Publications by authors named "Frits Beemer"

The role of rare genetic variants, in particular copy number variants (CNVs), in the etiology of neurodevelopmental disorders is becoming increasingly clear. While the list of these disorder-related CNVs continues to lengthen, it has also become clear that in nearly all genetic variants the proportion of carriers who express the associated phenotype is far from 100%. To understand this variable penetrance of CNVs it is important to realize that even the largest CNVs represent only a tiny fraction of the entire genome.

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Patients with the 22q11-deletion syndrome (22q11DS) are at an increased risk of developing schizophrenia. Besides the effects of genetic variation, environmental factors could also be important in modifying the risk of schizophrenia in 22q11DS patients. In particular, previous studies have shown the importance of stress as a precipitating factor of psychosis.

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Patients with 22q11DS are at risk of behavioral problems and cognitive impairment. Recent studies suggest a possible intellectual decline in 22q11DS children. To date it is unknown if cognitive development is related to the behavioral problems in 22q11DS.

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Children with the 22q11.2 deletion syndrome (22q11DS) are at an increased risk of psychiatric problems from pre-adolescence; little is known, however, about behavioral problems at a preschool age and the relationship between speech and behavior in this group. Parents of 90 children (aged 1.

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Objective: Palatal anomalies are one of the identifying features of 22q11.2 deletion syndrome (22q11.2DS) affecting about one third of patients.

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Velo-cardio-facial syndrome/DiGeorge syndrome, also known as 22q11.2 deletion syndrome (22q11DS) is the most common microdeletion syndrome, with an estimated incidence of 1/2,000-1/4,000 live births. Approximately 9-11% of patients with this disorder have an overt cleft palate (CP), but the genetic factors responsible for CP in the 22q11DS subset are unknown.

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Background: People with 22q11.2 deletion syndrome (velo-cardio-facial syndrome) have a 30-fold risk of developing schizophrenia. In the general population the schizophrenia phenotype includes a cognitive deficit and a decline in academic performance preceding the first episode of psychosis in a subgroup of patients.

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The purpose of this study was to explore the relationship between intelligence and visual motor integration skills in 5-year-old children with 22q11-deletion syndrome (22q11DS) (N = 65, 43 females, 22 males; mean age 5.6 years (SD 0.2), range 5.

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Recent array-based studies have detected a wealth of copy number variations (CNVs) in patients with autism spectrum disorders (ASD). Since CNVs also occur in healthy individuals, their contributions to the patient's phenotype remain largely unclear. In a cohort of children with symptoms of ASD, diagnosis of the index patient using ADOS-G and ADI-R was performed, and the Social Responsiveness Scale (SRS) was administered to the index patients, both parents, and all available siblings.

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Haploinsufficiency of TBX1, encoding a T-box transcription factor, is largely responsible for the physical malformations in velo-cardio-facial /DiGeorge/22q11.2 deletion syndrome (22q11DS) patients. Cardiovascular malformations in these patients are highly variable, raising the question as to whether DNA variations in the TBX1 locus on the remaining allele of 22q11.

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This study was designed to examine morphological features in a large group of children with autism spectrum disorder versus normal controls. Amongst 421 patients and 1,007 controls, 224 matched pairs were created. Prevalence rates and odds ratios were analyzed by conditional regression analysis, McNemar test or paired t-test matched pairs.

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Article Synopsis
  • * The study analyzed 188 patients and found 77 distinct mutations in COL2A1, with specific mutations leading to notable eye issues like vitreous anomalies and retinal detachments.
  • * A scoring system was developed to help assess the likelihood of COL2A1 mutations based on symptoms like cleft palate and family history, improving diagnostic precision for Stickler syndrome type 1.
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The recent identification of copy-number variation in the human genome has opened up new avenues for the discovery of positional candidate genes underlying complex genetic disorders, especially in the field of psychiatric disease. One major challenge that remains is pinpointing the susceptibility genes in the multitude of disease-associated loci. This challenge may be tackled by reconstruction of functional gene-networks from the genes residing in these loci.

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The association between the 22q11.2 deletion syndrome (22q11DS) and psychiatric disorders, particularly psychosis, suggests a causal relationship between 22q11DS genes and abnormal brain function. The genes catechol-O-methyl-transferase (COMT) and proline dehydrogenase both reside within the commonly deleted region of 22q11.

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Article Synopsis
  • Pontocerebellar hypoplasias (PCH) are a group of serious genetic disorders that affect brain development, leading to issues like a smaller cerebellum and various cognitive and motor difficulties.
  • The study identified mutations in the tRNA-splicing endonuclease complex in two specific PCH subtypes (PCH2 and PCH4).
  • This research suggests that problems with RNA processing may play a crucial role in the development of neurological disorders.
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Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders with a strong genetic etiology. Cytogenetic abnormalities have been detected in 5-10% of the patients with autism. In this study, we present the clinical, cytogenetic and array-comparative genomic hybridization (array-CGH) evaluation of a 13-year-old male with severe developmental delay, facial dysmorphic features, autism and self mutilation.

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The 22q11.2 deletion syndrome (22q11DS) is associated with an increased prevalence (20-30%) of schizophrenia. Therefore, it is likely that one or more genes within the 22q11.

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We report on an 8(1)/(2)-year-old girl with severe pre- and postnatal growth retardation, congenital heart malformation, facial asymmetry, oculocutaneous albinism without misrouting and subluxation of the radial heads. Her intelligence was in the low normal range. By GTG-banding a deletion of band 15q26 was found.

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The Wolf-Hirschhorn syndrome (WHS (MIM 194190)), which is characterized by growth delay, mental retardation, epilepsy, facial dysmorphisms, and midline fusion defects, shows extensive phenotypic variability. Several of the proposed mutational and epigenetic mechanisms in this and other chromosomal deletion syndromes fail to explain the observed phenotypic variability. To explain the complex phenotype of a patient with WHS and features reminiscent of Wolfram syndrome (WFS (MIM 222300)), we performed extensive clinical evaluation and classical and molecular cytogenetic (GTG banding, FISH and array-CGH) and WFS1 gene mutation analyses.

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We report two sisters born to consanguineous parents with an identical syndrome consisting of severe mental retardation and epilepsy, hypoplastic terminal phalanges, and anteriorly displaced anus. Further metabolic and genetic testing failed to detect the etiology. A whole genome linkage scan showed homozygosity for a 28-Mb region on chromosome 1p, and a 65-Mb region spanning most of chromosome 14.

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Little is known about the relation between communication during cancer genetic counseling and outcome. We assessed associations between counselor-counselee communication and counselee satisfaction, cognitions, anxiety, and fulfillment of major needs, corrected for pre-visit levels as appropriate. In total 171 consecutive new counselees, mainly referred for breast or colon cancer, received pre- and post-visit questionnaires assessing needs/fulfillment, knowledge, perceived control (PPC), anxiety (STAI), and satisfaction.

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Objective: The aim of the present study was to investigate whether medical care providers in the Netherlands are adequately educated in genetics by collecting information about the current state of genetics education of non-genetics health care professionals.

Method: The curricula of the 8 universities providing medical education and of all varieties of specialised medical training were examined for the year 2002.

Results: In most universities, the number of hours spent on genetics education is small, and genetics is relatively invisible, being integrated within several courses, comprising only a small proportion of the total course (a mean of 8%).

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Objective: To examine psychopathology and influence of intelligence level on psychiatric symptoms in children with the 22q11.2 deletion syndrome (22q11DS).

Method: Sixty patients, ages 9 through 18 years, were evaluated.

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Article Synopsis
  • - Johanson-Blizzard syndrome is a genetic disorder linked to chromosome 15 and is characterized by pancreatic insufficiency, various malformations, and often cognitive impairments.
  • - Mutations in the UBR1 gene, which plays a role in protein degradation and is crucial for pancreatic health, were found in families affected by this syndrome.
  • - Research with Ubr1(-/-) mice showed that the absence of UBR1 leads to pancreatic issues and other health problems, indicating UBR1's importance in maintaining organ function through its role in the N-end rule pathway.
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