Probenicid is co-administered with penicillin to prolong its half-life through decreased renal tubular secretion when higher blood levels are warranted.

Risk of retinopathy is greatest with chloroquine and does not exist for quinacrine

Postzygotic activating mutation in GNAS is associated with all of the following except:

Options:
A- CALM (Café-au-lait macules)
B- Precocious puberty
C- Hypothyroidism (hyperthyroidism)
D- Polycystic fibrous dysplasia
E- FSH & LH are low
Step 1: Understand the key concept – GNAS mutation
• GNAS gene → encodes the Gs alpha subunit → activates cAMP pathway.
• Postzygotic mutation → leads to mosaicism.
• Classic disorder: McCune-Albright syndrome (MAS).

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Step 2: Recall the clinical features of MAS

McCune-Albright syndrome triad:
1. Café-au-lait macules (CALM) → often “coast of Maine” irregular borders. ✅
2. Fibrous dysplasia of bone → can be polyostotic (many bones). ✅
3. Endocrine hyperfunction (due to constitutive Gs activation):
• Precocious puberty (most common in girls). ✅
• Hyperthyroidism ✅
• Growth hormone excess ✅
• Cushing syndrome sometimes
• FSH & LH are normal or elevated if gonadotropin-dependent, but in MAS, precocious puberty is usually gonadotropin-independent, so FSH & LH are low ✅

Wolf’s Isotopic Response

👉 Definition: A new, unrelated skin disease appears exactly at the site of a healed dermatosis.

👉 Classic trigger: Most often after healed herpes zoster scars.

👉 Second diseases reported (remember “Great King Loves Smart And Loyal Tough Warriors Make Strong Brave Soldiers”):
• Granuloma annulare
• Kaposi sarcoma
• Leukemia cutis
• Sarcoidosis
• Acne
• Lichen planus
• Tinea
• Warts (verruca plana)
• Molluscum contagiosum
• Squamous cell carcinoma
• Basal cell carcinoma
• Skin cysts (epidermoid)

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So just remember:
“After Zoster heals, the Wolf brings new soldiers: Granuloma, Kaposi, Leukemia, Sarcoid, Acne, Lichen, Tinea, Warts, Molluscum, SCC, BCC, Cysts.”