🦴 Achondrogenesis Type 1B & Atelosteogenesis Type II

Nelson Textbook of Pediatrics 22nd Edition | Lethal skeletal dysplasias caused by SLC26A2 (DTDST) mutations (sulfate transporter defect → impaired proteoglycan sulfation). Achondrogenesis type 1B: severe micromelia, very short ribs (narrow thorax), poor ossification of spine/skull, hydropic. Atelosteogenesis type II: club-shaped femurs/humeri (hypoplastic, flared ends), hypoplastic vertebrae, cleft palate. Both are autosomal recessive and uniformly lethal in the neonatal period (perinatal or early neonatal death).

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📋 30 Clinical Scenarios — Achondrogenesis 1B & Atelosteogenesis Type II

📇 High‑Yield Review Cards

🩺 Clinical Recognition: Lethal SLC26A2 Disorders

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📋 Stepwise Management of Lethal SLC26A2 Disorders

🔑 Key Principles — Nelson Chapter 738
• Gene: SLC26A2 (DTDST) — encodes sulfate transporter. Autosomal recessive. Impaired proteoglycan sulfation → abnormal cartilage matrix.
• Achondrogenesis type 1B: Most severe. Severe micromelia, very short ribs (narrow thorax → pulmonary hypoplasia), poor ossification of vertebral bodies and skull. Hydropic, stillborn or die shortly after birth. Prenatal ultrasound diagnosis.
• Atelosteogenesis type II (AO-II): Club-shaped femurs and humeri (hypoplastic, flared metaphyses), hypoplastic vertebrae, cleft palate, short ribs. Neonatal lethal (respiratory insufficiency).
• Management: Perinatal palliative care, genetic counseling (25% recurrence risk), prenatal diagnosis for future pregnancies.

    ⚡ Reflex Prompts — Clinical Decisions

    📖 Summary: Achondrogenesis 1B & Atelosteogenesis Type II (Nelson 738)