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PURPOSE: This study aims to describe the motives and considerations of couples carrying a structural chromosomal abnormality deciding on preimplantation genetic testing (PGT). METHODS: A qualitative exploratory study was conducted using semi-structured dyadic interviews with 13 couples (N = 26) carrying a structural chromosomal abnormality. All couples had an informative consultation in our PGT centre in the Netherlands. RESULTS: Almost all couples considered PGT or natural conception combined with prenatal diagnosis (PND) as the only two reproductive options. Among several considerations mentioned, the majority indicated that the wish to increase the chance of a successful pregnancy was the most important motive to opt for PGT. All couples who opted for PGT had first tried to conceive spontaneously and entered the PGT programme because of their adverse experiences during these attempts (infertility, recurrent miscarriage, termination of pregnancy, birth of an affected child). Couples that refrained from PGT were of advanced maternal age and expressed the long trajectory of PGT as the main reason to refrain. If conceiving spontaneously would not lead to an ongoing pregnancy, these couples also indicated that they would use PGT. CONCLUSION: This study shows that couples carrying a structural chromosomal abnormality consider PGT and spontaneous conception with PND as relevant reproductive options. They are looking for the option that is in their opinion the fastest way to establish a successful pregnancy. Information on the perceived pros and cons of PGT or spontaneous conception in these couples can help to optimize counselling and psychological support during the decision-making process.
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Aberraciones Cromosómicas , Heterocigoto , Motivación , Diagnóstico Preimplantación/psicología , Adulto , Femenino , Humanos , Masculino , Embarazo , Diagnóstico Prenatal , Historia Reproductiva , Encuestas y CuestionariosRESUMEN
STUDY QUESTION: Does PGD increase the risk on adverse cognitive and socio-emotional development? SUMMARY ANSWER: The cognitive and socio-emotional development in children born after PGD seems to be normal when compared to control groups. WHAT IS KNOWN ALREADY: A limited number of studies with small sample sizes indicate that the cognitive and socio-emotional development of (pre)school-aged children born after either PGD or PGS seem to be comparable to those of children born after IVF/ICSI and to naturally conceived (NC) children from the general population. STUDY DESIGN, SIZE, DURATION: For this study we invited 72 5-year-old PGD children, 128 5-year-old IVF/ICSI children and 108 5-year-old NC children from families with a genetic disorder. All children were invited between January 2014 and July 2016. PARTICIPANTS/MATERIALS, SETTING, METHODS: In total, 51 PGD children, 52 IVF/ICSI children and 35 NC children underwent neuropsychological testing (WPPSI-III-NL and AWMA). The children's parent(s) and teachers filled in questionnaires evaluating children's executive functioning (Behaviour Rating Inventory of Executive Functions; BRIEF) and socio-emotional development (Child Behaviour Checklist; CBCL and Caregiver-Teacher Report Form; C-TRF). MAIN RESULTS AND THE ROLE OF CHANCE: The mean full-scale intelligence quotient scores (P = 0.426) and performance on the AWMA Listening Span task (P = 0.873) and Spatial Span task (P = 0.458) were comparable between the three groups. Regarding socio-emotional development, the teachers' scores revealed more externalizing (P = 0.011) and total problem (P = 0.019) behaviour in PGD children than for IVF/ICSI children; both groups did not differ significantly from the NC children (P = 0.11). More children (13%) with an affected first-degree family member (mostly parent) were included in the PGD group than in the NC group. Scores in all groups fell within the normal population range and should be considered normal. LIMITATIONS, REASONS FOR CAUTION: The number of NC children from families with a genetic disorder was relatively small. Furthermore, the fathers' CBCL results were based on small samples. WIDER IMPLICATIONS OF THE FINDINGS: PGD children show levels of cognitive and socio-emotional development at 5 years that are within the normal range, despite the biopsy involved in PGD and the potential extra psychological burden associated with the presence of a genetic disorder in the family. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by ZonMw (70-71300-98-106). None of the authors have any competing interests to declare. TRIAL REGISTRATION NUMBER: NCT02149485.
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Desarrollo Infantil/fisiología , Cognición/fisiología , Función Ejecutiva/fisiología , Memoria a Corto Plazo/fisiología , Diagnóstico Preimplantación , Análisis de Varianza , Estudios de Casos y Controles , Preescolar , Femenino , Fertilización In Vitro/estadística & datos numéricos , Humanos , Pruebas de Inteligencia , Masculino , Pruebas de Memoria y Aprendizaje , Padres , Embarazo , Encuestas y CuestionariosRESUMEN
STUDY QUESTION: Do clinical characteristics of recurrent miscarriage couples with a chromosomal abnormality and who opt for PGD differ from couples that decline PGD after extensive genetic counselling? SUMMARY ANSWER: No differences in clinical characteristics are identified between recurrent miscarriage couples carrying a structural chromosomal abnormality who opt for PGD compared with those that decline PGD after extensive genetic counselling. WHAT IS KNOWN ALREADY: Couples who have experienced two or more miscarriages (recurrent miscarriage) are at increased recurrence risk if one of the partners carries a structural chromosomal abnormality. PGD can be offered to avoid (another) miscarriage or pregnancy termination when (invasive) prenatal diagnosis shows an abnormal result. To date, no reports are available that describe reproductive decision-making after genetic counselling on PGD in these specific couples. STUDY DESIGN, SIZE, DURATION: Retrospective cohort study of 294 couples carrying a structural chromosomal abnormality seeking genetic counselling on PGD between 1996 and 2012. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were recurrent miscarriage couples carrying a structural chromosomal abnormality. They had been referred for genetic counselling to the only national licensed PGD centre. Clinical characteristics analysed included couple associated characteristics, characteristics concerning reproductive history and external characteristics such as type of physician that referred the couple for genetic counselling and the clinical geneticist performing the counselling on PGD. MAIN RESULTS AND THE ROLE OF CHANCE: Of 294 couples referred for counselling on PGD, 26 were not accepted because they did not meet the criteria for IVF-PGD. The remaining cohort of 268 couples consisted of two-thirds female and one-third male carriers. Main PGD indications were reciprocal translocations (83.9%) and Robertsonian translocations (16.7%). Following genetic counselling, 76.9% of included couples chose PGD as their reproductive option, the others declined PGD. Reproductive choice is not influenced by sex of the translocation carrier (P = 0.499), type of chromosomal abnormality (P = 0.346), number of previous miscarriages (P = 0.882), history of termination of pregnancy (TOP) because of an unbalanced fetal karyotype (P = 0.800), referring physician (P = 0.208) or geneticist who performed the counselling (P = 0.410). LIMITATIONS, REASONS FOR CAUTION: This study only included recurrent miscarriage couples carrying a structural chromosomal abnormality, who were actually referred to a PGD clinic for genetic counselling. We lack information on couples who were not referred for PGD. Some of these patients may not have been informed on PGD at all, while others were not referred for counselling because they did not opt for PGD to start with. WIDER IMPLICATIONS OF THE FINDINGS: This study shows that reproductive choices in couples with recurrent miscarriage on the basis of a structural chromosomal abnormality are not influenced by characteristics of the couple itself, nor by their obstetric history or external characteristics. These findings suggest that a couples' intrinsic attitude towards PGD treatment is a major factor influencing their reproductive choice. Future research will focus on these personal motives that seem to push reproductive decision-making following genetic counselling in a given direction.
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Aborto Habitual/etiología , Trastornos de los Cromosomas/diagnóstico , Asesoramiento Genético , Heterocigoto , Aceptación de la Atención de Salud , Diagnóstico Preimplantación , Translocación Genética , Aborto Habitual/fisiopatología , Aborto Habitual/prevención & control , Centros Médicos Académicos , Adulto , Trastornos de los Cromosomas/genética , Trastornos de los Cromosomas/fisiopatología , Estudios de Cohortes , Composición Familiar , Femenino , Humanos , Masculino , Países Bajos , Servicio Ambulatorio en Hospital , Educación del Paciente como Asunto , Embarazo , Derivación y Consulta , Conducta Reproductiva , Historia Reproductiva , Estudios RetrospectivosRESUMEN
Array comparative genomic hybridization (aCGH) has led to an increased detection of causal chromosomal imbalances in individuals with congenital heart defects (CHD). The introduction of aCGH as a diagnostic tool in a clinical cardiogenetic setting entails numerous challenges. Based on our own experience as well as those of others described in the literature, we outline the state of the art and attempt to answer a number of outstanding questions such as the detection frequency of causal imbalances in different patient populations, the added value of higher-resolution arrays, and the existence of predictive factors in syndromic cases. We introduce a step-by-step approach for clinical interpretation of copy number variants (CNV) detected in CHD, which is primarily based on gene content and overlap with known chromosomal syndromes, rather than on CNV inheritance and size. Based on this algorithm, we have reclassified the detected aberrations in aCGH studies for their causality for syndromic and non-syndromic CHD. From this literature overview, supplemented with own investigations in a cohort of 46 sporadic patients with severe non-syndromic CHD, it seems clear that the frequency of causal CNVs in non-syndromic CHD populations is lower than that in syndromic CNV populations (3.6 vs. 19%). Moreover, causal CNVs in non-syndromic CHD mostly involve imbalances with a moderate effect size and reduced penetrance, whereas the majority of causal imbalances in syndromic CHD consistently affects human development and significantly reduces reproductive fitness.
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Anomalías Múltiples/genética , Variaciones en el Número de Copia de ADN , Cardiopatías Congénitas/genética , Animales , Aberraciones Cromosómicas , Cromosomas Humanos , Hibridación Genómica Comparativa/instrumentación , Hibridación Genómica Comparativa/métodos , Árboles de Decisión , Cardiopatías Congénitas/diagnóstico , Humanos , SíndromeRESUMEN
BACKGROUND: About 2-7% of familial cardiomyopathy cases are caused by a mutation in the gene encoding cardiac troponin I (TNNI3). The related clinical phenotype is usually severe with early onset. Here we report on all currently known mutations in the Dutch population and compared these with those described in literature. METHODS: TheTNNI3 gene was screened for mutations in all coding exons and flanking intronic sequences in a large cohort of cardiomyopathy patients. All Dutch index cases carrying a TNNI3 mutation that are described in this study underwent extensive cardiological evaluation and were listed by their postal codes. RESULTS: In 30 families, 14 different mutations were identified. Three TNNI3 mutations were found relatively frequently in both familial and non-familial cases of hypertrophic cardiomyopathy (HCM) or restrictive cardiomyopathy (RCM). Haplotype analysis showed that p.Arg145Trp and p.Ser166Phe are founder mutations in the Netherlands, while p.Glu209Ala is not. The majority of Dutch TNNI3 mutations were associated with a HCM phenotype. Mean age at diagnosis was 36.5 years. Mutations causing RCM occurred less frequently, but were identified in very young children with a poor prognosis. CONCLUSION: In line with previously published data, we found TNNI3 mutations to be rare and associated with early onset and severe clinical presentation.
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AIMS: Hypertrophic cardiomyopathy (HCM) is a frequent cause of sudden cardiac death (SCD) due to exercise-related ventricular arrhythmias (ERVA); however the pathological substrate is uncertain. The aim was to determine the prevalence of ERVA and their relation with fibrosis as determined by cardiac magnetic resonance imaging (CMR) in carriers of an HCM causing mutation. METHODS: We studied the prevalence and origin of ERVA and related these with fibrosis on CMR in a population of 31 HCM mutation carriers. RESULTS: ERVA occurred in seven patients (23%) who all showed evidence of fibrosis (100% ERVA(+) vs. 58% ERVA(-), p = 0.04). No ventricular tachycardia or ventricular fibrillation occurred. In patients with ERVA, the extent of fibrosis was significantly larger (8 ± 4% vs. 3 ± 4%, p = 0.02). ERVA originated from areas with a high extent of fibrosis or regions directly adjacent to these areas. CONCLUSIONS: ERVA in HCM mutation carriers arose from the area of fibrosis detected by CMR; ERVA seems closely related to cardiac fibrosis. Fibrosis as detected by CMR should be evaluated as an additional risk factor to further delineate risk of SCD in carriers of an HCM causing mutation.
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Background. With the improvement in genetic testing over time, double-heterozygous mutations are more often found by coincidence in families with hypertrophic cardiomyopathy (HCM). Double heterozygosity can be a cause of the wellknown clinical diversity within HCM families.Methods and results. We describe a family in which members carry either a single mutation or are double heterozygous for mutations in myosin heavy chain gene (MYH7) and cysteine and glycine-rich protein 3 (CSRP3). The described family emphasises the idea of a more severe clinical phenotype with double-heterozygous mutations. It also highlights the importance of cardiological screening where NT-proBNP may serve as an added diagnostic tool.Conclusion. With a more severe inexplicable phenotype of HCM within a family, one should consider the possibility of double-heterozygous mutations. This implies that in such families, even when one disease-causing mutation is found, all the family members still have an implication for cardiological screening parallel to extended genetic screening. (Neth Heart J 2009;17:458-63.).
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Subtelomeric chromosome aberrations: still a lot to learn.Cryptic subtelomeric chromosome aberrations are a significant cause of mental retardation (MR). More than 4000 patients have been investigated, and the mean overall prevalence of subtelomeric rearrangements has been found to be 5.2%. In order to contribute to knowledge on the clinical presentation of subtelomeric rearrangements, we retrospectively studied patients with unexplained MR who had been evaluated for subtelomeric abnormalities by different fluorescence in situ hybridization (FISH) techniques. Hundred and two patients had an unexplained combination of MR with dysmorphism, congenital anomalies, and/or a positive family history and were investigated by total subtelomeric (TS) FISH (89/102), or by total painting (TP) in an obligate carrier in the case of familial MR (13/102). In 59 additional patients, a sequence-specific FISH was performed on clinical indication. In the 102 patients studied by TS or TP, six pathogenic aberrations (5.9%) were found in addition to one polymorphism. In total, eight clinically significant subtelomeric aberrations were found in the 161 index patients; four of these eight aberrations were familial. We report on the clinical presentation of all patients with an aberration and review the relevant literature. Factors complicating the interpretation of subtelomeric rearrangements are discussed, such as the occurrence of variants, clinical variability, and limited knowledge of the phenotype.
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Aberraciones Cromosómicas , Discapacidad Intelectual/genética , Deleción Cromosómica , Trastornos de los Cromosomas/diagnóstico , Trastornos de los Cromosomas/genética , Femenino , Duplicación de Gen , Pruebas Genéticas , Humanos , Hibridación Fluorescente in Situ/métodos , Masculino , Fenotipo , Estudios Retrospectivos , Telómero/genética , Translocación Genética , TrisomíaRESUMEN
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.
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Deleción Cromosómica , Cromosomas Humanos Par 3/genética , Cromosomas Humanos Par 5/genética , Translocación Genética , Aberraciones Cromosómicas , Bandeo Cromosómico , Salud de la Familia , Femenino , Duplicación de Gen , Heterocigoto , Humanos , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , LinajeRESUMEN
Recently, the polyglutamine-binding protein 1 (PQBP1) gene was found to be mutated in five of 29 families studied with X-linked mental retardation (XLMR) linked to Xp. The reported mutations include duplications or deletions of AG dinucleotides in the fourth coding exon that resulted in shifts of the open reading frame. Three of the five families with mutations in this newly identified XLMR gene have been reported previously. We characterized the phenotypic and neuropsychological features in the two unpublished families with aberrations in PQBP1 and in a family reported 10 years ago. In total, seven patients diagnosed with aberrations in this gene were examined, including a newly identified patient at 18 months of age. Additionally, the features were compared to those reported in the literature of three other families, comprising MRXS3 (Sutherland-Haan syndrome) MRX55 and MRXS8 (Renpenning syndrome). Characteristics seen in these patients are microcephaly, lean body habitus, short stature, striking facial appearance with long narrow faces, upward slant of the eyes, malar hypoplasia, prognathism, high-arched palate and nasal speech. In addition, small testes and midline defects as anal atresia or imperforate anus, clefting of palate and/or uvula, iris coloboma and Tetralogy of Fallot are seen in several patients. These observations contribute to the phenotypic knowledge of patients with PQBP1 mutations and make this XLMR syndrome well recognizable to clinicians.
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Proteínas Portadoras/genética , Discapacidad Intelectual Ligada al Cromosoma X/genética , Mutación/genética , Proteínas Nucleares/genética , Adolescente , Adulto , Anciano , Niño , Preescolar , Proteínas de Unión al ADN , Familia , Femenino , Ligamiento Genético , Genotipo , Humanos , Lactante , Masculino , Persona de Mediana Edad , Linaje , Fenotipo , SíndromeRESUMEN
Chromosome analysis in a couple referred because of two spontaneous abortions showed a normal 46,XX karyotype in the 28-year-old female and an aberrant Y chromosome with an enlarged short arm in the 30-year-old male. Subsequent chromosome analysis showed that his 33-year-old brother was carrier of the same Y chromosome aberration. Further characterization of the aberrant Y chromosome with FISH using probes specific for chromosome bands Yp11.32, Yq11.2, the centromere and the subtelomeric region of the p-arm of the Y chromosome showed that chromosome band Yq11.2 was duplicated and inserted in the p-arm of the Y chromosome. Combining the results of the analysis of GTG-banded chromosomes and of the FISH analysis we conclude that both patients have a 46,X,ins dup(Y)(pter --> p11.23::q12 --> q11.1::p11.23 -->) karyotype. The clinical and cytogenetical findings are reported and discussed.
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Cromosomas Humanos Y , Translocación Genética , Aborto Habitual , Adulto , Aberraciones Cromosómicas , Bandeo Cromosómico , Femenino , Duplicación de Gen , Humanos , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , Fenotipo , EmbarazoRESUMEN
OBJECTIVES: To characterize changes in myometrial contractile proteins and myosin heavy chain (MHC) isoforms during ovine fetal and neonatal development and after pregnancy. We hypothesized that ovine myometrium demonstrates progressive cellular differentiation and maturation which begins in utero and extends into the postnatal period, and that pregnancy causes further cellular alterations. METHODS: Myometrium was obtained from female fetal (72- to 140-days of gestation, n = 19; term = approximately 145 days), postnatal (1 day to 3 months, n = 25), and parous noncycling nonpregnant (n = 9) sheep to measure total and soluble proteins, actin, MHC, and MHC isoforms. Contractile proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and expression of 200-kD MHC isoforms were determined with Western immunoblots. RESULTS: The contents of total and soluble proteins and actin and total myosin gradually increase (P <.003) during ovine development. Although the contribution of smooth-muscle 204-kD MHC increased (P <.001) from 23 +/- 8% of total MHC at <100 days of gestation to 75 +/- 2% 3 to 4 months postnatally, the 200-kD species fell proportionately. Before birth, MHC-B, a fetal isoform, is the predominant 200-kD protein; postnatally, it is replaced by SM2, demonstrating a switch from a synthetic to a mature contractile smooth-muscle phenotype. Pregnancy is associated with further increases in actin contents and redistribution of the contents of the 204-kD and SM2 MHC isoforms. CONCLUSIONS: Although the fetal and postnatal uterus has no known functional demand, ovine myometrial differentiation and maturation begin in the midtrimester and continue throughout the postnatal period. Thus, changes in smooth-muscle phenotype occur prenatally, as evidenced by a switch from MHC-B to SM2, which may signal completion of organ development and preparation for adult function. Pregnancy results in further modifications in myometrial proteins.
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Desarrollo de Músculos , Músculo Liso/crecimiento & desarrollo , Paridad , Útero/crecimiento & desarrollo , Actinas/análisis , Animales , Western Blotting , Electroforesis en Gel de Poliacrilamida , Femenino , Proteínas Musculares/análisis , Músculo Liso/química , Músculo Liso/embriología , Cadenas Pesadas de Miosina/análisis , Miosinas/análisis , Fenotipo , Embarazo , Ovinos , Útero/química , Útero/embriologíaRESUMEN
Maturation rates of vascular and visceral smooth muscle (SM) during ovine development were compared by quantifying contractile protein, myosin heavy chain (MHC) isoform contents, and contractile properties of aortas and bladders from female fetal (n = 19) and postnatal (n = 21) sheep. Actin, myosin, and protein contents rose progressively throughout development in both tissues (P = 0.003); however, expression patterns differed. During the last trimester, i. e., 101-130 days (term approximately 145 days), bladder actin and MHC contents were approximately twofold greater (P < 0.04) than those in the aorta. Although the fractional content of 204-kDa SM1 MHC in the bladder decreased from 74 +/- 3% at midgestation to 48 +/- 2% 3 mo postnatal, the aorta exhibited an increase from 30 +/- 2% to 65 +/- 2%. Bladder MHC (MHC-B) migrating at 200 kDa contained only SM2 throughout development. In contrast, 200-kDa MHC in the aorta was predominantly nonmuscle MHC-B at midgestation, which was gradually replaced by SM2 as development progressed. Along with its early expression of SM2, bladder muscle obtained maximal stress generating capacity (1.7 x 10(5) N/m(2)) by term gestation, whereas the aorta exhibited no contractions until after birth. We conclude that whereas aortic SM maturation is delayed until after birth, bladder SM matures biochemically and functionally during prenatal development, thus supporting early requirements for micturition.
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Desarrollo de Músculos , Músculo Liso Vascular/crecimiento & desarrollo , Músculo Liso/crecimiento & desarrollo , Vejiga Urinaria/crecimiento & desarrollo , Actinas/análisis , Animales , Aorta/química , Aorta/crecimiento & desarrollo , Proteínas Contráctiles/análisis , Femenino , Contracción Isométrica , Proteínas Musculares/análisis , Músculo Liso/química , Músculo Liso/embriología , Músculo Liso Vascular/química , Músculo Liso Vascular/embriología , Cadenas Pesadas de Miosina/análisis , Cadenas Ligeras de Miosina/metabolismo , Quinasa de Cadena Ligera de Miosina/metabolismo , Miosinas/análisis , Fosforilación , Ovinos , Vejiga Urinaria/química , Vejiga Urinaria/embriologíaRESUMEN
Two patients with a trisomy 7p are reported. Both were assessed by facial dysmorphism and congenital anomalies. In one of the patients trisomy 7p was a de novo event, in the other patient unbalanced inheritance of a parental translocation caused trisomy 7p. Developmental delay was severe in both. Our 2 cases are compared with patients reported in literature.
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Anomalías Múltiples/genética , Cromosomas Humanos Par 7 , Trisomía , Preescolar , Análisis Citogenético , Femenino , Humanos , Recién Nacido , Cariotipificación , MasculinoRESUMEN
In fetal sheep, umbilical responsiveness to ANG II exceeds systemic vascular responsiveness. Fetal systemic vascular smooth muscle (VSM) exhibits an immature phenotype with decreased contractile protein contents, low 200-kDa myosin heavy chain (MHC) SM2, and significant nonmuscle MHC-B expression, whereas umbilical VSM phenotype is incompletely described. We tested the hypothesis that differences in vascular responsiveness could reflect dissimilarities in VSM phenotype. Actin, MHC, MHC isoforms, and active stresses were compared in strips of femoral arteries and aorta from near-term fetal (n = 12) and adult (n = 12) sheep to those in external and intra-abdominal umbilical arteries. Actin contents in fetal femoral artery and aorta were less (P = 0.006) than in external umbilical artery (7.37 +/- 1.4 and 7.53 +/- 0.7 vs. 21.6 +/- 2.2 microg/mg wet wt, respectively) as were MHC contents (3.17 +/- 0.4 and 2.84 +/- 0. 3 vs. 7.16 +/- 0.7, respectively). Whereas 204- and 200-kDa MHC were expressed equally in fetal systemic arteries, umbilical and adult arteries predominantly expressed the 204-kDa isoform (SM1); only fetal systemic VSM expressed MHC-B. Fetal systemic artery stresses and myosin light chain phosphorylation were less than those in umbilical and adult arteries (P < 0.001). Compared with umbilical and adult arteries, fetal systemic VSM is biochemically and functionally immature and thus umbilical VSM demonstrates precocious maturation resembling adult VSM in protein expression and function.