BUZZWORD
DIAGNOSIS
WHY IT APPEARS
PAGE
Phenylketonuria
Phenylacetate and other phenylketones in sweat/urine
Maple syrup / burnt sugar urine
MSUD
Branched-chain α-ketoacids (sotolone)
Urine darkens on standing
Alkaptonuria
Homogentisic acid oxidizes in air
Port-wine urine + abdominal pain
Acute intermittent porphyria
PBG oxidizes to dark porphobilin
Tay-Sachs, Niemann-Pick (also CRAO)
Lipid-swollen ganglion cells whiten the retina; fovea has no ganglion cells
"Crumpled tissue paper" macrophages
Gaucher
Glucocerebroside fibrils in lysosomes
Lead poisoning (also thalassemia)
Lead blocks pyrimidine 5′-nucleotidase → ribosomal RNA clumps
Cystinuria
Insoluble cystine precipitates
Mitochondrial myopathy (MERRF)
Subsarcolemmal clumps of abnormal mitochondria
Duchenne muscular dystrophy
Proximal pelvic girdle weakness
Osteogenesis imperfecta
Thin type I collagen sclera shows the choroid
Menkes
Copper-dependent enzymes (lysyl oxidase) fail
Lens up and out vs down and in
Marfan vs homocystinuria
Fibrillin zonules vs homocysteine-damaged zonules
Lesch-Nyhan
Purine salvage failure (HGPRT)
Angelman
Loss of maternal UBE3A
Insatiable hunger after neonatal hypotonia
Prader-Willi
Loss of paternal 15q11–q13 (hypothalamic)
3 Ds (diarrhea, dermatitis, dementia)
Pellagra (niacin)
↓ NAD⁺ in high-turnover tissues
Corkscrew hairs, bleeding gums
Scurvy
Unhydroxylated, weak collagen
G6PD deficiency
Denatured Hb removed by splenic macrophages
Fruity breath, Kussmaul breathing
DKA
Acetone exhaled; respiratory compensation of acidosis