ID/CC A 37-year-old man presents with dark, blackened spots in his sclera and ear cartilage as well as back pain and restriction of motion with pain and .swelling of both knee joints.
HPI Directed questioning reveals that his urine turns black if left standing.
Labs UA: elevated urine homogentisic acid (causes urine to darken upon standing or with addition of alkaline substances).
Imaging XR: calcification in cartilage of knee menisci and wrist; premature arthritic changes.
Discussion Also called ochronosis, alkaptonuria is an autosomal-recessive disorder of tyrosine metabolism characterized by the absence of homogentisate oxidase due to a defective gene on chromosome 3 with accumulation of homogentisic acid in cartilage, giving a dark blue discoloration to the tissues and leading to degenerative joint disease.
ID/CC An 11-year-old white female is brought to the ER by her parents because of fever, difficulty breathing, and a productive cough with greenish sputum.
HPI Her parents are of northern European descent. She has a history of recurrent UTIs and foul-smelling diarrhea since infancy.
PE VS: tachycardia; tachypnea (RR 45). PE: mild cyanosis; malnour-ishment; nasal polyps; hyperresonance to lung percussion with barrel-shaped chest: scattered rales; hepatomegaly.
Labs High sodium and chloride concentrations in sweat test;
Pseudomonas aeruginosa, Haemophilus influenzae and Staphylococcus aureus in sputum culture. PFTs: increased RV/TLC ratio. Increased fecal fat. ABGs: hypoxemia; hypercapnia.
Imaging CXR: few dilated bronchi (BRONCHIECTASIS) filled with mucus;
emphysema; XR, paranasal sinuses: opacification of sinuses.
Atrophic pancreas with almost complete disruption of acini and replacement of exocrine pancreas with fibrous tissue and fat; mucous plugging of canaliculi.
Treatment Antibiotics, low-fat diet, and supportive measures; recombinant human DNase (cleaves extracellular DNA from neutrophils in sputum); inhaled amiloride, nasal corticosteroids, systemic corticosteroids, decongestants; consider lung transplant.
Discussion Cystic fibrosis is an autosomal-recessive disease that is due to a mutation in the long arm of chromosome 7 (band q31) in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. If CFTR function is deficient, chloride and water transport is slowed and secretions are inspissated.
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