chemotherapy trials were conducted in patients characterized by epidermal growth factor receptor wild type. We describe the results of a multicenter phase II trial, testing in parallel 2 novel combination therapies, predefined molecular markers, and tumor rebiopsy at progression. Objective: The goal was to demonstrate that tailored therapy, according to tumor histology and epidermal growth factor receptor (EGFR) mutation status, and the introduction of novel drug combinations in the treatment of advanced nonesmall-cell lung cancer are promising for further investigation. Methods: We conducted a multicenter phase II trial with mandatory EGFR testing and 2 strata. Patients with EGFR wild type received 4 cycles of bevacizumab, pemetrexed, and cisplatin, followed by maintenance with bevacizumab and pemetrexed until progression. Patients with EGFR mutations received bevacizumab and erlotinib until progression. Patients had computed tomography scans every 6 weeks and repeat biopsy at progression. The primary end point was progression-free survival (PFS) ≥ 35% at 6 months in stratum EGFR wild type; 77 patients were required to reach a power of 90% with an alpha of 5%. Secondary end points were median PFS, overall survival, best overall response rate (ORR), and tolerability. Further biomarkers and biopsy at progression were also evaluated. Results: A total of 77 evaluable patients with EGFR wild type received an average of 9 cycles (range, 1-25). PFS at 6 months was 45.5%, median PFS was 6.9 months, overall survival was 12.1 months, and ORR was 62%. Kirsten rat sarcoma oncogene mutations and circulating vascular endothelial growth factor negatively correlated with survival, but thymidylate synthase expression did not. A total of 20 patients with EGFR mutations received an average of 16.

VE1 immunohistochemistry predicts BRAF V600E mutation status and clinical outcome in colorectal cancer

AIM VE1 is a monoclonal antibody detecting mutant BRAFV600E protein by immunohistochemistry. Here we aim to determine the inter-observer agreement and concordance of VE1 with mutational status, investigate heterogeneity in colorectal cancers and metastases and determine the prognostic effect of VE1 in colorectal cancer patients. METHODS Concordance of VE1 with mutational status and inter-observer agreement were tested on a pilot cohort of colorectal cancers (n = 34), melanomas (n = 23) and thyroid cancers (n = 8). Two prognostic cohorts were evaluated (n = 259, Cohort 1 and n = 226, Cohort 2) by multiple-punch tissue microarrays. VE1 staining on preoperative biopsies (n = 118 patients) was compared to expression in resections. Primary tumors and metastases from 13 patients were tested for VE1 heterogeneity using a tissue microarray generated from all available blocks (n = 100 blocks). RESULTS Inter-observer agreement was 100% (kappa = 1.0). Concordance between VE1 and V600E mutation was 98.5%. Cohort 1: VE1 positivity (seen in 13.5%) was associated with older age (p = 0.0175) and MLH1 deficiency (p < 0.0001). Cohort 2: VE1 positivity (seen in 12.8%) was associated with female gender (p = 0.0016), right-sided tumor location (p < 0.0001), higher tumor grade (p < 0.0001) and mismatch repair (MMR)-deficiency (p < 0.0001). In survival analysis, MMR status and postoperative therapy were identified as possible confounding factors. Adjusting for these features, VE1 was an unfavorable prognostic factor. Preoperative biopsy staining matched resections in all cases except one. No heterogeneity was found across any primary/metastatic tumor blocks. CONCLUSION VE1 is highly concordant for V600E and homogeneously expressed suggesting staining can be analysed on resection specimens, preoperative biopsies, metastatic lesions and tissue microarrays.

A novel mutation in BCS1L associated with deafness, tubulopathy, growth retardation and microcephaly

We report a novel homozygous missense mutation in the ubiquinol-cytochrome c reductase synthesis-like (BCS1L) gene in two consanguineous Turkish families associated with deafness, Fanconi syndrome (tubulopathy), microcephaly, mental and growth retardation. All three patients presented with transitory metabolic acidosis in the neonatal period and development of persistent renal de Toni-Debré-Fanconi-type tubulopathy, with subsequent rachitis, short stature, microcephaly, sensorineural hearing impairment, mild mental retardation and liver dysfunction. The novel missense mutation c.142A>G (p.M48V) in BCS1L is located at a highly conserved region associated with sorting to the mitochondria. Biochemical analysis revealed an isolated complex III deficiency in skeletal muscle not detected in fibroblasts. Native polyacrylamide gel electrophoresis (PAGE) revealed normal super complex formation, but a shift in mobility of complex III most likely caused by the absence of the BCS1L-mediated insertion of Rieske Fe/S protein into complex III. These findings expand the phenotypic spectrum of BCS1L mutations, highlight the importance of biochemical analysis of different primary affected tissue and underline that neonatal lactic acidosis with multi-organ involvement may resolve after the newborn period with a relatively spared neurological outcome and survival into adulthood. CONCLUSION Mutation screening for BCS1L should be considered in the differential diagnosis of severe (proximal) tubulopathy in the newborn period. What is Known: • Mutations in BCS1L cause mitochondrial complex III deficiencies. • Phenotypic presentations of defective BCS1L range from Bjornstad to neonatal GRACILE syndrome. What is New: • Description of a novel homozygous mutation in BCS1L with transient neonatal acidosis and persistent de Toni-Debré-Fanconi-type tubulopathy. • The long survival of patients with phenotypic presentation of severe complex III deficiency is uncommon.