OBJECTIVE: to discuss which elements, according to literature, are responsible for phenotypic discordance in monozygotic twins. METHODS: the data from a pair of female monozygotic twins were gathered. These data included their age at the time of the diagnosis, type of curve, Cobb angle of the deformity at the time of the initial consultation, dates of the start of treatment and the last follow-up, the apex of the curve and Cobb angle measured from radiological images in lateral view. RESULTS: child I: major lumbar curve to the left, with a Cobb angle of 17° between T11 and L4, and a thoracic curve to the right, with an angle of 14° between T5 and T11. The apices were at the L1-L2 disc and at the T8 vertebra, respectively. One year after the first consultation, there had been significant progression of the deformity, with the lumbar curve of 24° (T11-L4) and the thoracic curve of 23° (T5-T11). Child II: small thoracolumbar deformity to the right, which was confirmed radiographically with a Cobb angle of 18° between T9 and L3. The apex was located at the T12 vertebra. One year later, it was observed that the curve had increased, and the Cobb angle had become 40°. CONCLUSION: notwithstanding the evidence for a genetic origin for the development of scoliosis, it is accepted that other factors influence its manifestation and progression. In literature, the development of this disease has been explained in terms of the structural tissue deficiencies found in specific syndromes and conditions, asymmetrical growth of limbs and trunk, changes in sagittal configuration of the spine and factors relating to the environment, such as nutrition.
Scoliosis; Scoliosis; Diseases in twins
