PAPSS2-Related Brachyolmia: Clinical and Radiographic Features and Growth Hormone Therapy of One Chinese Case.

Brachyolmia type 4 (BCYM4, OMIM 612847) is a rare skeletal dysplasia characterized by mild epiphyseal and metaphyseal abnormalities. We report a Chinese boy with brachyolmia caused by a novel compound heterozygous mutation in the gene. Prenatal ultrasound revealed shortened long bones, and his birth length was markedly reduced (45 cm, -3.11 SD). Clinical and radiographic findings were consistent with brachyolmia, and genetic analysis confirmed the diagnosis of BCYM4 at 2 years and 9 months old. During follow-up, the patient exhibited progressive growth retardation. Under pediatric orthopedics supervision, growth hormone (GH) therapy was initiated to ameliorate his short stature since 5 years and 6 months old. Over a 2-year and 3-month treatment period, GH therapy significantly improved his growth velocity, with his height increasing from -5.02 SD to -3.87 SD. Notably, severe growth restriction was evident as early as 25 weeks' gestation, and spinal radiographs demonstrated persistent skeletal abnormalities. This case expands the phenotypic spectrum of BCYM4 and provides evidence supporting the efficacy of GH therapy in improving growth outcomes in patients with skeletal dysplasia-associated short stature.