Phenotype variability of dystonia in monozygotic twins

Abstract

Sirs: Suggestions that dystonia may be initiated by a peripheral trauma date from the nineteenth century [1]. However, the demonstration of a direct causative link has so far been lacking. Case reports have shown that the clinical presentation of posttraumatic dystonia differs substantially from that of primary torsion dystonia [2, 3]. Family 2 of the Gemelli dystonia registry present a case of autosomal dominant transmission of a homogeneous cervical dystonia phenotype linked to a still unmapped gene [4]. We studied two twin sisters (family members III:6 and III:8; Fig.1) who shared with all other family members the homogeneous phenotype of adult-onset craniocervical dystonia. They were identical twin sisters, born at term by uncomplicated vaginal delivery. Neither of them received any kind of medication known to cause or to affect dystonia or were reported to have suffered any trauma. Life events of the twins were reconstructed in detail by collecting all the available information. Past medical and personal data of the twin sisters were collected from each family member by cross-referencing hospital records, interviews of relatives, and any available photographs and videos (Table 1). DNA was extracted from whole blood according to standard methods. Analysis of GT polymorphisms was carried out by PCR and acrylamide gel electrophoresis. The polymorphisms and their localization were: HD CAG (4p), D4S392 (4q), D4S1534 (4q) SCA1 CAG (6p), D9S60 (9q), DRPLA CAG (12p), D12S1328 (12q), D14S52 (14q), D16S283 (16p), D18S62 (18p), D19S215 (19p). Monozygosity of the twin sisters was confirmed by observing identical alleles for these highly polymorphic markers. In addition, the parental alleles were reconstructed on the basis of the four sibs genotypes. For six markers all the four parental alleles were segregating, while for two markers only three different parental alleles were found. The remaining three markers were not informative. The conditioned probability of the twins being dizygotic, given the results obtained, was 1.1 × 10–4 (considering an a priori probability of dizygotic and monozygotic twins in the white population of 0.64 and 0.36, respectively). Twin 1 (III:6) was seen at the Movement Disorders Clinic of Gemelli Hospital. She was the firstborn and was breast fed; her early development was reported to have been normal. At the age of 6 years she and her twin were asked by their parents to help in farm work. As is customary among women in that rural area, twin 1 started carrying heavy bags, such as bales and pitchers, on top of her head. She had menarche at the age of 14 years. At the age of 23 she married, moved to Rome, and stopped working in agriculture. At the age of 24 she had her first uncomplicated pregnancy followed by a natural delivery. At the age of 38 a second pregnancy ended in a miscarriage. Menopause occurred at 48 years. She suffered from familial goiter and gallbladder stones. At the age of 55 the patient moved back to her village and resumed farm work; again she carried heavy weights on her head when working as a farmer. She did so for a total time of 26 years (from 6 to 23 and from 55 to 65 years of age). At the age of 65 years she reported the onset of pain and tension in the posterior muscles of the neck; a few months later, she developed retrocollis and stopped carrying weights on her head. Dystonia progressed rapidly. At the age of 66 axial dystonia (with retrocollis, irregular head tremor, and trunk involvement) was associated with severe blepharospasm, tremulous adductor laryngeal dystonia, jaw-opening movements, and dystonic posturing of the upper limbs. Typical sensory tricks LETTER TO THE EDITORS J Neurol (2000) 247 :148–150 © Steinkopff Verlag 2000

DOI: 10.1007/s004150050035

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@article{Albanese2000PhenotypeVO, title={Phenotype variability of dystonia in monozygotic twins}, author={Anthony Albanese and A. R. Bentivoglio and Nick Del Grosso and Emanuele Cassetta and Marina Frontali and Enza Maria Valente and Pietro Attilio Tonali}, journal={Journal of Neurology}, year={2000}, volume={247}, pages={148-150} }