Variantes citogenéticas en pacientes con síndrome de Turner diagnosticadas en un hospital de tercer nivel de atención en Ecuador / Cytogenetic variants in patients with Turner syndrome diagnosed in a third level care hospital in Ecuador

Resumen Introducción: El Síndrome de Turner (ST) es una alteración cromosómica sexual causada por la ausencia parcial o completa del cromosoma X, además de mosaicismos y otras alteraciones estructurales del cromosoma X o Y; está presente en 1 de 2500 nacidas vivas. Objetivo: Describir las variantes citogenéticas de pacientes con síndrome de Turner y evaluar su asociación con el fenotipo de presentación y la edad del diagnóstico. Método: Estudio retrospectivo de corte transversal de una serie de 82 casos de síndrome de Turner. Los cariotipos fueron realizados utilizando el medio RPMI-1640; las preparaciones de cromosomas se obtuvieron utilizando técnicas estándar y se analizaron mediante bandas GTG con una resolución de 400-450 bandas, donde se contó con 20-50 metafases para reducir la probabilidad de no detección de mosaicismo. Resultados: 45 (55.6%) fueron diagnosticadas, con monosomía clásica del cromosoma X, mientras 29 (35,8%) mostraron anomalías estructurales del cromosoma X y 7 (8,6%) se asociaron a mosaicos numéricos del cromosoma X. Solo 21 (26%) pacientes fueron diagnosticadas por debajo de los 12 años, mientras el resto 60 (74%) se detectaron entre la adolescencia y la adultez. La baja estatura fue una característica universal en todos los grupos de estudio. Conclusiones: Las fórmulas cromosómicas en el síndrome de Turner pueden ser muy variadas y tener diversas implicaciones en el fenotipo; se destaca la baja talla como un criterio clínico relevante en la sospecha clínica.

Abstract Introduction: Turner Syndrome (TS) is a sexual chromosomal alteration caused by the partial or complete absence of the X chromosome, in addition to mosaicisms and other structural alterations of the X or Y chromosome; It is present in 1 in 2,500 live births. Objective: To describe the cytogenetic variants of Turner syndrome patients and to evaluate their association with the phenotype at presentation and age at diagnosis. Methods: Retrospective cross-sectional study of a series of 82 cases of Turner syndrome. Karyotypes were performed using RPMI-1640 medium; Chromosome preparations were obtained using standard techniques and analyzed by GTG banding with a resolution of 400-450 bands where 20-50 metaphases were counted to reduce the probability of missing mosaicism. Results: 45 (55.6%) were diagnosed with classic monosomy of the X chromosome, while 29 (35.8%) showed structural abnormalities of the X chromosome and 7 (8.6%) were associated with numerical mosaics of the X chromosome. Only 21 (26%) patients were diagnosed under 12 years of age, while the rest 60 (74%) were detected between adolescence and adulthood. Short stature was a universal characteristic in all study groups. Conclusions: The chromosomal formulas in Turner syndrome can be variable and have different implications in the phenotype; short stature stands out as a relevant clinical criterion in clinical suspicion.

X chromosome gene dosage as a determinant of congenital malformations and of age-related comorbidity risk in patients with Turner syndrome, from childhood to early adulthood.

Objective Turner Syndrome is associated with several phenotypic conditions associated with a higher risk of subsequent comorbidity. We aimed to evaluate the prevalence of congenital malformations and the occurrence of age-related comorbid conditions and to determine whether the frequencies of congenital and acquired conditions depend on X chromosome gene dosage, as a function of karyotype subgroup. Design and methods This national retrospective observational cohort study includes 1501 patients. We evaluated the prevalence of congenital malformations and the cumulative incidence of subsequent specific comorbidities at five-year intervals, from the ages of 10 to 30 years, with stratification by karyotype subgroup: 45,X (n = 549), 45,X/46,isoXq (n = 280), 46,X,r(X)/46,XX (n = 106), 45,X/46,XX (n = 221), presence of Y (n = 87). Results Median age was 9.4 (3.7-13.7) years at first evaluation and 16.8 (11.2-21.4) years at last evaluation. Congenital heart (18.9%) malformations were more frequent in 45,X patients, and congenital renal (17.2%) malformations were more frequent in 45,X, 45,X/46,isoXq and 46,X,r(X)/46,XX patients than in those with 45,X/46,XX mosaicism or a Y chromosome (P < 0.0001). The cumulative incidence of subsequent acquired conditions, such as thyroid disease, hearing loss, overweight/obesity, dyslipidemia and, to a lesser extent, celiac disease, glucose intolerance/type 2 diabetes, hypertension and liver dysfunction increased with age, but less markedly for patients with mosaicism than for those with other karyotypes. Patients with a ring chromosome were more prone to metabolic disorders. Conclusion These data suggest that X gene chromosome dosage, particularly for Xp genes, contributes to the risk of developing comorbidities.

Shifting syndromes: Sex chromosome variations and intersex classifications.

The 2006 'Consensus statement on management of intersex disorders' recommended moving to a new classification of intersex variations, framed in terms of 'disorders of sex development' or DSD. Part of the rationale for this change was to move away from associations with gender, and to increase clarity by grounding the classification system in genetics. While the medical community has largely accepted the move, some individuals from intersex activist communities have condemned it. In addition, people both inside and outside the medical community have disagreed about what should be covered by the classification system, in particular whether sex chromosome variations and the related diagnoses of Turner and Klinefelter's syndromes should be included. This article explores initial descriptions of Turner and Klinefelter's syndromes and their subsequent inclusion in intersex classifications, which were increasingly grounded in scientific understandings of sex chromosomes that emerged in the 1950s. The article questions the current drive to stabilize and 'sort out' intersex classifications through a grounding in genetics. Alternative social and historical definitions of intersex - such as those proposed by the intersex activists - have the potential to do more justice to the lived experience of those affected by such classifications and their consequences.

Advances in laboratory evaluation of Turner syndrome and its variants: beyond cytogenetics studies.

Turner syndrome is a clinically defined phenotype that is characterized by partial or complete X chromosome monosomy. A host of cytogenetic aberrations and mosaicism have been associated with this syndrome. Some individuals, Turner syndrome variants, have cytogenetic findings consistent with Turner syndrome, but exhibit atypical clinical phenotypes. Recently, several molecular tests have been presented to allow for the refined clinical study of Turner syndrome and its variants.

[Current aspects of Turner syndrome]. / Actualité du syndrome de Turner.

Recent progress in the clinical, genetic and therapeutic knowledges of Turner's syndrome are presented. The quality of life of Turner's syndrome can be much improved by early treatment with recombinant human growth hormone which significantly increases the patient's final height, and appropriate oestrogenic therapy at pubertal and adult ages. However, this requires an early diagnosis. Consequently, a karyotype must be performed in every girl with delayed growth, even in the absence of clinical features of the Turner's syndrome.

Ullrich-Turner syndrome with a small ring X chromosome and presence of mental retardation.

Since some patients with Ullrich-Turner syndrome (UTS) have mental retardation, we reviewed our experience to look for a high-risk subgroup. Among 190 UTS and gonadal dysgenesis patients with X chromosome abnormalities, 12 had mental retardation. All of the six (100%) with a small ring X were educable (EMI) or trainable mentally impaired (TMI) with more severe delay than expected in UTS. Among the 184 with other X abnormalities, only 6 had similar delays (2 from postnatal catastrophes), for a frequency of 3.3% mental retardation among those without a small ring X; only 2.2% of these had unexplained mental retardation. Polymerase chain reaction studies showed no Y-derived material in the 2 patients who were evaluated, and in situ hybridization confirmed X origin of the ring in the 6 subjects who were evaluated. We describe the phenotype of the 6 individuals with a small ring X, and an additional 2 patients with a small ring X who were identified outside the survey. The subjects with a small ring X comprised a clinically distinct subgroup which had EMI/TMI and shorter stature than expected in UTS. Seizures and a head circumference less than 10th centile were observed in half of the patients with a small ring X, and strabismus, epicanthus, and single palmar creases were present in more than half. A "triangular" face in childhood, pigmentary dysplasia, sacral dimple, and heart defects were also common. Neck webbing appeared to be less frequent than in 45,X. We hypothesize that the high risk of mental retardation in this form of the UTS results from lack of lyonization of the ring X due to loss of the X inactivation center. Excluding those with a small ring X, mental retardation is not significantly increased in patients with UTS.

Cytogenetic findings in a consecutive series of 478 patients with Turner syndrome. The Leuven experience 1965-1989.

In this report, we present the cytogenetic findings in 478 patients with Turner syndrome diagnosed in Leuven in the period 1965-1989. The karyotypic anomalies are classified into seven groups: 1) classic, 45,X karyotype (52.1%); 2) mosaic 45,X/46,XX (10.9%); 3) mosaic 45,X/47,XXX and other "super-female" cell lines (4.6%); 4) isochromosomes i(Xq) and i(Xp) (16.1%); 5) ring chromosomes r(X) (4.4%); 6) other structural aberrations of the X chromosome (7.7%); and finally 7) mosaic 45,X/46,XY patients (4%). The most pertinent chromosomal findings are briefly discussed and compared with previous reported surveys on subject.

Turner syndrome: the Leuven experience (1965-1989) in 478 patients. I. Patient's age at the time of diagnosis in relation to chromosomal findings.

Within the past 25 years 478 patients with Turner syndrome have been diagnosed in the Leuven Centre for Human Genetics. After exclusion of 36 lost pregnancies, mostly first trimester spontaneous abortions, almost 20 per cent of the remaining 442 Turner syndrome patients have been early detected, i.e. before the age of two years. Moreover, a high prevalence of classic 45,X karyotype over other karyotypes was observed in this age group. The high mortality of prenatally diagnosed Turner syndrome fetuses is discussed here in view of the most common associated congenital malformations.