Browsing by Author "Shoukier, Moneef"

Interstitial deletions of the proximal chromosome 16q are rare. To date, only six cases with molecularly well-characterized microdeletions within this chromosomal region have been described. We report on a patient with severe psychomotor delay, dysmorphic features, microcephaly and hypoplasia of the corpus callosum, epilepsy, a heart defect, and pronounced muscular hypotonia. Array comparative genomic hybridization (aCGH) revealed that the patient's features were likely caused by a 4.7 Mb de novo deletion on chromosome 16q12.1q12.2, which was confirmed by quantitative real-time PCR (qPCR). The psychomotor delay and craniofacial dysmorphism are more severe in our patient than previously reported patients. Unmasked recessive mutations in the ZNF423 and FTO genes on the remaining allele were excluded as the putative cause for this severe phenotype. In conclusion, the phenotypic spectrum of microdeletions in 16q12 is broad and comprises variable degrees of psychomotor delay and intellectual disability, craniofacial anomalies, and additional features, including heart defects, brain malformations, and limb anomalies. (C) 2011 Wiley Periodicals, Inc.

An increasing number of patients with 3p proximal deletions were reported in the previous decade, but the region responsible for the main features such as intellectual disability (ID) and developmental delay is not yet characterized. Here we report on two monozygotic twin brothers of 2 10/12 years and an 18-year-old man, all three of them displaying severe ID, psychomotoric delay, autistic features, and only mild facial dysmorphisms. Array CGH (aCGH), revealed a 6.55Mb de novo interstitial deletion of 3p14.1p14.3 in the twin brothers and a 4.76Mb interstitial deletion of 3p14.1p14.2 in the 18-year-old patient, respectively. We compared the malformation spectrum with previous molecularly well-defined patients in the literature and in the DECIPHER database (Database of Chromosomal Imbalance and Phenotype in Humans using Ensembl Resources; http://decipher.sanger.ac.uk/). In conclusion, the deletion of a region containing 3p14.2 seems to be associated with a relative concise phenotype including ID and developmental delay. Thus, we hypothesize that 3p14.2 is the potential core region in 3p proximal deletions. The knowledge of this potential core region could be helpful in the genetic counselling of patients with 3p proximal deletions, especially concerning their phenotype. (c) 2013 Wiley Periodicals, Inc.

Here, we report a 3-year-old boy with short stature, developmental delay and mild facial dysmorphic signs. Karyotype analysis and array-CGH revealed a pure duplication 5q22.1q23.2 with a length of 14.25 Mb. As demonstrated by multicolor-fluorescence in situ hybridization, the duplicated segment was orientated in an inverted tandem manner. One of the 2 older half-brothers of the index patient was intellectually disabled and showed short stature as well. The mother of the siblings was only 149 cm in height. The affected half-brother as well as the mother of the siblings were tested positive for the same duplication. Duplications of the long arm of chromosome 5 are rare. There are 16 reported cases of different 5q segments with a pure duplication and no additional chromosomal imbalance. In order to refine the 5q-duplication phenotype, reported cases were recently classified in 3 groups on the basis of clinical findings and the involved chromosome segments. However, our case does not fit in any of these groups but is placed in the interjacent chromosomal area between 2 of these groups. Overall, this is the second reported family with a duplication of 5q22.1q23.2 and both families share phenotypic features like short stature, facial dysmorphic signs and speech delay. The reported family provides further information for delineating phenotype-genotype correlations of pure duplications of the 5q region. Copyright (C) 2012 S. Karger AG, Basel

Hereditary haemorrhagic telangiectasia (HHT), associated with arteriovenous malformations, is a genetic disease of the vascular system with a frequency of approx. 1:10,000. Genetic diagnosis serves to identify individuals at risk of developing the disease and is a useful tool for genetic counselling purposes. Questions under study: Here we report on a child presenting severe arteriovenous malformations leading to heart failure. Her mother and grandmother present fewer symptoms of hereditary haemorrhagic telangiectasia. In this study we identify the cause of HHT in the family. Methods: Clinical examination, PCR, DNA sequencing, quantitative PCR, Southern blot, x-ray, ultrasound, cardiac catheterisation and angiocardiography. Results: Initially the sequence variant in c.392C > T in the endoglin gene was detected in the grandmother, but not in other affected family members. Further analyses revealed a deletion of exon 1 of endoglin, segregating with the phenotype. Conclusions: This report points out the need for careful evaluation of molecular genetic findings, particularly in diseases with highly variable phenotype.

Background: The brain-derived neurotrophic factor (BDNF) gene is involved in mechanisms of synaptic plasticity in the brain and has been demonstrated to also play a role in influencing brain plasticity induced by transcranial magnetic and electrical stimulation. Objective and methods: This is an update of a previous study from our laboratory. We retrospectively analysed the data of 115 healthy subjects participating in 130 experimental sessions, measuring the amplitude of motor evoked potentials (MEPs) before and after transcranial stimulation of the primary motor cortex (M1). We explored whether BDNF polymorphism shapes the effects of excitatory theta burst stimulation (iTBS, n=23), anodal (n=32) and cathodal (n=19) transcranial direct current (tDCS), random noise (tRNS, n=33) and alternating current (tACS, n=13) stimulation. Results: Although a trend toward altered plasticity was observed in Val- 66Met allele carriers to stimulation with regard to all protocols compared with the response of Val66Val individuals, no significant GENOTYPE x TIME interaction was found. Conclusions: The BDNF polymorphism is suggested to have an impact on transcranial stimulation-induced plasticity in humans, which differs according to the mechanism of plasticity induction. However, according to our data, we suggest that genotyping in general, in transcranial stimulation studies including small number of subjects and at least when the M1 is stimulated, is not necessary. Nevertheless, the impact of BDNF on plasticity inducing protocols might be taken into account for e.g. in cognitive studies, when the prefrontal cortex is stimulated.

Background The brain-derived neurotrophic factor (BDNF) gene is involved in mechanisms of synaptic plasticity in the adult brain. It has been demonstrated that BDNF also plays a significant role in shaping externally induced human brain plasticity. Plasticity induced in the human motor cortex by intermittent theta-burst stimulation (iTBS) was impaired in individuals expressing the Va166Met polymorphism. Methods To explore whether this polymorphism is also important for other neuroplasticity-inducing tools in humans with modes of action differing from that of iTBS, namely, transcranial direct current (tDCS) and random noise stimulation (tRNS), we retrospectively analyzed the data of 64 subjects studied in our laboratory with regard to BDNF genotype. Results Fifteen subjects with the Va166Met allele, 46 subjects with the Val66Val allele, and 3 Met66Met carriers were identified. The response of the Va166Met allele carriers to stimulation differed in two protocols compared with the response of Val66Val individuals. For iTBS (15 subjects, 5 heterozygotes), plasticity could be only induced in the Val66Val allele carriers. However, for facilitatory tDCS (24 subjects, 10 heterozygotes), as well as for inhibitory tDCS, (19 subjects, 8 heterozygotes), carriers of the Val66-Met allele displayed enhanced plasticity, whereas for transcranial random noise stimulation (29 subjects, 8 heterozygotes), the difference between groups was not so pronounced. Conclusions BDNF polymorphism has a definite impact on plasticity in humans, which might differ according to the mechanism of plasticity induction. This impact of BDNF on plasticity should be taken into account for future studies, as well as having wider ranging implications for the treatment of neuropsychiatric disorders with transcranial stimulation tools, as it may predetermine their efficacy for the treatment of disease and rehabilitation. (C) 2010 Elsevier Inc. All rights reserved.

Branchio-oto-renal (BOR) syndrome is an autosomal dominantly inherited developmental disorder, which is characterized by anomalies of the ears, the branchial arches and the kidneys. It is caused by mutations in the genes EYA1, SIX1 and SIX5. Genomic rearrangements of chromosome 8 affecting the EYA1 gene have also been described. Owing to this fact, methods for the identification of abnormal copy numbers such as multiplex ligation-dependent probe amplification (MLPA) have been introduced as routine laboratory techniques for molecular diagnostics of BOR syndrome. The advantages of these techniques are clear compared to standard cytogenetic and array approaches as well as Southern blot. MLPA detects deletions or duplications of a part or the entire gene of interest, but not balanced structural aberrations such as inversions and translocations. Consequently, disruption of a gene by a genomic rearrangement may escape detection by a molecular genetic analysis, although this gene interruption results in haploinsufficiency and, therefore, causes the disease. In a patient with clinical features of BOR syndrome, such as hearing loss, preauricular fistulas and facial dysmorphisms, but no renal anomalies, neither sequencing of the 3 genes linked to BOR syndrome nor array comparative genomic hybridization and MLPA were able to uncover a causative mutation. By routine cytogenetic analysis, we finally identified a pericentric inversion of chromosome 8 in the affected female. High-resolution multicolor banding confirmed the chromosome 8 inversion and narrowed down the karyotype to 46,XX,inv(8)(p22q13). By applying fluorescence in situ hybridization, we narrowed down both breakpoints on chromosome 8 and found the EYA1 gene in q13.3 to be directly disrupted. We conclude that standard karyotyping should not be neglected in the genetic diagnostics of BOR syndrome or other Mendelian disorders, particularly when molecular testing failed to detect any causative alteration in patients with a convincing phenotype. (C) 2013 S. Karger AG, Basel

Using quantitative real-time polymerase chain reaction (QRT-PCR), molecular genetic analysis was carried out for endoglin (ENG) and activin A receptor type II-like kinase 1 (ACVRL1/ALK1) gene rearrangements in a group of 45 clinically confirmed hereditary haemorrhagic telangiectasia (HHT) families with negative direct sequencing results. We detected five large novel deletions, four in the ALK1 gene and one in the ENG gene. In two families, the whole ALK1 gene was deleted. One of these two deletions spanned at least 216 kb and included five neighbouring genes (LOC728503, ANKRD33, ACVR1B, GRASP, and NR4A1). The lack of additional symptoms in the patient carrying this large deletion indicates that heterozygous loss of these five genes has no obvious phenotypical effect. To our knowledge, this is the first report on whole ALK1 gene deletions in HHT patients. We rescreened our 45 families for large rearrangements using the multiplex ligation-dependent probe amplification (MLPA) method. No discrepancies between the results of QRT-PCR and MLPA were found. Our present work proves QRT-PCR as a reliable and sensitive method. Thus, our study supports that screening for large rearrangements should be considered to improve the genetic analysis in HHT patients with no apparent mutations in ALK1 and ENG using direct sequencing.

We report on monochorionic diamniotic male twins discordant for the trisomy 12p syndrome. Trisomy 12p mosaicism with a supernumerary der(12)(pter > q12) was detected in approximately 50% of lymphocytes in both children. Fluorescence in situ hybridisation (FISH) revealed a high grade mosaicism of approximately 77% trisomy 12p cells in buccal smear and 85% in hair follicles in the affected twin, while in the normal developing brother an additional 12p chromosome fragment could not be detected in those tissues. Instead, in 3% of buccal smear and hair follicle cells a minute supernumerary marker chromosome comprising central portions of chromosome 12 was observed. Trisomy 12p mosaicism, confined to the lymphocytes of the unaffected twin, may be due to prenatal twin-to-twin transfusion, explaining the conspicuously discordant clinical phenotype. We discuss the possible sequence of events leading to the cytogenetic findings and compare the clinical phenotype presented in the affected twin with other cases of trisomy 12p and tetrasomy 12p (Pallister-Killian syndrome). (c) 2012 Elsevier Masson SAS. All rights reserved.

Background: Mutations in the SPG4/SPAST gene are the most common cause for hereditary spastic paraplegia (HSP). The splice-site mutations make a significant contribution to HSP and account for 17.4% of all types of mutations and 30.8% of point mutations in the SPAST gene. However, only few studies with limited molecular approach were conducted to investigate and decipher the role of SPAST splice-site mutations in HSP. Methods: A reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and quantitative allele-specific expression assay were performed. Results: We have characterized the consequence of two novel splice-site mutations (c.1493 + 1G > A and c.1414-1G > A) in the SPAST gene in two different families with pure HSP. The RT-PCR analysis revealed that both spastin mutations are indeed splice-site mutations and cause skipping of exon 12. Furthermore, RT-PCR data suggested that these splice-site mutations may cause leaky splicing. By means of a quantitative allele-specific expression assay, we could confirm that both splice-site mutations cause leaky splicing, as the relative expression of the exon 12-skipped transcript was reduced (21.1 +/- 3.6 compared to expected 50%). Conclusions: Our finding supports a "threshold-effect-model" for functional spastin in HSP. A higher level (78.8 +/- 3.9%) of functional spastin than the expected ratio of 50% owing to leaky splicing might cause late age at onset of HSP. Remarkably, we could show that a quantitative allele-specific expression assay is a simple and effective tool to evaluate the role of most types of spastin splice-site mutations in HSP.

The SPAST gene encoding for spastin plays a central role in the genetically heterogeneous group of diseases termed hereditary spastic paraplegia (HSP). In this study, we attempted to expand and refine the genetic and phenotypic characteristics of SPAST associated HSP by examining a large cohort of HSP patients/families. Screening of 200 unrelated HSP cases for mutations in the SPAST gene led to detection of 57 mutations (28.5%), of which 47 were distinct and 29 were novel mutations. The distribution analysis of known SPAST mutations over the structural domains of spastin led to the identification of several regions where the mutations were clustered. Mainly, the clustering was observed in the AAA (ATPases associated with diverse cellular activities) domain; however, significant clustering was also observed in the MIT (microtubule interacting and trafficking), MTBD (microtubule-binding domain) and an N-terminal region (228-269 residues). Furthermore, we used a previously generated structural model of spastin as a framework to classify the missense mutations in the AAA domain from the HSP patients into different structural/functional groups. Our data also suggest a tentative genotype-phenotype correlation and indicate that the missense mutations could cause an earlier onset of the disease.

Alterations of the Fragile Mental Retardation 2 gene (FMR2, synonym AFF2) can result in non-specific, mild to borderline X-linked intellectual disability (XLID), and behavioral problems. The well-known molecular pathomechanism of this condition, also referred to as FRAXE, is a (CCG)(n) trinucleotide repeat expansion which leads to silencing of the FMR2 gene. However, deletions within the FMR2 gene may also be causative of the disorder. Here, we report on two brothers diagnosed with FRAXE in whom a small deletion in the FMR2 gene was detected by whole genome array comparative genomic hybridization (CGH). The deletion was also present in their clinically healthy mother and maternal uncle who was similarly affected, but not in a healthy older brother of the two patients. Our observation demonstrates that FMR2 gene deletions may contribute to the FRAXE phenotype. Therefore, we suggest that screening for FMR2 gene deletions using array CGH should be considered in patients with non-specific XLID and absent trinucleotide expansion. (C) 2011 Wiley-Liss, Inc.

An autosomal recessive form of hereditary spastic paraplegia (AR-HSP) is primarily caused by mutations in the SPG7 gene, which codes for paraplegin, a subunit of the hetero-oligomeric m-AAA protease in mitochondria. In the current study, sequencing of the SPG7 gene in the genomic DNA of 25 unrelated HSP individuals/families led to the identification of two HSP patients with compound heterozygous mutations (p.G349S/p.W583C and p.A510V/p.N739KfsX741) in the coding sequence of the SPG7 gene. We used a yeast complementation assay to evaluate the functional consequence of novel SPG7 sequence variants detected in the HSP patients. We assessed the proteolytic activity of hetero-oligomeric m-AAA proteases composed of paraplegin variant(s) and proteolytically inactive forms of AFG3L2 (AFG3L2(E575Q) or AFG3L2(K354A)) upon expression in m-AAA protease-deficient yeast cells. We demonstrate that the newly identified paraplegin variants perturb the proteolytic function of hetero-oligomeric m-AAA protease. Moreover, commonly occurring silent polymorphisms such as p.T503A and p.R688Q could be distinguished from mutations (p.G349S, p.W583C, p.A510V, and p.N739KfsX744) in our HSP cohort. The yeast complementation assay thus can serve as a reliable system to distinguish a pathogenic mutation from a silent polymorphism for any novel SPG7 sequence variant, which will facilitate the interpretation of genetic data for SPG7. Hum Mutat 31:617-621, 2010. (C) 2010 Wiley-Liss, Inc.

Background: Papillary renal cell carcinoma is a rare cancer. Some cases can be attributed to individuals with hereditary renal cell carcinomas usually consisting of the clear cell subtype. In addition, two syndromes with hereditary papillary renal cell carcinoma have been described. One is the hereditary leiomyomatosis and renal cell carcinoma, which is characterized by cutaneous and uterine leiomyomas and renal cell carcinoma mostly consisting of the papillary renal cell carcinoma type II with a worse prognosis. Case presentation: We describe a case of a 30-year-old woman with hereditary leiomyomatosis and renal cell carcinoma syndrome with extensively metastasized papillary renal cell carcinoma, primarily diagnosed in a cervical lymph node lacking leiomyomas at any site. Conclusion: Papillary renal cell carcinoma in young patients should be further investigated for a hereditary variant like the hereditary leiomyomatosis and renal cell carcinoma even if leiomyomas could not be detected. A detailed histological examination and search for mutations is essential for the survival of patients and relatives.

A 1-year-old female child suffering from nystagmus and abnormal head posture (AHP) was presented by the parents in our clinic. The family history revealed the presence of von Willebrand's disease in both parents. General examination showed a female child with light blond colored skin accompanied by black-haired parents. Physical and ophthalmic examination revealed nystagmus, AHP and oculocutaneous albinism. The molecular genetic analysis showed a mutation in the HPS-1 gene which confirmed the suspected diagnosis of Hermansky-Pudlak syndrome (HPS). Of clinical significance, patients with HPS commonly have hemorrhagic diathesis, granulomatous colitis or restrictive lung fibrosis. A detailed full medical history, ophthalmic examination as well as genetic analyses are essential in establishing the diagnosis of HPS. Treatment includes correcting refraction anomalies with spectacles or contact lenses, prescription of tinted glasses or surgical correction of the AHP. An internal medical consultation is also necessary for the management of other associated symptoms, such as hemorrhagic diathesis.

Terminal deletions of chromosome 3p26.3 confined to the CHL1 gene have previously been described in children with intellectual disability and epilepsy. Here, we report for the first time, a 3p26.3 duplication including only the CHL1 gene in an intellectually disabled girl with epilepsy. The penetrance of both deletions and duplications in 3p26.3 is reduced because all chromosomal imbalances were inherited from healthy parents. Further studies are needed to specify the pathogenic mechanism of 3p26.3 imbalances and to estimate recurrence risks in genetic counseling. However, the description of both deletions and duplications of chromosome 3p26.3 in nonsyndromic intellectual disability suggests that CHL1 is a dosage-sensitive gene with an important role for normal cognitive development.