Schwartz-Jampel syndrome: clinical, electromyographic and genetic studies.

Two sisters aged 9 and 7 from consanguineous parents are described. Both of them develop myotonia, muscular weakness as early as the first year after birth. At the age 3-4 a disturbed gait appeared due to knee joint contractures and limited joint movements. The children display facial dysmorphism (a small forehead, a flat base of the nose, a receding chin, an irregular order of the teeth, low-set ears, a high-arched palate, low hair-line), kyphoscoliosis, pigeon breast, severe contractures of the knee and elbow joint and foot deformities. The elder sister cannot walk. Hirsutism of all four limbs is found as well as sparse subcutaneous tissue. Muscles are stiff and firm. Tendon reflexes of the lower limbs are absent. Muscle enzymes show slightly increased values. The EMG needle examination in both sisters was abnormal. Spontaneous, continuous, high-frequency, low-voltage electrical discharges were observed in all distal and proximal muscles of the hands and legs. Some of them have a typical myotonic pattern. The MCV and the SCV was within the normal range. Both parents of our patients, their sister aged 4, as well as their grandparents showed no clinical and EMG abnormalities. All these data allow authors to affirm the diagnosis chondrodystrophic myotonia.