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Biomedical subjects

C M Aalfs

Publications and source records attributed to C M Aalfs.

At least 19 recordsLinked to original sources
PubMed2005

[DNA-analysis in hereditary cancer: the importance of a reliable family history].

Three patients, a 45-year-old man, a 51-year-old woman and a 43-year-old woman, wanted to know whether they had a hereditary predisposition for cancer. The family of patient A fulfilled the clinical diagnostic criteria for hereditary non-polyposis colorectal carcinoma (HNPCC). The family of patient B fulfilled the clinical diagnostic criteria for hereditary breast/ovarian cancer (HBOC). The family of patient C did not completely fulfil the criteria for HBOC since only two family members had a confirmed diagnosis of breast cancer. In all three families, DNA-mutation analysis was performed. In families A and B no mutation was found. However, based on the family history, the diagnosis of hereditary cancer was made and recommendations for surveillance were given. After extensive counselling, one member of family B eventually decided to have prophylactic surgery performed. A few years later, a pathogenic mutation in BRCA2 was found in family B. In family C, an unclassified variant was found in BRCA1. Further investigations in the family were not possible, due to a lack of co-operation from family members. It is important to obtain a thorough and complete family history. When DNA-analysis remains inconclusive or if an unclassified variant is found, recommendations for surveillance will be based on this family history.

Adult↗
PubMed2005

Multiplicity in polyp count and extracolonic manifestations in 40 Dutch patients with MYH associated polyposis coli (MAP).

OBJECTIVE: To investigate the contribution of MYH associated polyposis coli (MAP) among polyposis families in the Netherlands, and the prevalence of colonic and extracolonic manifestations in MAP patients. METHODS: 170 patients with polyposis coli, who previously tested negative for APC mutations, were screened by denaturing gradient gel electrophoresis and direct sequencing to identify MYH germline mutations. RESULTS: Homozygous and compound heterozygous MYH mutations were identified in 40 patients (24%). No difference was found in the percentage of biallelic mutation carriers between patients with 10-99 polyps or 100-1000 polyps (29% in both groups). Colorectal cancer was found in 26 of the 40 patients with MAP (65%) within the age range 21 to 67 years (median 45). Complete endoscopic reports were available for 16 MAP patients and revealed five cases with gastro-duodenal polyps (31%), one of whom also presented with a duodenal carcinoma. Breast cancer occurred in 18% of female MAP patients, significantly more than expected from national statistics (standardised morbidity ratio = 3.75). CONCLUSIONS: Polyp numbers in MAP patients were equally associated with the attenuated and classical polyposis coli phenotypes. Two thirds of the MAP patients had colorectal cancer, 95% of whom were older than 35 years, and one third of a subset of patients had upper gastrointestinal lesions. Endoscopic screening of the whole intestine should be carried out every two years for all MAP patients, starting from age 25-30 years. The frequent occurrence of additional extraintestinal manifestations, such as breast cancer among female MAP patients, should be thoroughly investigated.

Adenomatous Polyposis Coli↗
PubMed2004

Genetic counseling for familial conditions during pregnancy: an analysis of patient characteristics.

Reproductive genetic counseling for a familial genetic risk factor preferably takes place before conception. However, of the women with a family history of genetic conditions who attend our department of clinical genetics, about 10-20% attend for the first time during a pregnancy. The current study aims to explore patient-related factors that may affect this late timing of reproductive genetic counseling. Consecutive pregnant (n = 100) and non-pregnant (n = 84) women visiting the department of clinical genetics for a genetic risk factor which was not age related completed a questionnaire immediately prior to the consultation. The questionnaire asked for (a) background characteristics, i.e. socio-demographic, obstetric, and disease characteristics (b) cognitive factors, i.e. initiative of referral, knowledge of the risk factor involved, risk perception, worry, child wish, attitudes toward abortion, and preferred participation in decision making, and (c) reasons for the timing of the consultation and for seeking genetic counseling. Pregnant women appeared to be higher educated, considered their children more often as healthy and were less often affected themselves, as compared to non-pregnant women. They also estimated their chance of having an affected child as lower, and they worried less. Furthermore, the initiative for referral was taken less often by the pregnant woman herself and more often by a medical worker. There were no major differences between the two study groups in knowledge, perceived severity of the risk factor, child wish, attitudes toward abortion, desired participation in decision making, and reasons to seek genetic counseling. Women indicated no specific reasons for their timing of referral for reproductive genetic counseling, e.g. during vs before pregnancy. Our data suggest that this timing of referral is not influenced predominantly by the women's level of knowledge. Rather, women's estimation of genetic risks and their degree of worry, which may be in accordance with the actual risk figures, seem to play a role in seeking genetic counseling. Although further studies are required, a more active role of health care providers seems warranted if we want to prevent genetic counseling for familial genetic conditions during pregnancy as much as possible.

Attitude to Health↗
PubMed2003

Atypical progeroid syndrome: an unknown helicase gene defect?

We describe a boy with chromosomal breakage syndrome, who died of hepatocellular carcinoma at the age of 17 years. Other findings included growth retardation, bilateral cataracts, premature graying of hair and elevated levels of urinary hyaluronic acid. Intellectual functions were normal. Although some manifestations were suggestive of Werner syndrome, the diagnosis could not be confirmed by molecular investigations. Therefore, this patient probably represents a provisionally unique syndrome, perhaps due to a mutation in a related (helicase) gene.

Adolescent↗
PubMed2001

[Prenatal genetic counseling in pregnancy: the importance of (early) timely referral ].

Three women aged 34, 23 and 39 years, who were respectively, 14, 12 and 8 weeks pregnant, requested genetic counselling due to grave genetic diseases in their families. The first woman chiefly wanted to be prepared; an investigation revealed no abnormalities and a healthy child was born. The second needed time to assimilate the information provided and terminated the pregnancy. For the third woman genetic screening was not possible in the short term and furthermore acceptation of the pregnancy was the biggest problem; she gave birth to a healthy child. In the Netherlands, about 800 to 1600 women every year request prenatal genetic counselling when they are already pregnant. The disadvantages of this late timing are the disquiet and uneasiness, the lost options and the time pressure under which difficult decisions have to be taken. Causes of this are a lack of genetic knowledge and psychosocial aspects. Ideally, genetic counselling that deals with reproductive issues should take place prior to conception.

Abortion, Eugenic↗
PubMed2000

A case of methemoglobinemia type II due to NADH-cytochrome b5 reductase deficiency: determination of the molecular basis.

Clinical, biochemical and molecular findings in a patient with methemoglobinemia type II are described. Furthermore, a comparison between methemoglobinemia type I and type II, both caused by a deficiency of NADH-cytochrome b5 reductase (b5R), is made. Although the clinical pictures of type I and II are strikingly different, mutations in the diaphorase (DIA1) gene located on chromosome 22 have been described in both types. In the present patient, two newly identified mutations, both leading to a stop codon in exon 4 (Gln77Ter) and in exon 6 (Arg160Ter), were found. Identification of different mutations at different positions in the DIA1 gene might shed light on the clinical and biochemical differences between methemoglobinemia type I and type II.

Child↗
PubMed1999

Unexplained aplastic anaemia, immunodeficiency, and cerebellar hypoplasia (Hoyeraal-Hreidarsson syndrome) due to mutations in the dyskeratosis congenita gene, DKC1.

Hoyeraal-Hreidarsson (HH) syndrome is a multisystem disorder affecting boys characterized by aplastic anaemia (AA), immunodeficiency, microcephaly, cerebellar-hypoplasia and growth retardation. Its pathogenesis is unknown. X-linked dyskeratosis congenita (DC) is an inherited bone-marrow-failure syndrome characterized by skin pigmentation, nail dystrophy and leucoplakia which usually develop towards the end of the first decade of life. AA occurs in >90% of cases of DC. We speculated that mutations in the gene responsible for X-linked DC (DKC1) may account for the HH syndrome, due to the phenotypic similarities between the disease in respect of AA and gender bias. We therefore analysed the DKC1 gene in two HH families. In one family a nucleotide change at position 361(A --> G) in exon 5 was found in both affected brothers; in the other family a nucleotide change at position 146(C --> T) in exon 3 was found in the affected boys. The finding of these two novel missense DKC1 mutations demonstrates that HH is a severe variant of DC. They also show that mutations in DKC1 can give rise to a very wide clinical spectrum of manifestations. Boys with unexplained AA or immunodeficiency should be tested for mutations in DKC1 even though they may lack diagnostic features of DC.

Amino Acid Substitution↗
PubMed1999

Point mutations throughout the GLI3 gene cause Greig cephalopolysyndactyly syndrome.

Greig cephalopolysyndactyly syndrome, characterized by craniofacial and limb anomalies (GCPS; MIM 175700), previously has been demonstrated to be associated with translocations as well as point mutations affecting one allele of the zinc finger gene GLI3. In addition to GCPS, Pallister-Hall syndrome (PHS; MIM 146510) and post-axial polydactyly type A (PAP-A; MIM 174200), two other disorders of human development, are caused by GLI3 mutations. In order to gain more insight into the mutational spectrum associated with a single phenotype, we report here the extension of the GLI3 mutation analysis to 24 new GCPS cases. We report the identification of 15 novel mutations present in one of the patient's GLI3 alleles. The mutations map throughout the coding gene regions. The majority are truncating mutations (nine of 15) that engender prematurely terminated protein products mostly but not exclusively N-terminally to or within the central region encoding the DNA-binding domain. Two missense and two splicing mutations mapping within the zinc finger motifs presumably also interfere with DNA binding. The five mutations identified within the protein regions C-terminal to the zinc fingers putatively affect additional functional properties of GLI3. In cell transfection experiments using fusions of the DNA-binding domain of yeast GAL4 to different segments of GLI3, transactivating capacity was assigned to two adjacent independent domains (TA(1)and TA(2)) in the C-terminal third of GLI3. Since these are the only functional domains affected by three C-terminally truncating mutations, we postulate that GCPS may be due either to haploinsufficiency resulting from the complete loss of one gene copy or to functional haploinsufficiency related to compromised properties of this transcription factor such as DNA binding and transactivation.

Animals↗
PubMed1999

Familial cryptic translocation between chromosomes 2qter and 8qter: further delineation of the Albright hereditary osteodystrophy-like phenotype.

Recently five patients with an Albright hereditary osteodystrophy (AHO)-like phenotype were reported to have a subtelomeric deletion of the long arm of chromosome 2. These patients showed a striking resemblance to a number of patients from a large pedigree known to us for a long time. After molecular confirmation of a subtelomeric deletion in one patient, FISH analysis was used and a cryptic translocation between the long arms of chromosomes 2 and 8, t(2;8)(q37.3;q24.3), was detected. Remarkably, five proven and 10 probable cases with a 2qter deletion were found in the family, but none with an 8qter deletion. This was not explained by increased fetal loss. The major clinical characteristics of terminal 2q deletion are a short, stocky build, round face, sparse hair, deeply set eyes, bulbous nose, thin vermilion border, brachymetaphalangism, seizures, and developmental delay. A specific behavioural phenotype consisting of periods of hyperkinesia and aggression can develop with age. The overall phenotype is sufficiently characteristic to allow clinical recognition. The cytogenetic and molecular studies did not narrow down the common deleted region. Both testing of additional 2q markers and characterisation of other AHO-like patients with 2q37 microdeletions may help to define the candidate gene region.

Adolescent↗
PubMed1997

Tandem duplication of 11p12-p13 in a child with borderline development delay and eye abnormalities: dose effect of the PAX6 gene product?

We report on a girl with a duplication of chromosome band 11p12-->13, which includes the Wilms tumor gene (WT1) and the aniridia gene (PAX6). The girl had borderline developmental delay, mild facial anomalies, and eye abnormalities. Eye findings were also present in most of the 11 other published cases with partial trisomy 11p, including 11p12-->13. Recently, it was shown that introduction of additional copies of the PAX6 gene into mice caused very variable eye abnormalities. Therefore, a PAX6 gene dosage effect is likely to be present in mice and humans. The central nervous system may be less sensitive to an altered PAX6 gene dosage, which is consistent with the borderline developmental delay in the present patient. Urogenital abnormalities were absent in this patient and in most of the other patients with partial trisomy of 11p. Therefore, the effect of a WT1 gene duplication on the embryological development of the urogenital tract remains uncertain.

Chromosome Aberrations↗
PubMed1997

[Genetic counseling: should side issues become main issues?].

Three people applied for genetic counselling, but during the consultations the clinical geneticist discovered other problems for which advice could have been given but was not asked. This caused a serious dilemma. The first person was a woman who wanted to know the risks of epilepsy for her potential offspring, but then it became clear that she appeared to have Huntington's disease in the family. The second person was a man who wanted to know about the genetic risks for his offspring of a borderline psychiatric disorder, but the geneticist, seeing that the partner had severe limb defects, wondered whether these were caused by a genetic disorder. The third patient was a pregnant woman who came asking about the risks caused by mental retardation in one of her ancestors, but who appeared to be a heavy drinker and user of cocaine and ecstasy. In dealing with such 'secondary' problems, it should be kept in mind that persons seeking advice must decide for themselves whether or not they want to be informed regarding these problems or not.

Adult↗
PubMed1997

Parental somatic and germ-line mosaicism for a FBN2 mutation and analysis of FBN2 transcript levels in dermal fibroblasts.

Congenital contractural arachnodactyly (CCA) is an autosomal dominant disorder that is phenotypically related to the Marfan syndrome. CCA has recently been shown to result from mutations in the FBN2 gene, which encodes an elastin-associated microfibrillar protein called fibrillin-2. Two siblings are reported here with classic manifestations of CCA with unaffected parents. Analysis of the FBN2 cDNA from dermal fibroblasts from one of the affected siblings revealed a heterozygous exon splicing error deleting nt 3722-3844 of the FBN2 mRNA. This cDNA deletion resulted in selective removal of one of the 43 calcium-binding EGF-like domains of the fibrillin-2 protein. Analysis of the FBN2 gene in the affected siblings' DNA indicated that the splicing error resulted from an A-to-G transition 15 nt upstream from the 3' splice site of the intron. The genomic mutation resulting in the splicing error alters a putative branch point sequence important for lariat formation, an intermediate structure of normal splicing. The mutation was detectable in DNA from the father's hair bulbs and buccal cells but not his white blood cell DNA, indicating that the father was a somatic mosaic. Analysis of transcript levels by use of dermal fibroblasts from the proband demonstrated that the FBN2 allele containing the exon deletion was expressed at a higher level than the allele inherited from the mother. These results indicate that FBN2 exon splicing errors are a cause of CCA, furthering the understanding of the molecular basis of this disorder. In addition, the demonstration of gonadal mosaicism in the FBN2 gene is important for accurate genetic counseling of families with sporadic cases of CCA. Finally, the preferential expression of the mutated FBN2 allele in dermal fibroblasts may have implications for understanding the pathogenesis and rarity of CCA.

Alleles↗
PubMed1996

[Smith-Lemli-Opitz syndrome; a special defect in cholesterol metabolism].

In a male neonate dysmaturity, microcephalia, a high nasal bridge, a long philtrum, broad dental ridges, schisis of the palatum molle, retrognathia, a small penis with a chorda, a small scrotum, bilateral inguinal hernia and bilateral syndactyly of the second and third toes were observed. The presence of the Smith-Lemli-Opitz (SLO) syndrome was suspected. By gas chromatography a severely decreased plasma cholesterol level (0.27 mmol/l) was found and an increased plasma 7-dehydrocholesterol level (0.24 mmol/l). The SLO syndrome is caused by a block in the cholesterol biosynthesis due to the autosomal recessive deficiency of 7-dehydrocholesterol reductase. The patient's condition improved with use of a cholesterol-enriched diet.

Abnormalities, Multiple↗
PubMed1996

Further delineation of the acro-renal-ocular syndrome.

A triad of acral, renal, and ocular abnormalities was reported previously in four families. We report on a fifth family, in which a mother, one of her four sons and one of her two daughters are affected. Major findings in the acro-renal-ocular syndrome are upper limb abnormalities, mainly thumb hypoplasia, eye abnormalities such as coloboma and Duane anomaly and renal migration defects. A close embryological-temporal relationship between the traits of this entity suggest a common monogenic cause. The pattern of inheritance is probably autosomal dominant. Because of a wide variability of clinical manifestations, recognition of the syndrome in individual cases may be difficult.

Adult↗
PubMed1996

Cataracts, radiculomegaly, septal heart defects and hearing loss in two unrelated adult females with normal intelligence and similar facial appearance: confirmation of a syndrome?

Two unrelated, adult females with normal intelligence are described. They show a similar clinical picture with a long and narrow face, congenital cataract, microphthalmia, microcornea, a high nasal bridge, a short nose, a broad nasal tip, a long philtrum, bilateral hearing loss, persistent primary teeth, oligodontia, variable root length including dental radiculomegaly, heart defects and cutaneous syndactyly of the 2nd-3rd toes. Abnormalities present in only one of the two patients were a cleft palate and a transverse vaginal septum, respectively. There are numerous similarities between our two patients and the family described by Wilkie et al. ((1993): Clin Dysmorphol 2: 114-119) and all may be examples of the same entity.

Abnormalities, Multiple↗
PubMed1996

Two supernumerary marker chromosomes, derived from chromosome 6 and 9, in a boy with mild developmental delay.

We report on a boy with two supernumerary marker chromosomes which were identified by fluorescence in situ hybridization and derived from chromosome 6 and 9. In lymphocytes, a mosaic karyotype was found: 46,XY (17%)/ 47,XY,r(6) (24%)/47,XY,r(9) (20%)/48,XY,r(6),r(9) (39%). Only minor dysmorphic features and mild developmental delay were present. Despite extensive fluorescence in situ hybridization studies using a large panel of probes, we were unable to characterize the marker chromosomes in more detail, mainly because no probes for the chromosome regions involved were available to us. In order to reach a better understanding of the clinical relevance of small supernumerary marker chromosomes, it will be necessary to create a widely available set of probes, covering all chromosome regions.

Child, Preschool↗