Whole exome sequencing of sporadic patients with Currarino Syndrome: A report of three trios.

Currarino Syndrome is a rare congenital malformation syndrome described as a triad of anorectal, sacral and presacral anomalies. Currarino Syndrome is reported to be both familial and sporadic. Familial CS is today known as an autosomal dominant disorder caused by mutations in the transcription factor MNX1. The aim of this study was to look for genetic causes of Currarino Syndrome in sporadic patients after ruling out other causes, like chromosome aberrations, disease-causing variants in possible MNX1 cooperating transcription factors and aberrant methylation in the promoter of the MNX1 gene. The hypothesis was that MNX1 was affected through interactions with other transcription factors or through other regulatory elements and thereby possibly leading to abnormal function of the gene. We performed whole exome sequencing with an additional 6Mb custom made region on chromosome 7 (GRCh37/hg19, chr7:153.138.664-159.138.663) to detect regulatory elements in non-coding regions around the MNX1 gene. We did not find any variants in genes of interest shared between the patients. However, after analyzing the whole exome sequencing data with Filtus, the in-house SNV filtration program, we did find some interesting variants in possibly relevant genes that could be explaining these patients` phenotypes. The most promising genes were ETV3L, ARID5A and NCAPD3. To our knowledge this is the first report of whole exome sequencing in sporadic CS patients.

Familial globotriaosylceramide-associated cardiomyopathy mimicking Fabry disease.

OBJECTIVE: To characterise a globotriaosylceramide (Gb3) storage cardiomyopathy mimicking Fabry. METHODS: We investigated five patients from two unrelated families with early adult onset unexplained left ventricular hypertrophy. Endomyocardial biopsy was performed in all patients and diagnostic kidney biopsies in two of them. We measured α-galactosidase A activity in all patients. Three patients were checked for LAMP1 or LAMP2 deficiency and screened for congenital disorders of glycosylation. Gb3 concentration was quantified in plasma, urinary sediment and cardiac muscle. We sequenced the Fabry and Danon genes and looked for other genetic causes by single-nucleotide polymorphism array haplotyping and whole exome sequencing. RESULTS: Three patients had a striking fat distribution around the buttocks and upper thighs. All patients developed bradyarrhythmias and needed pacemakers. Cardiac transplantation was performed in three patients due to end-stage heart failure, one patient died before transplantation. The cardiomyocytes contained lysosomal vacuoles with lamellar myelin-like deposits. Interstitial cells had vacuoles containing granular material. Deposits were found in the kidneys without renal dysfunction. The histological pattern was atypical for Fabry disease. Biochemical studies revealed normal activity of α-galactosidase A and other relevant enzymes. There was a selective accumulation of Gb3 in cardiomyocytes, at levels found in patients with Fabry disease, but no mutations in the Fabry gene, and Fabry disease was excluded. Other known lysosomal storage diseases were also excluded. Single-nucleotide polymorphism array haplotyping and whole exome sequencing could not identify the genetic cause. CONCLUSIONS: We describe a novel familial Gb3-associated cardiomyopathy. Autosomal recessive inheritance is likely, but the genetic and metabolic cause remains to be identified.

A 5.8 kb deletion removing the entire MNX1 gene in a Norwegian family with Currarino syndrome.

Currarino syndrome (CS) is a clinically variable disorder characterized by anorectal, sacral and presacral anomalies. It is associated with loss-of-function mutations in the motor neuron and pancreas homeobox 1 (MNX1) gene. Inheritance is autosomal dominant, expression variable and penetrance incomplete. We describe a Norwegian family with typical CS in which a heterozygous deletion removes the entire MNX1 gene but no other known genes. We also report MNX1 mutations in three other Norwegian families and confirm that the GCC12 repeat (c.373_375[12]) is a normal allelic variant. This work underscores the importance of dosage analysis of MNX1 when Sanger sequencing is negative.

Copy number variation findings among 50 children and adolescents with autism spectrum disorder.

OBJECTIVES: Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopment disorders with a complex genetic aetiology. The aim of this study was to identify copy number variations (CNVs) with a clinical significance for ASD. MATERIALS AND METHODS: Array-based comparative genomic hybridization was applied to detect CNVs in a clinically well-characterized population of 50 children and adolescents with ASD. RESULTS: Nine CNVs with predicted clinical significance were identified among eight individuals (detection rate 16%). Three of the CNVs are recurrently associated with ASDs (15q11.2q13.1) or have been identified in ASD populations [3p14.2 and t(8;12)(p23.1;p13.31)]. The remaining regions (15q11.2, 10q21.1, Xp22.2, 16p13.3 and 22q13.1) have not been reported previously as candidate genes for ASD. CONCLUSION: This study identified five novel CNVs among the individuals. The causal relationship between identified CNVs and the ASD phenotype is not fully established. However, the genes involved are associated with ASD and/or other neuropsychiatric disorders, or implicated in synaptic and neuronal activity, thus suggesting clinical significance. Further identification of ASD-associated CNVs is required, together with a broad clinical characterization of affected individuals to identify genotype-phenotype correlations.

Two new Rett syndrome families and review of the literature: expanding the knowledge of MECP2 frameshift mutations.

BACKGROUND: Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder, which is usually caused by de novo mutations in the MECP2 gene. More than 70% of the disease causing MECP2 mutations are eight recurrent C to T transitions, which almost exclusively arise on the paternally derived X chromosome. About 10% of the RTT cases have a C-terminal frameshift deletion in MECP2. Only few RTT families with a segregating MECP2 mutation, which affects female carriers with a phenotype of mental retardation or RTT, have been reported in the literature. In this study we describe two new RTT families with three and four individuals, respectively, and review the literature comparing the type of mutations and phenotypes observed in RTT families with those observed in sporadic cases. Based on these observations we also investigated origin of mutation segregation to further improve genetic counselling. METHODS: MECP2 mutations were identified by direct sequencing. XCI studies were performed using the X-linked androgen receptor (AR) locus. The parental origin of de novo MECP2 frameshift mutations was investigated using intronic SNPs. RESULTS: In both families a C-terminal frameshift mutation segregates. Clinical features of the mutation carriers vary from classical RTT to mild mental retardation. XCI profiles of the female carriers correlate to their respective geno-/phenotypes. The majority of the de novo frameshift mutations occur on the paternally derived X chromosome (7/9 cases), without a paternal age effect. CONCLUSIONS: The present study suggests a correlation between the intrafamilial phenotypic differences observed in RTT families and their respective XCI pattern in blood, in contrast to sporadic RTT cases where a similar correlation has not been demonstrated. Furthermore, we found de novo MECP2 frameshift mutations frequently to be of paternal origin, although not with the same high paternal occurrence as in sporadic cases with C to T transitions. This suggests further investigations of more families. This study emphasizes the need for thorough genetic counselling of families with a newly diagnosed RTT patient.

A novel BMPR2 gene mutation associated with exercise-induced pulmonary hypertension in septal defects.

OBJECTIVE: Our study aimed to investigate the relationship between exercise-induced pulmonary arterial hypertension and genetic changes related to the transforming growth factor-ß (TGF-ß) signalling pathway in patients with cardiac septal defects. DESIGN: In a population-based group of 44 patients (age 13-25 years) with either isolated ventricular septal defect (n=27) or isolated atrial septal defect (n=17), right ventricular systolic pressure response to submaximal exercise was studied by echocardiography and classified as normal (≤45 mmHg), borderline (45-50 mmHg) or abnormal (>50 mmHg). Three genes related to TGF-ß, bone morphogenetic protein receptor type 2 (BMPR2), activin receptor-like kinase 1 (ALK1) and endoglin (ENG), were analyzed by DNA sequencing (only BMPR2) and multiplex ligand-dependent probe amplification (BMPR2, ALK1 and ENG). RESULTS: Pressure response was borderline in five and abnormal in nine patients. Five patients showed mutations in exon 12 of the bone morphogenetic protein receptor type 2 gene. The previously described polymorphism S775N (c. 2324, G > A) was found in three patients with normal pressure response. The mutation Y589C (c. 1766, A > G), which has not been described previously, was found in two of 14 patients with borderline/abnormal pressure response. CONCLUSION: Genetic changes in the BMPR2 gene may be overrepresented in patients with cardiac septal defects and exercise-induced pulmonary hypertension.

Age-dependent clinical problems in a Norwegian national survey of patients with the 22q11.2 deletion syndrome.

Patients with the 22q11.2 deletion syndrome display a wide phenotypic variation that is important for clinical follow-up. In this national survey of 60 patients (ages 1 to 54 years) diagnosed by Fluorescence in situ hybridization test, data were collected from medical records, a physical examination, and a semistructured interview. Ultrasound investigation of the kidneys was also performed. In addition, multiplex ligation probe amplification assay was performed to detect deletion size. Phenotypic features leading to the genetic diagnosis were noted. The patients showed a variety of organ malformations including 39 with heart anomalies. Only 20 individuals had been diagnosed with 22q11.2 DS in the first year of life. Four patients had renal and five males had genital malformations. The increased infection susceptibility (excluding otitis media) and most feeding difficulties subsided during early childhood. Speech difficulties started early and were a major problem for many patients at least until 10 years of age. Ten patients developed kyphoscoliosis in late childhood. In teenagers and adults, abnormal social behavior, learning disabilities, and psychiatric symptoms dominated. Our study which also includes adult patients emphasizes a marked change in challenges in individuals with the 22q11.2 deletion syndrome with increasing age.

Cognitive impairment and the role of the ApoE epsilon4-allele after stroke--a 13 months follow-up study.

OBJECTIVE: To examine the relationship between the ApoE epsilon4 allele and cognitive impairment 13 months after stroke. METHODS: One hundred four stroke rehabilitation patients were cognitively tested on average 18 days after hospital admission and again 13 months later with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The following potential risk factors for post-stroke cognitive impairment (defined by a RBANS total index score below 77.5 points) at 13 months follow-up were analyzed in bivariate and logistic regression analyses: ApoE-genotype, socio-demographic variables, pre-stroke cognitive reduction (The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)), vascular factors, lesion characteristics, and neurological impairment (The National Institute of Health Stroke Scale (NIHSS)). Differences in general cognitive performance (pre-stroke, baseline, and follow-up) across patients with different ApoE-genotypes were analyzed, and lastly differences between epsilon4-carriers and non-carriers for changes in performance in various cognitive domains over the 13 months period were examined. RESULTS: Significant risk factors for cognitive impairment at 13 months were ApoE epsilon4, pre-stroke cognitive reduction (IQCODE 3.44+), previous stroke, and neurological impairment (NIHSS Total Score >5). A significant dose-dependent effect of the ApoE-genotype in relation to overall post-stroke cognitive functioning was found at baseline and follow-up, but not pre-stroke. The epsilon4 carriers showed a significant decline in tests related to verbal learning and memory compared to the non-carriers. CONCLUSIONS: The ApoE epsilon4-allele constitutes an independent risk factor for cognitive impairment at 13 months post-stroke, and is associated with progression of cognitive decline in tasks related to verbal learning and memory.

Association between ApoE epsilon4 and cognitive impairment after stroke.

BACKGROUND AND PURPOSE: The understanding of the contribution of genetic factors to cognitive impairment after stroke is incomplete. The aim of the study was to examine whether the apolipoprotein E epsilon4 allele (ApoE epsilon4) is a risk factor for cognitive impairment in the early phase after stroke. METHODS: The sample comprised 152 Norwegian stroke rehabilitation inpatients (mean age 76.8 years, SD 10.5) examined at a mean of 18.3 days (SD 13.4) after hospital admission. Post-stroke cognitive impairment was assessed with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The following proposed risk factors were analysed: ApoE genotype, demographics (age, sex, education), pre-stroke cognitive reduction [Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)], pre-stroke vascular factors (including previous stroke), stroke characteristics (type, location), and neurological stroke-related impairment [National Institutes of Health Stroke Scale (NIHSS)]. Cognitive impairment was defined as an RBANS total index score < or =1.5 SD below the mean. Multiple logistic regression analyses were performed to find risk factors for post-stroke cognitive impairment. RESULTS: Four variables were found to be independent risk factors for cognitive impairment after stroke: ApoE epsilon4 (OR = 3.7; 95% CI = 1.2-11.6), IQCODE score > or =3.44 (OR = 9.2; 95% = CI 2.3-37.2), total or partial anterior stroke syndromes (OR = 3.2; 95% CI = 1.3-8.0), and NIHSS total score >5 (OR = 7.3; 95% CI = 2.7-19.7). No association between ApoE epsilon4 and pre-stroke cognitive reduction (IQCODE) was found. CONCLUSIONS: The presence of one or two ApoE epsilon4 alleles may be a significant independent risk factor for cognitive impairment in the early phase after stroke.