Identification and Characterization of a Novel Recurrent ERCC6 Variant in Patients with a Severe Form of Cockayne Syndrome B.

Cockayne syndrome (CS) is a rare disease caused by mutations in ERCC6/CSB or ERCC8/CSA. We report here the clinical, genetic, and functional analyses of three unrelated patients mutated in ERCC6/CSB with a severe phenotype. After clinical examination, two patients were investigated via next generation sequencing, targeting seventeen Nucleotide Excision Repair (NER) genes. All three patients harbored a novel, c.3156dup, homozygous mutation located in exon 18 of ERCC6/CSB that affects the C-terminal region of the protein. Sanger sequencing confirmed the mutation and the parental segregation in the three families, and Western blots showed a lack of the full-length protein. NER functional impairment was shown by reduced recovery of RNA synthesis with proficient unscheduled DNA synthesis after UV-C radiations in patient-derived fibroblasts. Despite sharing the same mutation, the clinical spectrum was heterogeneous among the three patients, and only two patients displayed clinical photosensitivity. This novel ERCC6 variant in Tunisian patients suggests a founder effect and has implications for setting-up prenatal diagnosis/genetic counselling in North Africa, where this disease is largely undiagnosed. This study reveals one of the rare cases of CS clinical heterogeneity despite the same mutation. Moreover, the occurrence of an identical homozygous mutation, which either results in clinical photosensitivity or does not, strongly suggests that this classic CS symptom relies on multiple factors.

Cardiac-Related Spinal Cord Tissue Motion at the Foramen Magnum is Increased in Patients with Type I Chiari Malformation and Decreases Postdecompression Surgery.

OBJECTIVE: Type 1 Chiari malformation (CM-I) is a craniospinal disorder historically defined by cerebellar tonsillar position greater than 3-5 mm below the foramen magnum (FM). This definition has come under question because quantitative measurements of cerebellar herniation do not always correspond with symptom severity. Researchers have proposed several additional radiographic diagnostic criteria based on dynamic motion of fluids and/or tissues. The present study objective was to determine if cardiac-related craniocaudal spinal cord tissue displacement is an accurate indicator of the presence of CM-I and if tissue displacement is altered with decompression. METHODS: A cohort of 20 symptomatic patients underwent decompression surgery. Fifteen healthy volunteers were recruited for comparison with the CM-I group. Axial phase-contrast magnetic resonance imaging (PC-MRI) measurements were collected before and after surgery at the FM with cranial-caudal velocity encoding and 20 frames per cardiac cycle with retrospective reconstruction. Spinal cord motion (SCM) at the FM was quantified based on the peak-to-peak integral of average spinal cord velocity. RESULTS: Tissue motion for the presurgical group was significantly greater than controls (P = 0.0009). Motion decreased after surgery (P = 0.058) with an effect size of -0.151 mm and a standard error of 0.066 mm. Postoperatively, no statistical difference from controls in bulk displacement at the FM was found (P = 0.200) after post hoc testing using the Tukey adjustment for multiple comparisons. CONCLUSIONS: These results support SCM measurement by PC-MRI as a possible noninvasive radiographic diagnostic for CM-I. Dynamic measurement of SCM provides unique diagnostic information about CM-I alongside static quantification of tonsillar position and other intracranial morphometrics.

Cockayne syndrome: a diffusion tensor imaging and volumetric study.

OBJECTIVE: Cockayne syndrome (CS) is a rare disorder characterized by severe brain atrophy, white matter (WM) hypomyelination and basal ganglia calcifications. This study aimed to quantify atrophy and WM abnormalities using diffusion tensor imaging (DTI) and volumetric analysis, to evaluate possible differences between CS subtypes and to determine whether DTI findings may correspond to a hypomyelinating disorder. METHODS: 14 patients with CS and 14 controls underwent brain MRI including DTI and a volumetric three-dimensional T1 weighted sequence. DTI analysis was made through regions of interest within the whole brain to obtain fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values and in the left centrum semiovale to obtain DTI eigenvalues. The Student's t-test was used to compare patients and controls, and CS subtypes. Given the small number of patients with CS, they were pooled into two groups: moderate (CS1/CS3) and severe (CS2/cerebro-oculo-facio-skeletal syndrome). RESULTS: Total brain volume in CS was reduced by 57%, predominantly in the infratentorial area (68%) (p < 0.001). Total brain volume reduction was greater in the severe group, but there was no difference in the degree of infratentorial atrophy in the two groups (p = 0.7). Mean FA values were lower, whereas ADC was higher in most of the WM in patients with CS (p < 0.05). ADC in the splenium of the corpus callosum and the posterior limb of the internal capsule and FA in the cerebral peduncles were significantly different between the two groups (p < 0.05). Mean ADC values corresponded to a hypomyelinating disorder. All DTI eigenvalues were higher in patients with CS, mainly for transverse diffusivity (+51%) (p < 0.001). CONCLUSION: DTI and volumetric analysis provide quantitative information for the characterization of CS and may be particularly useful for evaluating therapeutic intervention. Advances in knowledge: DTI combined with volumetric analysis provides additional information useful for not only the characterization of CS and distinction of clinical subtypes but also monitoring of therapeutic interventions.

Identification of two missense mutations of ERCC6 in three Chinese sisters with Cockayne syndrome by whole exome sequencing.

Cockayne syndrome (CS) is a rare autosomal recessive disorder, the primary manifestations of which are poor growth and neurologic abnormality. Mutations of the ERCC6 and ERCC8 genes are the predominant cause of Cockayne syndrome, and the ERCC6 gene mutation is present in approximately 65% of cases. The present report describes a case of Cockayne syndrome in a Chinese family, with the patients carrying two missense mutations (c.1595A>G, p.Asp532Gly and c.1607T>G, p.Leu536Trp) in the ERCC6 gene in an apparently compound heterozygote status, especially, p.Asp532Gly has never been reported. The compound heterozygote mutation was found in three patients in the family using whole exome sequencing. The patients' father and mother carried a heterozygous allele at different locations of the ERCC6 gene, which was confirmed by Sanger DNA sequencing. The two mutations are both located in the highly conserved motif I of ATP-binding helicase and are considered "Damaging," "Probably Damaging," "Disease Causing," and "Conserved", indicating the role of DNA damage in the pathogenetic process of the disease. The results not only enrich the ERCC6 mutations database, but also indicate that whole exome sequencing will be a powerful tool for discovering the disease causing mutations in clinical diagnosis.

Atypical progeroid syndrome due to heterozygous missense LMNA mutations.

CONTEXT: Hutchinson-Gilford progeria syndrome (HGPS) and mandibuloacral dysplasia are well-recognized allelic autosomal dominant and recessive progeroid disorders, respectively, due to mutations in lamin A/C (LMNA) gene. Heterozygous LMNA mutations have also been reported in a small number of patients with a less well-characterized atypical progeroid syndrome (APS). OBJECTIVE: The objective of the study was to investigate the underlying genetic and molecular basis of the phenotype of patients presenting with APS. RESULTS: We report 11 patients with APS from nine families, many with novel heterozygous missense LMNA mutations, such as, P4R, E111K, D136H, E159K, and C588R. These and previously reported patients now reveal a spectrum of clinical features including progeroid manifestations such as short stature, beaked nose, premature graying, partial alopecia, high-pitched voice, skin atrophy over the hands and feet, partial and generalized lipodystrophy with metabolic complications, and skeletal anomalies such as mandibular hypoplasia and mild acroosteolysis. Skin fibroblasts from these patients when assessed for lamin A/C expression using epifluorescence microscopy revealed variable nuclear morphological abnormalities similar to those observed in patients with HGPS. However, these nuclear abnormalities in APS patients could not be rescued with 48 h treatment with farnesyl transferase inhibitors, geranylgeranyl transferase inhibitors or trichostatin-A, a histone deacetylase inhibitor. Immunoblots of cell lysates from fibroblasts did not reveal prelamin A accumulation in any of these patients. CONCLUSIONS: APS patients have a few overlapping but some distinct clinical features as compared with HGPS and mandibuloacral dysplasia. The pathogenesis of clinical manifestations in APS patients seems not to be related to accumulation of mutant farnesylated prelamin A.

MR findings of cerebral white matter in Cockayne syndrome.

The characteristic magnetic resonance (MR) findings of Cockayne syndrome have been reported; however, the corresponding characteristics on diffusion-weighted and fluid-attenuated inversion recovery (FLAIR) imaging are yet to be documented. In this adult case with Cockayne syndrome, we identified small patchy subcortical lesions visualized as areas of high intensity on diffusion-weighted images and low intensity on FLAIR images. It is possible that these findings reflect active demyelinating lesions.

Cockayne syndrome: the developing phenotype.

Cockayne syndrome is a rare autosomal recessive condition comprising microcephaly, "cachectic dwarfism" and progressive neurological degeneration. We present a 21-year-old woman who was not diagnosed with Cockayne syndrome type I until she was 21 years old. Family photographs demonstrated that the phenotype of Cockayne syndrome did not become evident until she was 8 years old. She had severe microcephaly, micrognathia, protruding ears, dental overcrowding with caries, progressive spastic quadriparesis, and severe developmental regression. Her head computed tomography (CT) showed bilateral calcification of the globus pallidus and global atrophy. The purpose of this clinical report is to alert clinicians to the fact that the phenotypic features of Cockayne syndrome may be very subtle early in the course of the disease.

Nondetectable cone and rod electroretinographic responses in a patient with Cockayne syndrome.

A 10-year-old girl complained or poor vision in both eyes. The patient showed progeria, physical and mental retardation, sensorineural hearing loss, cutaneous photosensitivity, hyperopia, poor pupillary dilation, exotropia, salt-and-pepper fundi, nondetectable cone and rod electroretinographic (ERG) responses, cerebral atrophy on computed tomography, and demyelination of periventricular white matter on magnetic resonance imaging. We believe that nondetectable cone and rod ERG responses in Cockayne syndrome, as demonstrated in our patient, may be uncommon.

MRI in the diagnosis of Cockayne's syndrome. One case.

Computerized tomography (CT) and magnetic resonance imaging (RMI) showed cortico-subcortical atrophy as well as calcification of the basal ganglia and the cerebellar dentate nuclei in a patient presenting with cerebellar syndrome. RMI was particularly useful in imaging the demyelination of the periventricular white matter and the subcortical U fibres. A diagnosis of Cockayne's syndrome was made. This is an extremely rare hereditary disease of unknown pathogenesis. Defective recovery of DNA synthesis has been suggested.

[Cockayne's syndrome presenting cerebral ischemic attack: case report].

A 29-year-old man with Cockayne's syndrome (CS), presenting reversible ischemic neurological deficit is reported. In his past history, hearing disturbance developed at 6 years old and visual disturbance at 12 years old. His parents have consanguinious marriage. He came to our hospital complaining of right-sided hemiparesis and speech disturbance. He was 115.8 cm tall and his weight 20 kg. The characteristic manifestation of CS, i. e., dwarfism, mental retardadation, cachectic feature, retinal atrophy, neural deafness and calcification of bilateral basal ganglia were all noticed. A CT scan on admission revealed marked brain atrophy as well as the intracranial calcifications, while no lesions compatible with his neurological findings were detected. Cerebral ischemic state was mostly suspected. Following up with conservative therapy by the use of fibrinolytic agent, his neurological deteriorations disappeared on the 4th hospital day. Cerebral angiograms showed stenotic lesions of both C1-C2 portion of the left internal carotid artery and the right middle cerebral artery, and the aneurysm in the right internal carotid artery. Such atherosclerotic vascular change as observed in the cerebral angiograms in this case have progressed rapidly for his age. In this case, diabetes mellitus and hyperlipoproteinemia such as increased total cholesterol, increased triglyceride, decreased HDL and increased apoprotein B and C II were complicated for the risk factor of the atherosclerosis. It's controversial that early progress of atherosclerosis is due to ideopathic original feature of CS or to the secondary change from these complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Distinctive skeletal dysplasia in Cockayne syndrome.

Cockayne syndrome is a well-known autosomal recessive form of dwarfism with senile-like appearance. Skeletal changes such as flattening of vertebral bodies, ivory epiphyses and thickening of cranial vault, have been observed in some patients with this condition. We describe here a 5.5-year-old girl with the typical clinical signs of Cockayne syndrome and a distinctive form of bone dysplasia with major involvement of the spine.

Cockayne syndrome.

The diagnosis of Cockayne syndrome was established with the aid of cranial computed tomography (CT) in a child with growth deficiency, mental retardation, and neurologic findings which are typical for this rare childhood disorder. Calcification of basal ganglia and hydrocephalus ex vacuo are neuropathologic characteristics of Cockayne syndrome which may be present on CT as early as 3 years of age.

[Cockayne syndrome. 3 cases]. / Sindrome di Cockayne. Tre casi.

Three cases of Cockayne's syndrome, observed in patients aged 10, 5 and 1 years are reported and discussed; skeletal X-ray findings are illustrated and analysed.