A novel gamma-sarcoglycan mutation causing childhood onset, slowly progressive limb girdle muscular dystrophy

Limb girdle muscular dystrophy is a heterogeneous group of disorders. One autosomal recessive subtype, LGMD2C, has been linked to chromosome 13, and is caused by gamma-sarcoglycan deficiency in muscle. This report describes a novel missense mutation identified in a large consanguineous Dutch family with LGMD. This mutation leads to reduction of gamma-sarcoglycan, and gives rise to a childhood-onset, slowly-progressive dystrophy.

[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.

Genetic counseling for hereditary cancer: a pilot study on experiences of patients and family members

Recent advances in the identification of genetic abnormalities associated with certain types of cancer have stimulated the development of screening and counseling programs for hereditary and familial forms of cancer. In 1995, such a program was established in a collaboration between three familial cancer clinics in Amsterdam. Given the potential impact of genetic screening and counseling on the psychosocial health of participants, it was considered essential that the program be evaluated from its inception to determine the participants' satisfaction with the services provided. A pilot study was initiated in which individuals who received genetic counseling for cancer were asked to provide feedback on the perceived quality of the services provided, and to identify areas in which additional services may be required. Preliminary results based on 36 counseled individuals indicated generally high levels of satisfaction with the care provided by the clinical geneticist and with the procedures at the familial cancer clinics. Several areas were identified that deserve additional attention: (1) the role of the family doctor in the genetic counseling; (2) communication of information regarding the possible impact of genetic counseling and testing on daily life; (3) communication between the clinical geneticist and other health care workers, and (4) psychosocial support during and after the process of genetic counseling.

Human synaptonemal complex protein 1 (SCP1): isolation and characterization of the cDNA and chromosomal localization of the gene

Synaptonemal complexes (SCs) are structures that are formed between homologous chromosomes (homologs) during meiotic prophase. They consist of two proteinaceous axes, one along each homolog, that are connected along their length by numerous transverse filaments (TFs). The cDNA encoding one major component of TFs of SCs of the rat, rnSCP1, has recently been isolated and characterized. In this paper we describe the isolation and characterization of the cDNA encoding the human protein homologous to rnSCP1, hsSCP1. hsSCP1 and rnSCP1 have 75% amino acid identity. The most prominent structural features and amino acid sequence motifs of rnSCP1 have been conserved in hsSCP1. Most probably, hsSCP1 is functionally homologous to rnSCP1. The hsSCP1 gene was assigned to human chromosome 1p12-p13 by fluorescence in situ hybridization.

Maternal uniparental disomy for chromosome 22 in a child with generalized mosaicism for trisomy 22

We report on a case of generalized mosaicism for trisomy 22. At chorionic villus sampling (CVS) in the 37th week of pregnancy, a 47,XX,+22 karyotype was detected in all cells. The indication for CVS was severe unexplained symmetrical intrauterine growth retardation (IUGR) and a ventricular septal defect (VSD) was noted. In cultured cells from amniotic fluid taken simultaneously, only two out of ten clones were trisomic. At term, a growth-retarded girl with mild dysmorphic features was born. Lymphocytes showed a normal 46,XX[50] karyotype; both chromosomes 22 were maternal in origin (maternal uniparental disomy). Investigation of the placenta post-delivery using fluorescence in situ hybridization showed a low presence of trisomy 22 cells in only one out of 14 biopsies. In cultured fibroblasts of skin tissue, a mosaic 47,XX,+22[7]/46,XX[25] was observed. Clinical follow-up is given up to 19 months.

Prenatal diagnosis in the Netherlands. Dutch Working Party of Prenatal Diagnosis

Prenatal invasive diagnosis of genetic conditions in the Netherlands is well organised, based on uniform indications and has a sound financial structure. Facilities for fetal karyotyping and DNA analysis are available in the 8 academic centres. Prenatal diagnosis of metabolic diseases is mainly carried out in Rotterdam. Amniocentesis, transcervical and transabdominal chorionic villus sampling are carried out in all centres, including 4 subcentres. The national Working Party on Prenatal Diagnosis started in 1985 and is a useful platform for all obstetricians and geneticists involved in prenatal diagnosis.

Cytogenetic characteristics of ectopic pregnancy

During a 12 month period, tissue was collected from 30 surgically managed patients presenting with vital ectopic pregnancies. Chorionic villi of the removed tissue were successfully karyotyped by (semi-) direct chromosome technique in 22 cases. Only one abnormal chromosomal complement, a triploidy (69,XXX) was found. As controls, 10 cases of intrauterine pregnancies were investigated, all showing a normal karyotype. These findings do not suggest an important role for chromosome abnormalities in the aetiology of vital ectopic pregnancies.

The outcome of pregnancies with confined placental chromosome mosaicism in cytotrophoblast cells

Cytogenetic findings and outcome of pregnancy are reported in 108 cases in which confined placental mosaicism (CPM, n = 101) or generalized mosaicism (n = 7) was found at or after first-trimester chorionic villus sampling. In all samples, a (semi)direct cytogenetic analysis of cytotrophoblast cells was performed. Two pregnancies with CPM ended in a spontaneous abortion before 28 weeks (1.9 per cent). In 15 cases the pregnancy was terminated: eight cases were shown to be examples of CPM; seven cases can be considered as examples of generalized mosaicism. A normal cytogenetic result was obtained after follow-up amniocentesis in 88 of the remaining 91 cases. In three cases, no amniocentesis was performed but confirmation of a normal karyotype was obtained in other cells. One of the 91 pregnancies was nevertheless terminated for psychosocial reasons. One child died perinatally and another on the seventh day after birth. The birth weight is known for 89 children; the curve shows a normal distribution. In 11 of these children (12.3 per cent), the birth weight was found to be below the tenth centile. The outcome in a subgroup of eight pregnancies with CPM and involvement of chromosome 13, 16, or 22, however, revealed two fetal losses and four children with a birth weight below the tenth centile (75 per cent).

Supernumerary ring chromosome 20 characterized by fluorescence in situ hybridization

We report on a boy with mild dysmorphic features and developmental delay, in whom karyotyping showed an additional minute ring chromosome in 60% of metaphases. Fluorescence in situ hybridization (FISH) with a centromere specific probe demonstrated that the ring chromosome contained the centromeric region of chromosome 20. The ring was highlighted completely using a chromosome 20 painting probe. A cosmid probe for 20p 12-13 gave a positive signal and hybridization with an all-telomere probe showed on signal, suggesting a breakpoint in the 20p telomere. The results suggested that only a small part of 20q was involved in this ring. The ring was also detected in 18% of nuclei of a buccal smear. The phenotypic similarities of symptoms in the proband to patients with a (partial) trisomy 20p and the dissimilarities to symptoms in patients with (partial) trisomy 20q were in agreement with the FISH results.

Trisomy 3 mosaicism on CVS: case report with literature review and propositions for investigation and counseling

Chorionic villus sampling performed for advanced maternal age revealed trisomy 3 in 20% of mitoses studied after a semi-direct chromosomal harvest. Amniocytes and cord blood showed a non-mosaic 46,XY karyotype. The birthweight of the normal newborn was at the tenth percentile. Analysis of term placenta by cytogenetics and by fluorescent in situ hybridization (FISH) confirmed the presence of the trisomy 3 in 20% and 12%, respectively, of cells from two peripheral placental biopsies. Placental histology was heterogeneous, some portions showing immature, edematous and undervascularized villi. DNA analysis confirmed the biparental origin of the chromosomes 3 in the child, whose development is normal at 36 months.

Further delineation of the partial proximal trisomy 10q syndrome

We report on a girl with a partial duplication of the proximal part of the long arm of chromosome 10, confirmed by chromosome painting. The phenotypic findings are compared to those found in six other published cases with the same karyotype. Recognition of a specific partial proximal trisomy 10q syndrome seems to be possible, consisting of mild to moderate developmental delay, postnatal growth retardation, microcephaly, prominent forehead, small and deep set eyes, epicanthus, upturned nose, bow shaped mouth, micrognathia, thick and flat helices of the ears, and long, slender limbs. Severe ocular malformations are possibly part of the syndrome. No major phenotypic differences were seen between patients with a duplication of segment 10q11-->10q22 and patients with a duplication of 10q21-->10q22.

The preserving of chorionic villi before establishing long-term cell cultures for cytogenetic analysis

The possibility of preserving intact chorionic villi in culture medium for up to 7 days before establishing long-term cultures for prenatal chromosome analysis is demonstrated. The preserving itself had no negative effect on the growth capacity of the mesenchymal cells.

Pregnancy outcome after transcervical CVS with a flexible biopsy forceps: evaluation of risk factors

The pregnancy outcome of 1936 women who had transcervical chorionic villus sampling (CVS) with a flexible biopsy forceps was evaluated. Follow-up until 4 weeks after delivery was 99.4 per cent. Various patient- and procedure-related risk factors for spontaneous loss (fetal or neonatal death) were analysed using stepwise logistic regression analysis. The overall spontaneous loss rate was 4.5 per cent. Factors found to be significantly associated with spontaneous loss were quantity of villi < or = 15 mg (relative risk (RR) 2.13), a history of first-trimester miscarriage (RR 1.87) or delivery between 16 and 27 weeks (RR 3.87), cervical culture positive for anaerobes (RR 4.52) or group B streptococcus (RR 3.62), post-procedural bleeding > 3 days (RR 1.99), and multiple insertions (RR 2.64). Significant differences in loss rates between individual operators were found. A learning effect was not present. There were no infants born with terminal transversal limb anomalies in our series. We conclude that knowledge about significant risk factors for spontaneous loss after CVS is important both for obstetricians carrying out CVS procedures and for women seeking prenatal diagnosis.

46,XY,dup(10q) in direct CVS preparation and mosaic 48,XXXY,dup(10q) in CVS long-term culture and fetal tissue

Chorionic villus sampling (CVS) was performed on a 40-year-old woman at 9 1/2 menstrual weeks because of advanced maternal age. The direct preparation showed 46,XY,dup(10)(q11.2q23.2). CVS long-term culture and fetal tissue revealed a rare additional abnormality: 48,XXXY,dup(10)(q11.2q23.2). This abnormality represented the major cell line (> 85 per cent in 691 cells) in an (XY)/XXY/XXXY/(XXXXY) mosaic (all cell lines presumably bearing the dup(10q); the presence of XY and XXXXY cell lines is uncertain). To our knowledge, this is the first report of trisomy 10q11-q23 and of prenatally detected 48,XXXY in chorionic villi. The mosaic could have resulted from early post-zygotic non-disjunctions in a 46,XY,dup(10q) or 47,XXY,dup(10q) zygote. The results from DNA studies of four polymorphisms, mapped to Xp and Xq, support this theory. The literature on prenatally detected cases with sex chromosome tetrasomy and pentasomy and those with additional autosomal abnormalities is reviewed. The reported case underlines the problem of false-negative findings when only direct CVS preparations are karyotyped.

Molecular cytogenetic analysis of term placentae suspected of mosaicism using fluorescence in situ hybridization

In first-trimester chorionic villus sampling (CVS) for prenatal diagnosis, abnormal chromosomal findings, such as mosaicism, trisomies, or suspect abnormal karyotypes, are found more frequently than at amniocentesis. The fact that these chromosomal abnormalities do not always reflect the fetal karyotype but may be restricted to the placenta is a major problem in diagnosis and counselling. In this paper we present the results of fluorescence in situ hybridization (FISH) studies on interphase nuclei of three term placentae investigated because of false-positive findings at first-trimester CVS. The chorionic villi of the first case showed a mosaic chromosome pattern involving a trisomy 10 cell line and a normal cell line, those of the second case a total trisomy 8 cell line, while in the third case a complete monosomy X was found. Follow-up amniocentesis in each of these three cases revealed a normal karyotype. By using FISH, we were able to confirm the presence of the aberrant cell lines, which were all confined to one part of the placenta. FISH on interphase nuclei allows the investigation of large numbers of cells for the existence of numerical chromosome aberrations in a quick and reliable way.

High-resolution chromosomal localization of the human calcitonin/CGRP/IAPP gene family members

We report the high-resolution localization of the human calcitonin/CGRP genes, CALCA, CALCB, and the pseudogene CALCP, to a 220-kb SacII fragment on chromosome 11p15.2-p15.1, using prometaphase fluorescence in situ hybridization (FISH), two-color interphase FISH, and pulsed-field gel electrophoresis analysis. The related islet amyloid polypeptide (IAPP) gene was assigned to human chromosome 12p12.3-p12.1. The results support an evolutionary relationship between the calcitonin/CGRP genes and the IAPP gene and between parts of human chromosomes 11 and 12.

Jejunal atresia related to the use of methylene blue in genetic amniocentesis in twins

OBJECTIVE

To calculate the incidence of jejunal atresia in newborns in The Netherlands. To study the relation between the occurrence of jejunal atresia and genetic amniocentesis to determine a possible iatrogenic cause for the unexpected high incidence of this anomaly in twins.

DESIGN

Retrospective study.

SUBJECTS

Eighty-nine consecutive twin pregnancies in which amniocentesis had been performed for prenatal diagnosis. In 86 methylene blue solution had been used to mark the amniotic cavity that was punctured first.

MAIN OUTCOME MEASURE

The occurrence of jejunal atresia in one of the two twin infants.

RESULTS

The incidence of jejunal atresia at birth in The Netherlands is estimated to be 1 in 14,000. This anomaly occurred in 17 out of 89 twin pregnancies (19%). In 15 of the 17 it was possible to determine which of the two children had been exposed to intra-amniotic methylene blue. In all 15 pregnancies, the infant exposed to the dye was suffering from jejunal atresia.

CONCLUSION

A causal relation between the use of methylene blue in second trimester amniocentesis and the occurrence of jejunal atresia is strongly suggested. We recommend that no dyes should be injected into the amniotic sac.

High-resolution localization of 69 potential human zinc finger protein genes: a number are clustered

In this study, we describe the identification and partial characterization of 101 potential human zinc finger protein genes (ZnFPs). These sequences were isolated by hybridization of cosmids, obtained from mouse-human cell lines enriched for chromosome 11p, with an oligonucleotide specific for the "link" sequence between contiguous zinc fingers. Sixty-nine of these cosmids were regionally localized to human prometaphase chromosomes by in situ hybridization. The localization of these cosmids suggests that a number of finger protein genes occur in linked clusters. Their assignment to chromosomes 3p, 11p, 19p, 19qter, 20p, and 21q makes them valuable as markers or "candidate" genes for diseases associated with these chromosome regions.

Is placental mosaicism associated with poor perinatal outcome?

In 37 pregnancies with placental mosaicism detected at first-trimester chorionic villus sampling in 2000 pregnancies, two pregnancies (5.4 per cent) ended in a spontaneous abortion at 15 weeks (46,XX 47,XX, + 16) and in a perinatal loss in a term pregnancy (46,XY/47,XY, + 10), respectively. The outcome of the other 35 pregnancies was normal. The total pregnancy loss rate before 28 weeks in the first 1000 pregnancies was previously reported to be 3.6 per cent.