Occipital horn syndrome
Incidence
Rare (about 100 cases reported). X-linked recessive. Males only.
Clinical Characteristics
It is a disorder of copper metabolism characterized by congenital cutis laxa, hyperextensible and hypermobile digits, and bony protuberances of the occiput. There are 3 inherited disorders known to be caused by genetic defects in copper metabolism: Wilson Disease, Menkes Disease and Occipital Horn Syndrome (OHS). OHS is considered to be a less severe allelic form of Menkes Disease. CLINICAL FEATURES: 1. Connective Tissue Dysmorphisms: 1. Cutaneous: 1. Cutis Laxa which is characterized by lax, soft, loose, wrinkled, hyperextensible skin especially on the face giving the patient an 'aged appearance'. 2. Skeletal findings: Major features are occipital horns (bony protuberance of the occiput), hyperextensible and hypermobile digits and limited extension of the elbows and knees. Other skeletal findings are carpal bone coalescences, delayed fontanelle closure, luxatio coxarum, osteomalacia, short clavicles and short stature. 3. Systemic 1. Respiratory: emphysema, laxity of vocal cords. 2. Cardiovascular: postural hypotension, vascular wall aneurysms and vascular stenoses. 3. Gastrointestinal: chronic diarrhea, inguinal hernias, multiple GI diverticula, hernias, and prolapses. 4. Genitourinary: bladder or ureteric diverticulae +/- spontaneous rupture. 2. Others: muscular weakness, also low normal intelligence to mild mental retardation. Caused by mutations in the ATPase, Cu++ transporting, alpha polypeptide gene (ATP7A).
Precipitants
none
Provocation Tests
none
Diagnostic Procedures
Decreased serum copper. Decreased ceruloplasmin. Diagnosis is made by finding decreased serum copper and ceruloplasmin, decreased lysyl oxidase activity in cultured cells and samples of skin. Also excess copper and increased copper accumulation in cultured fibroblasts. Skeletal X-Rays show occipital exostoses, shortened clavicles with thickened "hammerlike" distal ends. Voiding Cystouretrogram displays bladder or ureteric diverticulae. Angiograms may show arterial tortuosity, elongation, and stenosis.