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1.
Unstable expansion of the CTG repeats in the 3' untranslated region encoding a member of the protein kinase family in the q13.3 band on chromosome 19 is a mutation specific for myotonic dystrophy. To examine the correlation between clinical expression and CTG trinucleotide repeat length, we carried out Southern blot analysis in a family with myotonic dystrophy. In this pedigree, the expanded CTG repeats were transmitted maternally. The mother had three female children. The mother had about 200 CTG repeats, and the number of repeats for each child was about 800, 1500 and 1600 in birth order. The mother and the patient with 800 repeats were unaware of muscle weakness or myotonia. Symptoms were present from age 3 years in the patient with 1500 repeats and from birth in the one with 1600 repeats. Although the mother menstruated regularly, the patients with 800 and 1500 repeats both menstruated irregularly, and the one with 1600 repeats has never menstruated. The age of onset and severity of the disease were correlated with the size of the expanded repeats. Endocrinological studies revealed that the basal levels of the gonadotropins, PRL and E2 were within normal range, and a pituitary response to LHRH was observed. These data suggest that the amenorrhea and menstrual irregularities were caused by a suprahypophyseal dysfunction. When expanded CTG repeats are transmitted maternally, abnormal products resulting from the metabolic disturbance in the affected mother may harm the fetus in utero. A heterozygous fetus, who has more CTG repeats, may be unable to metabolize the pathologic products sufficiently and therefore may become more severely affected. This may explain the exclusive maternal transmission of congenital myotonic dystrophy.  相似文献   

2.
The genetic basis for myotonic dystrophy (DM) is a CTG trinucleotide repeat expansion. The number of CTG repeats commonly increases in affected individuals of successive generations, in association with anticipation. We identified a large DM family in which multiple members had minimal CTG repeat expansions, and in which the number of CTG repeats remained in the minimally expanded range through at least three, and possibly four, generations. This relative stability of minimal CTG repeat expansions may help to maintain the DM mutation in the population.  相似文献   

3.
OBJECTIVE: To increase the knowledge about pregnancy and delivery in women with certain muscle diseases, which is important for obstetric management and family planning of affected women. DESIGN: The obstetric histories of patients with facioscapulohumeral (FSH) muscular dystrophy, limb-girdle (LG) muscular dystrophy, and congenital myopathies (CM) were retrospectively evaluated using questionnaires and medical reports. PATIENTS: The condition of 27 patients with different myopathies (FSH muscular dystrophy, n = 11; LG muscular dystrophy, n = 9; and CM, n = 7 [subdivided into 5 patients with central core disease, 1 patient with cytoplasmic bodies, and 1 patient with unspecified myopathy]) were ascertained from January 1, 1992, to December 31, 1994, through departments of neurology and human genetics, and the German self-support group for muscle diseases. Fifty-eight gestations resulting in 52 live births were reviewed. RESULTS: Miscarriages were reported in 3 of 26 gestations in 11 patients with FSH dystrophy, whereas 3 of 15 pregnancies in patients with LG dystrophy were terminated. Preterm births occurred in 2 patients with FSH dystrophy and in 3 patients with CM. Operative deliveries (vaginal operation or cesarean section) were performed in 6 of 23 gestations in patients with FSH dystrophy (1 emergency section), in 5 of 12 patients with LG dystrophy (2 emergency sections), and in 3 of 17 deliveries in patients with CM. Patients with FSH dystrophy generally coped well with their muscle disease in pregnancy and after delivery; however, 4 women were stated to have difficulties in caring for their families. The situation differed in LG dystrophy, where most women (5 of 9) experienced worsening of weakness in pregnancy and required assistance after delivery. In the patients with CM, 3 women experienced a deterioration during pregnancy, and 4 patients reported difficulties after delivery. CONCLUSIONS: No deleterious outcome of pregnancy and labor was observed in this series of patients with muscular dystrophy or CM, although operative deliveries were more frequent. A significant aggravation of symptoms in gestation is more likely to occur in patients with early-onset and progressive myopathy than in those with stable disease courses.  相似文献   

4.
Myotonic dystrophy (DM) is caused by an expansion of a CTG repeat sequence in the 3' noncoding region of a protein kinase gene (DMPK) at 19q13.3. We used in situ hybridization to analyse the replication timing of the genomic region containing DMPK in fibroblasts and myoblasts from controls and myotonic dystrophy patients. In this method the relative proportion of singlet to doublet hybridization signals is used to infer the relative time of replication of specific loci or regions. Our results show that in cells from normal individuals approximately 65% of signals appear as doublets, indicating early replication. In DM patients with a number of CTG repeats ranging from about 600-1800 we observed a significant increase of singlet-doublets compared to the background level. These results suggest the existence of replication alternations and/or structural differences between the normal and mutant alleles induced by the presence of the DM mutation.  相似文献   

5.
Myotonic dystrophy (DM) is associated with an expansion of an unstable (CTG)n repeat in the 3' untranslated region of the DM protein kinase (DMPK) gene on chromosome 19q13.3. We studied six patients from two families who showed no expansions of the repeat, in spite of their clinical diagnosis of DM. These patients had multi-systemic manifestations that were distinguishable from those seen in other myotonic disorders, including proximal myotonic myopathy (PROMM). In one additional family, two symptomatic members showed no expanded (CTG)n repeats, while their affected relatives had the expanded repeats. DM haplotype analysis failed to exclude the DMPK locus as a possible site of mutation in each family; however, DMPK mRNA levels were normal. We conclude that a mutation(s) other than the expanded (CTG)n repeat can cause the DM phenotype. The mutation(s) in these families remain(s) to be mapped and characterized.  相似文献   

6.
We studied the relationship between muscle pathology and the number of trinucleotide (CTG) repeats observed in lymphocytes and biopsied muscle tissues from patients with dystrophia myotonica (DM). The diameter of type 1 muscle fibers was smaller than that of type 2 fibers in all patients. The diameter and proportion of each muscle fiber type were related to the patient's age, but not to the number of trinucleotide (CTG) repeats of DM kinase in biopsied muscles. On the other hand, the proportion of type 1 fibers with central nuclei was closely related to the number of trinucleotide (CTG) repeats in muscles. These findings suggest that DM kinase abnormalities influence the muscle nuclei, and increase the number of central nuclei.  相似文献   

7.
Increasing numbers of young women with ovarian failure and women of advanced reproductive age (> 40 yrs) utilize oocyte donation to treat their infertility. In both groups, women who become pregnant frequently experience multiple gestation, occurring in up to 30% of pregnancies. Advanced maternal age and high-order multiple gestations are associated with an increased risk for obstetric complications. We reviewed the pregnancies of patients with high-order multiple gestations (> or = 3 gestational sacs) with respect to their antepartum course and neonatal outcomes. Mothers were divided into two groups according to age at conception; Group I (> or = 40 yr, n = 20) and Group II (< 40 yr, n = 10). These 30 high-order multiple gestations were found among 127 successful oocyte donation cycles (23.6% of all pregnant patients). Data regarding pregnancy outcomes were gained by chart review and telephone interview. Results demonstrated spontaneous reductions in the number of implantation sites were similar between groups (Group I: 21.4% vs. Group II: 17.6%). Multifetal pregnancy reduction (MFPR) was more often chosen by older women (Group I: 45% vs. Group II: 10%; P < 0.05). Antenatal complications were commonly experienced by both groups (> 80%) as were operative deliveries (> 85%). However, neonatal outcomes were generally good, with only one death occurring in the 79 delivered infants (1.3%). We conclude transferring supernumerary embryos to women undergoing ovum donation places patients at great risk for high-order multiple gestations. These pregnancies are associated with increased antenatal and neonatal complications. Although advanced maternal age is normally an added risk factor, well-screened older patients carrying high-order multiple gestations experienced similar outcomes as younger mothers.  相似文献   

8.
BACKGROUND: Family studies of schizophrenia and bipolar affective disorder provide evidence for genetic anticipation, which (in common with a number of mendelian disorders), may be caused by triplet repeat expansion. This hypothesis is strengthened by evidence from repeat expansion detection (RED) analysis revealing association between the psychoses and long CAG/CTG trinucleotide repeats. METHODS: We performed RED on Han Chinese subjects with schizophrenia (82), bipolar affective disorder (43), and normal controls (61), using a CTG10 oligonucleotide. RESULTS: Comparison between cases and controls revealed no significant association between long repeats and affected status. We also found no detectable association with age at onset and repeat length in either bipolar affective disorder or schizophrenia. Overall, the size distribution of CAG/CTG repeats in Chinese subjects was not significantly different from those reported previously for Caucasian subjects. CONCLUSIONS: These findings indicate that CAG/CTG repeat expansion is not likely to be a major etiological factor for psychosis in Chinese populations.  相似文献   

9.
Myotonic dystrophy (DM) is a highly variable multisystemic disease belonging to the rather special class of trinucleotide expansion disorders. DM results from dynamic expansion of a perfect (CTG)n repeat situated in a gene-dense region on chromosome 19q. Based on findings in patient materials or cellular and animal models, many mechanisms for the causes and consequences of repeat expansion have been proposed; however, none of them has enjoyed prolonged support. There is now circumstantial evidence that long (CTG)n repeats may affect the expression of any of at least three genes, myotonic dystrophy protein kinase (DMPK), DMR-N9 (gene 59), and a DM-associated homeodomain protein (DMAHP). Furthermore, the new findings suggest that DM is not a simple gene-dosage or gain-or-loss-of-function disorder but that entirely new pathological pathways at the DNA, RNA, or protein level may play a role in its manifestation.  相似文献   

10.
The aim of the study was to determine the clinical epidemiology of genitourinary fistulae as seen at Komfo Anokye Teaching Hospital in Kumasi, Ghana. A retrospective study was carried out from the hospital records and operative reports of all patients with genitourinary fistulae seen at Komfo Anokye Teaching Hospital between January 1977 and December 1992. Patient age, parity, type of fistula and cause of fistula were abstracted from the medical records. There were 164 cases of genitourinary fistula managed during the study period. There were 150 fistulae due to obstetric causes (91, 5%), the vast majority of which were due to prolonged obstructed labor (121 cases, 73.8% of all fistulae), with a minority related to complications of lower-segment cesarean section (14 cases, 8.5% of all fistulae). In 5 cases (3.1%) patients developed a rectovaginal fistula owing to perineal tears and prolonged obstructed labor. During this time period there were 157,449 deliveries, giving an obstetric fistula rate of 1 fistula per 1000 deliveries. Obstetric fistulae were most common at the extremes of reproductive age and parity Fourteen additional fistulae (8.5% of all cases) were due to gynecologic causes, most commonly from surgical injury occurring at the time of abdominal hysterectomy for leiomyomata uteri (12 cases, 7.3% of all fistulae). It was concluded that in Kumasi, Ghana, obstetric trauma from prolonged obstructed labor is the most common cause of genitourinary fistula formation. Such fistulae occur in older multiparous women as well in young primigravidae. Obstructed labour can, and does, occur in women who have previously undergone uneventful vaginal delivery. Birth attendants should be aware of that fact. Prompt referral for obstetric intervention should be made in obstructed labor, irrespective of the age and parity of the patient.  相似文献   

11.
A major question about the pathogenesis of myotonic dystrophy (DM) is how the (CTG)n repeat mutation alters expression of the DM gene and how that is related to disease causation. Most previous studies have found a decrease in DM RNA and protein in patient tissue. In contrast to these reports we find, unexpectedly, that independent of the size of the CTG repeat: (1) there are equal levels of RNA products of mutant and normal alleles, and (2) levels of Mt-PK in skeletal muscle from DM patients is unaltered from normal. These findings are consistent with the recent hypothesis that mutant DM DNA or RNA may cause disease by disrupting the function of other, yet unidentified, genes.  相似文献   

12.
OBJECTIVES: We assessed perinatal morbidity and mortality of prolonged pregnancies (> or = 294 days) compared with those of term gestations. We also evaluated the impact of induction of labor compared with spontaneous onset of labor. STUDY DESIGN: This observational study included consecutive cases treated at Chicago Lying-In Hospital from July 1980 to December 1984. Complications, presence of meconium, indications for cesarean section, mode of delivery, perinatal morbidity (and mortality), meconium aspiration, and duration of labor were compared with those in the total hospital population, in infants weighing > or = 2500 gm, and within prolonged gestation groups; spontaneous onset and induced ("active management") labors were also compared. The chi 2 analysis was used. RESULTS: Of 12,930 deliveries there were 707 prolonged gestations (5.5%) and 10,698 with infants > or = 2500 gm. Among the prolonged gestations 67% were in multiparous women and 33% in primiparous women. Labor started spontaneously in 62%, and 38% underwent induction; the overall cesarean section rate was 17% with similar indications in both spontaneous onset and induction groups. Meconium was present in 34%; it was present in 23% of inductions, which is fewer (p < 0.01) than among those with spontaneous onset of labor (40%). Also there were fewer depressed neonates at 5 minutes (p = 0.03) among inductions. Meconium aspiration was seen in 24, with nine deaths. The perinatal mortality was 14 per 1000 (corrected 12.7/1000), significantly more than in the general population. Among those with spontaneous onset of labor it was 20.5 per 1000; there were no deaths among inductions. Postpartum maternal morbidity was 16% among cesarean sections and 4% among vaginal deliveries. CONCLUSIONS: Prolonged gestation has a high perinatal morbidity and mortality rate. All perinatal deaths were observed among patients whose labor started spontaneously. "Active management" (induction at 42 weeks) did increase the primary cesarean section rate compared with that of the general obstetric population; it did not do so among prolonged gestations and prevented perinatal deaths in this group. From this experience an active approach seems justified.  相似文献   

13.
The CTG repeat number in the 3'-untranslated region of the myotonin protein kinase (MTPK) gene varies between 5 and 37 in normal individuals, whereas myotonic dystrophy (DM) patients have expansions from 50 to 3000 copies. However little is known about the molecular mechanisms or the genetic control of the expansion of triplet repeats. To explain the dynamic mutation mechanism and high prevalence in the population, slippage theory, multistep model and meiotic drive hypothesis have been proposed. Recent studies have shown that repeat expansion may affect neighboring genes (59 gene and DMAHP gene), or exert its effect at the RNA level by modulating the binding of (CUG)n-RNA binding proteins which are required for the maturation, stability and translation of specific mRNAs.  相似文献   

14.
The properties of duplex CTG.CAG and CGG.CCG, which are involved in the etiology of several hereditary neurodegenerative diseases, were investigated by a variety of methods, including circularization kinetics, apparent helical repeat determination, and polyacrylamide gel electrophoresis. The bending moduli were 1.13 x 10(-19) erg.cm for CTG and 1.27 x 10(-19) erg.cm for CGG, approximately 40% less than for random B-DNA. Also, the persistence lengths of the triplet repeat sequences were approximately 60% the value for random B-DNA. However, the torsional moduli and the helical repeats were 2.3 x 10(-19) erg.cm and 10.4 base pairs (bp)/turn for CTG and 2.4 x 10(-19) erg.cm and 10.3 bp/turn for CGG, respectively, all within the range for random B-DNA. Determination of the apparent helical repeat by the band shift assay indicated that the writhe of the repeats was different from that of random B-DNA. In addition, molecules of 224-245 bp in length (64-71 triplet repeats) were able to form topological isomers upon cyclization. The low bending moduli are consistent with predictions from crystallographic variations in slide, roll, and tilt. No unpaired bases or non-B-DNA structures could be detected by chemical and enzymatic probe analyses, two-dimensional agarose gel electrophoresis, and immunological studies. Hence, CTG and CGG are more flexible and highly writhed than random B-DNA and thus would be expected to act as sinks for the accumulation of superhelical density.  相似文献   

15.
Trinucleotide microsatellites are widespread in the human and other mammalian genomes. Expansions of unstable trinucleotide repeats have been associated so far with a number of different genetic diseases including fragile X, myotonic dystrophy (DM) and Huntington disease. While ten possible trinucleotides can occur at the DNA level, only CTG and CCG repeats are involved in the disorders described so far. However, the repeat expansion detection (RED) technique has identified additional large repeats of ATG, CCT, CTT, and TGG of potentially pathological significance in the human genome. We now show that conclusive information about the chromosomal localization of long trinucleotide repeats can be achieved in a relatively short time using fluorescence in situ hybridization (FISH) with biotin-labelled trinucleotide polymers. Large CTG expansions (> 1 kb) in DM and an unstable (CTG)306 repeat in a patient with schizophrenia were detected by eye through the microscope without electronic enhancement. Digital imaging was used to analyse the chromosomal distribution of long CCA and AGG repeats. Our results suggest that long trinucleotide repeats occur in the normal human genome and that the size of individual repeat loci may be polymorphic.  相似文献   

16.
Recently an unstable trinucleotide CTG repeat, located within the 3' untranslated region of a gene on 19q13.3 was discovered in kindreds with myotonic dystrophy (DM). The age-of-onset/severity of DM shows a good correlation with CTG repeat size, and pedigrees and data reported to date have shown a striking trend toward amplification of the size of the CTG repeat during transmission from parent to child. The amplification has been accepted as the biological explanation for anticipation in the clinical severity observed in many families with DM. In this paper we report on 3 families where CTG amplification decreased during transmission from parent to child. In one case there was a gene conversion event, while in the remaining 2 there was a simpler reduction in the size of the repeat length. The changes appear to have been accompanied by a reduction in clinical severity in the child when compared to the parent. These observations are discussed in terms of their clinical implications and the biases that may exist in much of the reported data.  相似文献   

17.
305 preterm babies with birthweight below 1500 g were delivered at our centre between 1991 and 1994. Classification according to etiology shows that more than half (52.7%) of these deliveries had to be induced secondary to underlying fetal or maternal pathology. A more efficient tocolysis could have prevented up to one third of these deliveries (31.4%). The main cause of each preterm delivery was defined according to Whitfield's etiological classification. In decreasing order of frequency we found hypertensive disorders of pregnancy, multiple pregnancy, preterm premature rupture of membranes, preterm labour and vaginal bleeding in the third trimester. The majority of these deliveries (88.6%) were prenatal referrals, reflecting widespread regionalization of obstetric services in Switzerland. Nevertheless, 64 women (24.2%) with threatening preterm labour before the 32nd week of gestation had to be denied admission to our hospital because of shortage of neonatal intensive care beds, or had to be transferred from our hospital to another offering perinatal facilities during the study period (1991-1994). Acute lack of neonatal intensive care unit beds in Switzerland requires closer attention in the future.  相似文献   

18.
We report on a myotonic dystrophy (DM) family exhibiting instability of normal sized (CTG)n alleles in the DM kinase gene on the non-DM chromosome. At least two mutational events involving normal DM alleles must have occurred in this family; one was characterised as a 34-35 (CTG)n repeat mutation. These findings represent a dissociation between (CTG)n repeat instability and myotonic dystrophy. Furthermore, this family highlights genetic counselling issues relating to the pathogenicity of alleles at the upper end of the normal size range and the risk of further expansion into the disease range.  相似文献   

19.
OBJECTIVE: To determine whether women delivering their first child at age 35 years or older are at increased risk of adverse (non-genetic) pregnancy outcomes. DESIGN AND SETTING: A cross-sectional analytic study of singleton deliveries in Northern Sydney Area Health Service (NSAHS) hospitals. PARTICIPANTS: All women aged > or = 20 years delivering their first child between 1 January 1990 and 31 December 1991. MAIN OUTCOME MEASURES: Obstetric complications and procedures, type of delivery and neonatal outcomes. RESULTS: Compared with women aged 20-29 years, women delivering their first child at > or = 35 years were at increased risk of pre-existing maternal hypertension (adjusted odds ratio [OR], 3.5; 95% confidence interval [CI], 1.7-7.0), antepartum haemorrhage (adjusted OR, 2.4; 95% CI, 1.6-3.7), preterm delivery (33-36 weeks) (adjusted OR, 2.0; 95% CI, 1.5-2.8) and breech presentation (adjusted OR, 1.8; 95% CI, 1.3-2.4). Women aged > or = 35 years were also substantially more likely to have an operative delivery, induced labour and/or epidural anaesthesia. Neither these women nor their infants were at increased risk of pregnancy-induced hypertension, gestational diabetes, threatened premature labour, postpartum haemorrhage, very preterm delivery (< or = 32 weeks), perinatal death, low Apgar scores or the need for neonatal resuscitation. CONCLUSIONS: Women who delay the birth of their first child face some increased risks, but these risks, for the most part, are manageable in the context of modern obstetric care.  相似文献   

20.
To estimate the risk of repeat low birthweight deliveries among women whose first child was very low birthweight (less than 1500 g), a retrospective cohort of women who had their first and second children in Washington state between 1984 and 1991 was studied. After adjustment for potential confounding factors, a woman whose first infant was very low birthweight experienced an 11.5-fold increased risk of delivering a low birthweight (less than 2500 g) second infant (relative risk 11.5, 95% confidence interval 5.4 to 24.4). Women with a very low birthweight first infant also had a significantly increased risk of repeat very low birthweight infant (p < 0.0001). Women with a previous very low birthweight delivery are at increased risk of repeat low and very low birthweight infants. This high-risk group may benefit from education regarding recurrence risk and modification of factors associated with low birthweight, as well as good prenatal care.  相似文献   

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