A very rare autosomal recessive disorder, characterized by muscular weakness, multiple contractures, and orthopedic signs noted at birth or in early infancy. Cellular immunity can be involved.
Ullrich Scleroatonic Muscular Dystrophy; Ullrich Congenital Muscular Dystrophy; Scleroatonic Muscular Dystrophy; Scleroatonic Muscular Myopathy; Hypotonic Scleroatonic Muscular Dystrophy.
Autosomal recessive. Mutations of COL6A1, COL6A2, or COL6A3 on chromosome 21q22 lead to collagen VI deficiency.
Collagen VI is widely distributed throughout extracellular matrices including muscle, skin, tendon, cartilage, intervertebral discs, and adipose tissue. In skeletal muscle, collagen VI is particularly concentrated in and adjacent to basement membranes of myofibers. Collagen VI contributes to the properties of the local ECM microenvironment by forming a discrete network of beaded microfilaments which interacts with cell surface receptors and matrix molecules. Mutated collagen VI exhibits decreased adherence to their surroundings, which is the key mechanism of collagen VI-related myopathies.
Characterized by the association of nonspecific signs: generalized muscular weakness, contractures of multiple joints, and hyperextensibility in distal joints.
Onset at birth. Clinical features include congenital muscular dystrophy, neonatal muscle weakness with orthopedic signs (protrusion of calcaneus, clumsy gait, multiple neonatal proximal joint contractures, limited spine motion, hyperextensible distal joints, hip dislocation). Other signs are less frequent and can include hyperhidrosis and high-arched palate. Insufficient cellular immunity has been reported, which may contribute to the recurrent upper respiratory tract infections and pneumonia often observed. Intelligence and cardiac function are normal. Cyclosporin A treatment can slow progression.
Precautions before anesthesia
An anesthesiology consultation is highly recommended before elective surgery. The respiratory system must be carefully evaluated in the presence of muscular weakness (clinical, history, chest radiographs, CT, pulmonary function test, arterial blood gas analysis).
Careful intraoperative positioning is indicated because of joint contractures and spine rigidity. Direct laryngoscopy and tracheal intubation can be difficult because of temporomandibular contractures and palate abnormalities. Perioperative chest physiotherapy can be useful. There is no risk of malignant hyperthermia.
Succinylcholine is not contraindicated, but is best avoided because of muscular dystrophy and risk of hyperkalemia. Parasympatholytic drugs should be avoided in the presence of hyperhidrosis. If necessary, it is recommended to use glycopyrrolate or scopolamine.
Other conditions to be considered
☞Bethlem Myopathy: Also Collagen VI anomaly as above. This autosomal dominant disorder is caused by mutation in the COL6A1 gene, COL6A2, or the COL6A3 gene. The onset of age is most often in early infancy, progression may be slow, and most affected individuals may reach an advanced age. Moderate weakness ...