Risk factors |
Dominant autosomal disease |
CTG expansion at 19q13.33 |
Anticipation2 |
Organic systems |
Muscular |
Variations in fibre size, atrophy of type 1 fibres |
Ringed fibres, increased central nuclei, nuclear chains21 |
Nervous |
General and focal cerebral atrophy, progressive ventricular dilatation, white matter lesions22–25 |
Reduced cortical glucose utilisation26 |
Reduced blood flow in fronto-temporal regions bilaterally25–27 |
Central motor control involved28 |
Auricular |
Bilateral high tone hearing loss29 |
Ocular |
Early cataracts (78–97%), frequent symmetrical ptosis2,30 |
Retinopathy, blepharitis, corneal lesions2 |
Digestive |
Locking of the jaw, weakness of the palate and decreased chewing ability2,31 |
Smooth muscle dysfunction affecting all parts of the GI tract32 |
Slow oesophageal transit and gastric emptying33 |
Small intestine and colonic dysmotility,33 colonic pseudo-obstruction |
Bile acid malabsorption, high incidence of gall bladder stones33 |
Anal sphincter weakness and myotonia34 |
Respiratory |
Alveolar hypoventilation, marked hypercapnia35 |
Respiratory muscle weakness35 and myotonia36 |
Restrictive respiratory disease (58%)35 |
Central37 and obstructive sleep apnoea38 |
Cardiovascular |
Extensive involvement of cardiac conducting tissue with fatty infiltration, fibrosis and degenerative change39 |
Abnormal ECG (65%)40–42 |
AV conduction disturbances, heart block, atrial flutter and fibrillation39,43 |
Ventricular tachy/brady-arrhythmias42 |
Hypotension44 |
Sudden death (8–30%)39,43,45 (2nd cause of death)45 |
Endocrine |
Hypogonadism, testicular atrophy (60–90%)2 |
Hyperinsulinaemia, diabetes2 |
HPA axis disturbance, abnormal diurnal rhythm of cortisol46 |
Growth hormone secretion disturbance,47 hyperleptinaemia48 |
Increased interleukin 6 and tumour necrosis factor α49 |
Decreased DHEA and DHEA sulphate50 |
Urinary |
Urgency, frequency and stress incontinence51 |
Reproductive |
Uterus; incoordinate contraction in labour and in vivo2 |
Skeletal |
Talipes (CF)2 |
Cutaneous |
Premature balding2 |