2025 – PAGE 359 – INBORN ERRORS OF METABOLISM & MISCELLANEOUS METABOLIC DISORDERS
FABRY DISEASE (AKA FABRY’S DISEASE)
Fabry disease (AKA Fabry’s disease) findings include opacities of the eye, vascular disease of the kidney, heart or brain, and reddish-purple skin lesions (angiokeratomas).
PEARL: There is no organomegaly. Though not included in the HuNiTaG mnemonic, it’s a very common lysosomal disorder, so it’s likely high yield.
MNEMONIC: Imagine Kanye West wearing his famous WHITE SUNGLASSES (opacities) and a PURPLE-colored suit (skin) made of ROUGH (rash) FABRYc.
NIEMANN-PICK DISEASE
Niemann-Pick disease is a sphingomyelinase deficiency that results in accumulation of sphingomyelin in macrophages within the liver and lungs. Patients have neurologic problems, hepatosplenomegaly, and a cherry red spot on the macula.
PEARL: If you are given a patient with a cherry red spot on the macula and hepatomegaly, this is your answer! Tay-Sachs does not have organomegaly!
MNEMONIC: Imagine a mall socialite who is stumbling around Niemann Marcus taking shots of tequila with cherries on top. Niemann Marcus = niemann pick, stumbling around = neurological deficits, shots of tequila = hepatosplenomegaly, cherries on top = cherry red spots
MISCELLANEOUS DISORDERS AND PEARLS
HYPOGLYCEMIA DIFFERENTIAL
When the cause of hypoglycemia is not clear, consider getting other labs such as urine ketones, reducing substances, urine organic acids, and serum lactic acid.
- INFANT OF A DIABETIC MOTHER (IDM): See next topic.
- HYPERINSULINISM: Look for a BIG BABY in whom the hypoglycemia gets better with glucagon, but only transiently. May be present in an infant of a diabetic mother. All growth parameters are likely to be high (around the 95th percentile). Treat with DIAZOXIDE, which decreases insulin production and increases cortisol release. Calcium channel blockers do not work in children with hypoglycemia due to hyperinsulinism.
- ADRENAL INSUFFICIENCY: Hypoglycemia + Ketones ± Electrolyte abnormalities
- HEREDITARY FRUCTOSE INTOLERANCE: Hypoglycemia + Ketones + Emesis after a meal containing fructose.
- ORGANIC ACIDEMIAS: ALL LABS ARE MESSED UP! + EARLY symptoms (by DOL 2)
- FATTY ACID METABOLISM DEFECT: Hypoglycemia WITHOUT Ketosis!
- GSD I (von Gierke): Hypoglycemia + Ketones + Lactic Acidosis + Elevated Uric Acid + Normal Ammonia.
- GALACTOSEMIA: Hypoglycemia + Hepatomegaly + Non-glucose reducing substances in the urine + FTT + Early presentation due to lactose in mom’s milk.