Which statement is true about Pseudohypoparathyroidism Type 1A?

Which statement is true about Pseudohypoparathyroidism Type 1A?

• A. It lacks AHO phenotype and lacks PTH resistance
• B. It has AHO phenotype and PTH resistance
• C. It has AHO phenotype but no PTH resistance
• D. It lacks AHO phenotype but has PTH resistance

Answer: (B)

Pseudohypoparathyroidism type 1A combines physical features of Albright hereditary osteodystrophy with resistance to parathyroid hormone due to a GNAS mutation that’s expressed in a parent-of-origin–dependent way. The AHO phenotype includes brachydactyly, round facies, short stature, subcutaneous ossifications, and other skeletal/soft-tissue features. The PTH resistance is end-organ, meaning the kidneys (and sometimes bone) don’t respond properly to PTH, so despite elevated or inappropriately normal PTH, calcium remains low and phosphate stays high. This pattern—both the AHO-like appearance and clear PTH resistance—best matches the true statement. If there were no AHO features, or if there were PTH resistance without AHO, that would correspond to other related disorders, not PHP type 1A.

Pseudohypoparathyroidism type 1A combines physical features of Albright hereditary osteodystrophy with resistance to parathyroid hormone due to a GNAS mutation that’s expressed in a parent-of-origin–dependent way. The AHO phenotype includes brachydactyly, round facies, short stature, subcutaneous ossifications, and other skeletal/soft-tissue features. The PTH resistance is end-organ, meaning the kidneys (and sometimes bone) don’t respond properly to PTH, so despite elevated or inappropriately normal PTH, calcium remains low and phosphate stays high. This pattern—both the AHO-like appearance and clear PTH resistance—best matches the true statement. If there were no AHO features, or if there were PTH resistance without AHO, that would correspond to other related disorders, not PHP type 1A.