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Biomedical subjects

L C P Govaerts

Publications and source records attributed to L C P Govaerts.

6 recordsLinked to original sources
PubMed2005

Visual depth processing in Williams-Beuren syndrome.

Patients with Williams-Beuren Syndrome (WBS, also known as Williams Syndrome) show many problems in motor activities requiring visuo-motor integration, such as walking stairs. We tested to what extent these problems might be related to a deficit in the perception of visual depth or to problems in using this information in guiding movements. Monocular and binocular visual depth perception was tested in 33 patients with WBS. Furthermore, hand movements to a target were recorded in conditions with and without visual feedback of the position of the hand. The WBS group was compared to a group of control subjects. The WBS patients were able to perceive monocular depth cues that require global processing, but about 49% failed to show stereopsis. On average, patients with WBS moved their hand too far when no visual feedback on hand position was given. This was not so when they could see their hand. Patients with WBS are able to derive depth from complex spatial relationships between objects. However, they seem to be impaired in using depth information for guiding their movements when deprived of visual feedback. We conclude that the problems that WBS patients have with tasks such as descending stairs are not due to an inability to judge distance.

Adolescent↗
PubMed2004

Familial insertion (3;5)(q25.3;q22.1q31.3) with deletion or duplication of chromosome region 5q22.1-5q31.3 in ten unbalanced carriers.

We report on the clinical and cytogenetic data of a large family with an unbalanced insertion translocation (3;5)(q25.3;q22.1q31.3). Analysis of GTG-banded chromosomes demonstrated that unbalanced inheritance of a parental insertion translocation caused either a partial deletion or duplication 5q in this family. The derivative chromosomes were characterized further using microdissection and FISH with band-specific probes. The clinical picture of the proband with a partial deletion of chromosome 5 was characterized by moderate psychomotor retardation, mild facial dysmorphism, cleft palate, and single transverse crease. The family members with a partial duplication of chromosome 5 were borderline intelligent, had mild facial dysmorphism, a cardiac anomaly, and a high-pitched voice. The unbalanced carriers were compared with patients reported in the literature with a duplication or deletion of chromosome region 5q22.1 --> 5q31.3.

Chromosome Aberrations↗
PubMed2004

Saccade dysmetria in Williams-Beuren syndrome.

Numerous studies have described the poor visuo-spatial processing capacities of subjects with Williams-Beuren syndrome (WBS), a genetically based developmental disorder. Since visual perception and eye movements are closely related we hypothesized that the poor visuo-spatial processing capacities of subjects with WBS might be related to a poor saccadic control. Thereto, we recorded horizontal and vertical saccadic eye movements to targets using infrared video-oculography in 27 subjects with WBS and eight healthy controls. In the WBS group saccadic gains were highly variable, both between and within individual subjects, and they often needed more than one correction saccade to reach the target. Ten (out of a subgroup of 22) WBS subjects showed a large number of hypometric and/or hypermetric saccades, and, also a left-right asymmetry in saccadic gains was observed in WBS. We conclude that the observed impairments in saccadic control are likely to affect the proper processing of visuo-spatial information.

Adolescent↗
PubMed2003

Prenatal detection of complex chromosomal aberrations using advanced molecular cytogenetic techniques.

OBJECTIVE: This study aimed to identify a marker chromosome and characterize the short arm of a derivative chromosome 5 in a foetus with the following karyotype: mos 47,XX,del(5)(p?),+i(5)(p10)[50]/48,XX,del(5)(p?),+i(5)(p10),+mar[25]. METHOD: Amniocentesis was performed in the 26th week of pregnancy because of ultrasound abnormalities (polyhydramnion and decreased amount of gastric filling). All classic banding techniques were performed. FISH and microdissection combined with reverse painting were used to reveal the exact origin of the marker and any extra material on the deleted chromosome 5p. The parents decided to continue the pregnancy and we compared the clinical features of the child born in week 34 with data from the literature on trisomy 5p. The possible contribution of trisomy of the centromeric region of chromosome 8 and trisomy 8p23.3-->8pter to this clinical picture was evaluated. RESULTS: GTG banding showed one normal and two aberrant chromosomes 5 [del(5)(p?) and i(5)(p10)] in all the cells examined. Furthermore, a supernumerary marker chromosome was present in approximately 30% of the cells. The marker was CBG positive and positive with the pancentromere probe, but dystamicinA/DAPI negative. It did not contain NOR-positive satellites. FISH proved this marker to be derived from the centromeric region of chromosome 8. MicroFISH disclosed the aberrant chromosome 5 as der(5)t(5;8)(p10;p23.3). The parent's karyotypes were normal. The baby showed the characteristic features of trisomy 5p syndrome. She died at the age of 15 days after cardiorespiratory arrest. CONCLUSION: The karyotype was interpreted as mos 47,XX,add(5)(p10).rev ish der(5)t(5;8)(p10;p23.3),+i(5)(p10) (WCP5+,D5S23+)[50]/48,XX,add(5)(p10).rev ish der(5)t(5;8)(p10;p23.3),+i(5)(p10)(WCP5+,D5S23+),+mar.ish 8(p10q10)(D8Z2+,WCP8-)[25]. Therefore, the baby had complete trisomy 5p, with trisomy of the distal part of 8p and of the centromeric region of chromosome 8. The clinical significance of de novo marker chromosomes is a major problem in prenatal counselling. Molecular cytogenetic tools such as FISH and microFISH are indispensable for characterizing markers and determining the breakpoints more precisely in deleted chromosomes.

Adult↗
PubMed2002

Genetic risk factors in infertile men with severe oligozoospermia and azoospermia.

BACKGROUND: Male infertility due to severe oligozoospermia and azoospermia has been associated with a number of genetic risk factors. METHODS: In this study 150 men from couples requesting ICSI were investigated for genetic abnormalities, such as constitutive chromosome abnormalities, microdeletions of the Y chromosome (AZF region) and mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. RESULTS: Genetic analysis identified 16/150 (10.6%) abnormal karyotypes, 8/150 (5.3%) AZFc deletions and 14/150 (9.3%) CFTR gene mutations. An abnormal karyotype was found both in men with oligozoospermia and azoospermia: 9 men had a sex-chromosomal aneuploidy, 6 translocations were identified and one marker chromosome was found. Y chromosomal microdeletions were mainly associated with male infertility, due to testicular insufficiency. All deletions identified comprised the AZFc region, containing the Deleted in Azoospermia (DAZ) gene. CFTR gene mutations were commonly seen in men with congenital absence of the vas deferens, but also in 16% of men with azoospermia without any apparent abnormality of the vas deferens. CONCLUSIONS: A genetic abnormality was identified in 36/150 (24%) men with extreme oligozoospermia and azoospermia. Application of ICSI in these couples can result in offspring with an enhanced risk of unbalanced chromosome complement, male infertility due to the transmission of a Y-chromosomal microdeletion, and cystic fibrosis if both partners are CFTR gene mutation carriers. Genetic testing and counselling is clearly indicated for these couples before ICSI is considered.

Chromosome Aberrations↗