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Contains fulltext : 95713.pdf (Publisher’s version ) (Closed access) The core phenotype of Kleefstra syndrome (KS) is characterized by intellectual disability, childhood hypotonia, and a characteristic facial appearance. This can be caused by either submicroscopic 9q34 deletions or loss of function mutations of the EHMT1 gene. Remarkably, in three patients with a clinical suspicion of KS, molecular cytogenetic analysis revealed an interstitial 9q34 microdeletion proximal to the coding region of the EHMT1 gene based on the NM_ 024757.3 transcript. Because we found a mono-allelic EHMT1 transcript suggestive for haploinsufficiency of EHMT1 in two of these patients tested, we hypothesized that a deletion of regulatory elements or so far unknown coding sequences in the 5' region of the EHMT1 gene, might result in a phenotype compatible with KS. We further characterized the molecular content of deletions proximal to the transcript NM_ 024757.3 and confirmed presence of a novel predicted open reading frame comprising 27 coding exons (NM_ 024757.4). Further analysis showed that all three deletions included the presumed novel first exon of the EHMT1 gene. Subsequent testing of 75 individuals without previously detectable EHMT1 aberrations showed one additional case with a deletion comprising only this 5' part of the gene. These results have important implications for the genetic screening of KS and for studies of the functional significance of EHMT1.

Contains fulltext : 96044.pdf (Publisher’s version ) (Closed access) Kleefstra syndrome (KS), previously known as the 9q subtelomeric deletion syndrome (9qSTDS) is caused by haploinsufficiency of the EHMT1 gene. Both a single mutation and 9q34 microdeletions encompassing the entire gene can be responsible for this syndrome which is characterized by intellectual disability, hypotonia, and typical dysmorphisms, and may be associated with congenital heart and/or renal defects and epilepsy. Its behavioral phenotype has recently been described and comprises particular sleep disturbances and apathy. In this report, the evolution of the behavioral profile of KS is outlined by the description of three female patients aged 19, 33, and 43 years, respectively. In two patients, the syndrome was caused by an intragenic mutation and in the third by a 9q34 microdeletion encompassing the EHMT1 gene. MRI scanning of the brain in the two eldest patients demonstrated multifocal subcortical signal abnormalities. In general, the severity of the behavioral and motor deficiencies increased over time and became apparent after adolescence. It is concluded that the "regressive" phenotype of KS seems to be associated with the EHMT1 gene in particular. In addition, the utility of uncritical use of a classificatory diagnostic approach is discussed in the context of the motor and motivational disturbances that are prominent in this syndrome.

Contains fulltext : 88511.pdf (Publisher’s version ) (Closed access) The 9q Subtelomeric Deletion Syndrome (9qSTDS) is clinically characterized by mental retardation, childhood hypotonia, and facial dysmorphisms. Haploinsufficiency of the EHMT1 gene has been demonstrated to be responsible for its core phenotype. In a significant number of patients behavioral abnormalities like aggression, impulsivity, and chaotic behaviors are present as well as epileptic phenomena. Reports about the developmental, behavioral, and neuropsychiatric aspects of 9qSTDS are scarce and mostly limited to young patients only. In this report, the behavioral and neuropsychiatric characteristics of one male and one female middle-aged patient are described in whom the genetic diagnosis, interstitial and telomeric 9q deletion, respectively, was established recently. In both patients a remarkable sleep disturbance, characterized by frequent awakenings and daytime sleepiness, was present as well as a prominent apathy syndrome. The observed motor signs such as rigid flexure of the arms and finger stereotypies persisted over a period of many years and could therefore not be viewed as symptoms of catatonia. It is concluded that the proposed behavioral phenotype of 9qSTDS comprises at least an erratic sleep pattern and an enduring severe apathy.

Contains fulltext : 80656.pdf (Publisher’s version ) (Closed access) BACKGROUND: The 9q subtelomeric deletion syndrome (9qSTDS) is clinically characterised by moderate to severe mental retardation, childhood hypotonia and facial dysmorphisms. In addition, congenital heart defects, urogenital defects, epilepsy and behavioural problems are frequently observed. The syndrome can be either caused by a submicroscopic 9q34.3 deletion or by intragenic EHMT1 mutations leading to haploinsufficiency of the EHMT1 gene. So far it has not been established if and to what extent other genes in the 9q34.3 region contribute to the phenotype observed in deletion cases. This study reports the largest cohort of 9qSTDS cases so far. METHODS AND RESULTS: By a multiplex ligation dependent probe amplification (MLPA) approach, the authors identified and characterised 16 novel submicroscopic 9q deletions. Direct sequence analysis of the EHMT1 gene in 24 patients exhibiting the 9qSTD phenotype without such deletion identified six patients with an intragenic EHMT1 mutation. Five of these mutations predict a premature termination codon whereas one mutation gives rise to an amino acid substitution in a conserved domain of the protein. CONCLUSIONS: The data do not provide any evidence for phenotype-genotype correlations between size of the deletions or type of mutations and severity of clinical features. Therefore, the authors confirm the EHMT1 gene to be the major determinant of the 9qSTDS phenotype. Interestingly, five of six patients who had reached adulthood had developed severe psychiatric pathology, which may indicate that EHMT1 haploinsufficiency is associated with neurodegeneration in addition to neurodevelopmental defect.

The chromosome 9q subtelomere deletion syndrome (9qSTDS) is among the first and most common clinically recognizable syndromes to arise from widespread testing by fluorescent in situ hybridization (FISH) of subtelomere deletions. There are about 50 reported cases worldwide. Affected individuals invariably have severe hypotonia with speech and gross motor delay. The facial gestalt is distinct and features absolute or relative micro- or brachycephaly, hypertelorism, synophrys, and/or arched eyebrows, mid-face hypoplasia, a short nose with upturned nares, a protruding tongue with everted lower lip and down-turned corners of the mouth. Approximately half of affected individuals have congenital heart defects (primarily ASD or VSD). A significant minority have epilepsy and/or behavioral and sleep disturbances. A variety of other major and minor eye, ear, genital, and limb anomalies have been reported. Most patients have sub-microscopic deletions of the subtelomere region of chromosome 9q34.3 that range from400 kb to3 Mb. The 9qSTDS is caused by haplo-insufficiency of EHMT1, a gene whose protein product (Eu-HMTase1) is a histone H3 Lys 9 (H3-K9) methyltransferase. This was established by identification of three patients with features of the syndrome and either mutations or a balanced translocation in EHMT1. H3-K9 histone methylation is restricted to the euchromatin of mammals and functions to silence individual genes. Deletion size does not correlate with the severity of the 9qSTDS since patients with mutations in EHMT1 are as severely affected as those with submicroscopic deletions. Patients clinically suspected of having the 9qSTDS but with normal subtelomere deletion testing by FISH or MLPA should be considered for detailed 9q MLPA analysis and/or sequencing of EHMT1. EHMT1 is another example in the growing list of genes responsible for brain development that appear to play a role in chromatin remodeling. Published 2007 Wiley-Liss, Inc.

Case report We report a 19-year-old male with a learning disability and congenital heart defects. The patient also has mild dysmorphic facial features including facial asymmetry and mid-facial hypoplasia, high arched palate and dental crowding. Chromosomal microarray analysis demonstrated a 0.34 Mb duplication on 9q34.3, confirmed by Fluorescence in situ Hybridization (FISH). Relevance The 9q34.3 duplication we report is the smallest duplication among the cases reported thus far and includes the genes EHMT1 and NELF. The clinical manifestations in our patient were similar to those described in other reported cases of larger 9q34 duplications, implying that our small duplication encompasses a critical region for brain, cardiac and craniofacial development. We also compare our patient with its 9q34 deletion counterpart, Kleefstra syndrome, and demonstrate the overlap between the two conditions.

Deep brain stimulation (DBS) has been reported to have beneficial effects in severe, treatment-refractory cases of obsessive-compulsive disorder (OCD) and Tourette syndrome (TS). In this report, the authors present the first case in which DBS was used to treat the neuropsychiatric symptoms of Kleefstra syndrome, a rare genetic disorder characterized by childhood hypotonia, intellectual disability, distinctive facial features, and myriad psychiatric and behavioral disturbances. A 24-year-old female patient with childhood hypotonia, developmental delay, and diagnoses of autism spectrum disorder, OCD, and TS refractory to medical management underwent the placement of bilateral ventral capsule/ventral striatum (VC/VS) DBS leads, with clinical improvement. Medical providers and family observed gradual and progressive improvement in the patient's compulsive behaviors, coprolalia, speech, and social interaction. Symptoms recurred when both DBS electrodes failed because of lead fracture and dislodgement, although the clinical benefits were restored by lead replacement. The symptomatic and functional improvements observed in this case of VC/VS DBS for Kleefstra syndrome suggest a novel indication for DBS worthy of further investigation.

In a female patient with mild mental retardation an interstitial subtelomeric 9q34.3 deletion was identified by a multiplex ligation-dependent probe amplification (MLPA) based screen for subtelomeric abnormalities. Further characterization of the deletion by high-resolution tiling path array-based comparative genomic hybridization (array CGH) revealed a size of 2.2 Mb. The woman lacked the typical 9qter deletion phenotype characteristics, which is inline with the finding that both Eu-HMTase1 (EHMT) genes were present. However, she presented with mild mental retardation, some mild facial dysmorphisms and aplasia cutis. This is another example of an interstitial subtelomeric deletion, which underscores that further characterizing the precise nature of the deletion is of clinical importance. Moreover, it confirms the importance of the Eu-HMTase1 gene as the major causative factor of the classical 9qter syndrome phenotype.

Contains fulltext : 50667.pdf (Publisher’s version ) (Closed access) A clinically recognizable 9q subtelomeric deletion syndrome has recently been established. Common features seen in these patients are severe mental retardation, hypotonia, brachycephaly, flat face with hypertelorism, synophrys, anteverted nares, cupid bow or tented upper lip, everted lower lip, prognathism, macroglossia, conotruncal heart defects, and behavioral problems. The minimal critical region responsible for this 9q subtelomeric deletion (9q-) syndrome has been estimated to be

Contains fulltext : 48980.pdf (Publisher’s version ) (Closed access) BACKGROUND: A new syndrome has been recognised following thorough analysis of patients with a terminal submicroscopic subtelomeric deletion of chromosome 9q. These have in common severe mental retardation, hypotonia, brachycephaly, flat face with hypertelorism, synophrys, anteverted nares, thickened lower lip, carp mouth with macroglossia, and conotruncal heart defects. The minimum critical region responsible for this 9q subtelomeric deletion syndrome (9q-) is approximately 1.2 Mb and encompasses at least 14 genes. OBJECTIVE: To characterise the breakpoints of a de novo balanced translocation t(X;9)(p11.23;q34.3) in a mentally retarded female patient with clinical features similar to the 9q- syndrome. RESULTS: Sequence analysis of the break points showed that the translocation was fully balanced and only one gene on chromosome 9 was disrupted--Euchromatin Histone Methyl Transferase1 (Eu-HMTase1)--encoding a histone H3 lysine 9 methyltransferase (H3-K9 HMTase). This indicates that haploinsufficiency of Eu-HMTase1 is responsible for the 9q submicroscopic subtelomeric deletion syndrome. This observation was further supported by the spatio-temporal expression of the gene. Using tissue in situ hybridisation studies in mouse embryos and adult brain, Eu-HMTase1 was shown to be expressed in the developing nervous system and in specific peripheral tissues. While expression is selectively downregulated in adult brain, substantial expression is retained in the olfactory bulb, anterior/ventral lateral ventricular wall, and hippocampus and weakly in the piriform cortex. CONCLUSIONS: The expression pattern of this gene suggests a role in the CNS development and function, which is in line with the severe mental retardation and behaviour problems in patients who lack one copy of the gene.

Obesity is a symptom of diagnostic value in multiple congenital anomaly-mental retardation syndromes. While acquired non-specific weight gain related to drug intake or associated behavioural disorders occasionally occurs in the course of mental retardation, obesity is known to be a specific feature of several well defined conditions, including Bardet-Biedl syndrome, Prader-Willi syndrome, Cohen syndrome, fragile X syndrome, and several chromosomal anomalies. Yet a number of mentally retarded children with apparently early onset weight gain remain undiagnosed. Here, we report on a de novo deletion of chromosome 9q34 in two unrelated mentally retarded children with early onset obesity, distinctive facial features (brachycephaly, synophrys, anteverted nostrils, prognathism), sleep disturbances, and behavioural problems. FISH and microsatellite DNA analyses showed that the two children carried a similar small deletion (3 Mb) of the terminal long arm of chromosome 9 (del 9q34). We suggest therefore that the del 9q34 is a novel cause of syndromic obesity and mental retardation. Its association with distinctive facial features and behavioural problems should help in recognising this novel phenotype. Based on this observation, we suggest giving consideration to cryptic deletions of chromosome 9q34 in the diagnosis of unexplained obesity/mental retardation syndromes ### Case 1 A boy was born to unrelated, healthy parents after a term pregnancy and normal delivery (birth weight 3200 g, length 50 cm, OFC 34.5 cm). He was hypotonic in the first months of life but no feeding difficulties were originally noted. Excessive weight gain with increased appetite and food seeking behaviour were noted at 30 months of age. At 5 years, his weight was 26 kg (>+3 SD), length 112 cm (+1 SD), and OFC 48 cm (−2 SD) and at 9 years his weight was 72 kg (>+ 6 SD), length 144 cm (+2 SD), and OFC 52.5 cm (−0.5 SD) (figs 1A–C and 2A). Distinctive facial …

We report on a male infant with developmental delay, growth failure, hypotonia, dolichocephaly, hypoplastic midface, epicanthal folds, down-slanting palpebral fissures, foveal hypoplasia, tracheomalacia, pectus excavatum, supraventricular tachycardia, gut malrotation, hypospadias, talipes equinovarus, short third metatarsals, capillary hemangiomata, and a de novo terminal deletion at 9q34.3.

We report a case of a male infant who presented with congenital anomalies and was found to have a de novo deletion in the terminal region of the long arm of chromosome 9. He died at the age of 17 weeks of cardiorespiratory failure owing to RSV positive bronchiolitis. A review of previously published reports documented one previous report of a patient with a deletion of (9)(q34.3) and multiple congenital anomalies. Comparison with the previously reported case suggests that the phenotype observed constitutes a clinically recognisable pattern of malformations.

Introduction Over the past years several novel microdeletion syndromes have been reported that may be associated with a specific pattern of psychological dysfunctions. Two major examples are the Kleefstra syndrome (KS) and the 17q21.31 microdeletion syndrome (17qDS). KS was originally described as the 9q subtelomeric deletion syndrome associated with marked mental retardation, specific dysmorphisms, particular sleep disturbances, and progressive deterioration and apathy, suggestive for a’neurodegenerative phenotype’. Haploinsufficiency of the EHMT1 gene is proven to be the causative factor. 17qDS comprises moderate mental retardation, dysmorphisms and various congenital anomalies. It has been suggested that the behavioural phenotype includes remarkably friendly manners. The syndrome is thought to be caused by MAPT haploinsufficiency. Objectives Neuropsychological phenotyping of KS and 17qDS. Aims Assessment of neuropsychological functions of patients with either KS or 17qDS. Methods Five patients with KS and three patients with 17qDS were extensively investigated by means of broad band neurocognitive instruments as well as specific rating scales. Results The behavioural phenotype of KS was characterized by behavioural and motor deficiencies that become apparent at adolescence and increase over time. Motor symptoms could be attributed to a progressive apathy syndrome. In 17qDS the neuropsychological phenotype comprised, as compared to a matched control group, less social fear and more approaching behaviour. Conclusions In both syndromes, neuropsychological examination demonstrates specific patterns of (cognitive) development and social interaction. These findings further clarify the genotype-phenotype relation and are of importance for the establishment of an individualized behavioural and clinical management program.

IntroductionSubmicroscopic deletions of the distal long arm of chromosome 9q are relatively common and give rise to a clinically recognizable phenotype referred to as the Kleefstra Syndrome [OMIM 610253]. It was shown that haploinsufficiency of the EHMT1 (Euchromatic Histone Methyltransferase 1) gene is responsible for the core phenotype by identifying cases with intragenic EHMT1 loss of function mutations. Key features of the syndrome are mental retardation, childhood hypotonia and facial dysmorphisms. Congenital heart and renal defects, microcephaly, epilepsy, and behavioural problems are frequently present.ObjectivesDescription of the developmental, behavioural and neuropsychiatric characteristics in 4 middle aged patients with recently diagnosed Kleefstra syndromeAimsContributing to the putative behavioural phenotype of Kleefstra syndrome.MethodsDetailed neuropsychiatric and neuropsychological assessment.ResultsIn the 4 patients, conventional cytogenetic investigation showed normal karyotypes. With routine subtelomeric MLPA and additional 9q regional specific MLPA tests, a submicroscopic deletion of the long arm of chromosome 9 (9q34.3) was found. Both deletions comprised the EHMT1 gene, in agreement with the diagnosis of Kleefstra syndrome. In all patients a severe apathy and a marked dyssomnia were present. Although some motor symptoms could be assessed with a catatonia rating scale, these have to be considered as a consequence of the apathy and belong therefore not to the catatonic spectrum.ConclusionsKleefstra syndrome is constituted, in addition to its distinct phenotypic features, by a specific behavioural phenotype that comprises, apart from the absence of speech development, a specific sleep disturbance and severe apathy from the third decade on.

Contains fulltext : 110941.pdf (Publisher’s version ) (Open Access) Intellectual disability (ID) disorders are genetically and phenotypically highly heterogeneous and present a major challenge in clinical genetics and medicine. Although many genes involved in ID have been identified, the etiology is unknown in most affected individuals. Moreover, the function of most genes associated with ID remains poorly characterized. Evidence is accumulating that the control of gene transcription through epigenetic modification of chromatin structure in neurons has an important role in cognitive processes and in the etiology of ID. However, our understanding of the key molecular players and mechanisms in this process is highly fragmentary. Here, we identify a chromatin-modification module that underlies a recognizable form of ID, the Kleefstra syndrome phenotypic spectrum (KSS). In a cohort of KSS individuals without mutations in EHMT1 (the only gene known to be disrupted in KSS until now), we identified de novo mutations in four genes, MBD5, MLL3, SMARCB1, and NR1I3, all of which encode epigenetic regulators. Using Drosophila, we demonstrate that MBD5, MLL3, and NR1I3 cooperate with EHMT1, whereas SMARCB1 is known to directly interact with MLL3. We propose a highly conserved epigenetic network that underlies cognition in health and disease. This network should allow the design of strategies to treat the growing group of ID pathologies that are caused by epigenetic defects.

Background Kleefstra syndrome is characterized by intellectual disability, muscular hypotonia in childhood and typical facial features. It results from either a microdeletion of or a deleterious sequence variant in the gene euchromatic histone-lysine N-methyltransferase 1 (EHMT1) on chromosome 9q34.

Background Kleefstra syndrome is characterized by intellectual disability, muscular hypotonia in childhood and typical facial features. It results from either a microdeletion of or a deleterious sequence variant in the gene euchromatic histone-lysine N-methyltransferase 1 (EHMT1) on chromosome 9q34. Results We report on a 3-year-old girl with characteristic symptoms of Kleefstra syndrome. Array comparative genomic hybridization analysis revealed a 145 kilobases duplication spanning exons 2 to 10 of EHMT1. Sequence analysis characterized it as an intragenic tandem duplication leading to a frame shift with a premature stop codon in EHMT1. Conclusions This is the first description of an intragenic duplication of EHMT1 resulting in Kleefstra syndrome. peerReviewed

Background Kleefstra syndrome is a rare genetic disorder, with core phenotypic features encompassing developmental delay/intellectual disability, characteristic facial features – brachy(micro)cephaly, unusual shaped eyebrows, flat face with hypertelorism, short nose with anteverted nostrils, thickened lower lip, carpmouth with macroglossia - and childhood hypotonia. Some additional symptoms are observed in different percentage of the patients. Epilepsy is common symptom as well. The underlying cause of the syndrome is a submicroscopic deletion in the chromosomal region 9q34.3 or disruption of the euchromatin histone methyl transferase 1. Case presentation We describe two Hungarian Kleefstra syndrome patients, one with the classic phenotype of the syndrome, the diagnosis was confirmed by subtelomeric FISH. Meanwhile in our second patient beside the classic phenotype a new symptom – abnormal antiepileptic drug metabolic response – could be observed. Subtelomere FISH confirmed the 9q34.3 terminal deletion. Because of the abnormal drug metabolism in our second patient, we performed array CGH analysis as well searching for other rearrangements. Array CGH analysis indicated a large – 1.211 Mb -, deletion only in the 9q subtelomeric region with breakpoints ch9:139,641,471-140,852,911. Conclusions This is the first report on Kleefstra syndrome in patients describing a classical and a complex phenotype involving altered drug metabolism.