Introduction: Vitamin D-dependent rickets type 2 (VDDR2) is traditionally defined by biallelic vitamin D receptor (VDR) mutations causing resistance to 1,25(OH)₂D. We describe a case of the classical VDDR2 phenotype with a single VDR mutation and an interesting physiological adaptation. Case: A female diagnosed with rickets at age three presented with a femoral fracture, severe short stature, hypocalcemia (2.1 mmol/L; NR 2.35–2.70), hypophosphatemia (0.8 mmol/L; NR 1.5–2.10), and evidence of renal phosphate wasting (TMP/GFR 0.5 mmol/L; NR 1.5–2.4). Biochemistry showed markedly elevated alkaline phosphatase (1,227 IU/L; NR 50–136) and secondary hyperparathyroidism (20.7 pmol/L; NR 0.8–7.8). Despite hypocalcemia, 1,25(OH)₂D was significantly elevated (>450 pmol/L; NR 60–150), consistent with VDDR2. There was no initial family history; however, subsequent evaluation of her mother—prompted by the patient’s diagnosis—revealed a similar biochemical profile, along with short stature (142 cm) and a history of multiple fractures. Genetic analysis in both individuals identified a heterozygous missense mutation in exon 10 of the VDR gene, affecting the ligand-binding domain, supporting a pattern of dominant inheritance. The patient was treated with cholecalciferol (1,200 IU daily), calcitriol (5–6 µg daily), and calcium carbonate (2,000 mg daily). Although biochemical responsiveness to therapy was evident, poor adherence resulted in suboptimal metabolic control throughout childhood and adolescence, including a second fracture at age 15 and a final adult height of 124 cm. Notably, calcium and phosphate levels progressively normalized after puberty, with sustained biochemical stability despite the patient omitting the treatment. Conclusion This case provides two important insights. First, it represents the fourth reported case worldwide demonstrating a dominant-negative effect of a VDR gene mutation, whereby a single mutant receptor interferes with wildtype VDR function. Second, it highlights postpubertal calcium adaptation, in which vitamin D–independent intestinal absorption may restore mineral homeostasis, and disease severity can attenuate over time through adaptive physiological mechanisms.
Calcium ; Mutation ; Vitamin D ; Rickets

Introduction: X-linked hypophosphatemia (XLH) is a rare genetic disorder caused by PHEX mutations, characterized by chronic hypophosphatemia and renal phosphate wasting, resulting in skeletal, dental, and extra-skeletal complications. To date, no data from Malaysia are currently available on clinical characteristics or health-related quality of life (HRQoL) in paediatric patients. Methodology: This cross-sectional study evaluated HRQoL among children and adolescents with XLH, using validated PROMIS (PatientReported Outcomes Measurement Information System) instruments, sociodemographic and clinical factors associated with HRQoL. This includes children and adolescents with confirmed XLH followed up at Universiti Malaya Medical Centre (UMMC) between November 2024 and March 2025. Results: Seventeen patients were analyzed (76.5% female and 23.5% male). The mean age at symptom onset was 2.82 ± 2.42 years, with a mean age at diagnosis of 5.21 ± 3.29 years. All patients continued to have musculoskeletal complications, including short stature (76.5%), bowing of legs (76.5%), bone/joint pain (47.1%), muscle pain (47.1%), and dental complications (52.9%). Serum alkaline phosphatase improved significantly (p = 0.011); persistent hypophosphatemia and ongoing musculoskeletal manifestations indicated suboptimal disease control. Elevated parathyroid hormone levels and an increase in urine calciumto-creatinine ratio (p = 0.020) lead to secondary hyperparathyroidism and nephrocalcinosis. Adherence to conventional therapy was poor. Non-adherence was associated with worse pain outcomes (higher pain interference [p = 0.037] and greater pain intensity [p = 0.025]). PROMIS scores revealed severely impaired mobility (mean T-score 31.31 ± 12.17), increased fatigue (mean T-score 54.22 ± 7.60), and high pain interference (mean T-score 63.11 ± 9.50). Larger household size was also strongly associated with higher pain intensity (p = 0.004). Conclusion Malaysian children and adolescents with XLH continue to have significantly poor HRQoL, particularly in mobility, fatigue, and pain. These findings highlight the need for access to targeted therapies, such as burosumab, to improve long-term outcomes and QOL in XLH patients.
Adolescent ; Child ; Familial Hypophosphatemic Rickets ; Malaysia ; Quality of Life

Introduction: We report an insidious presentation of hypocalcemic dilated cardiomyopathy (HDCM) in an infant with nutritional rickets and severe hypocalcemia, highlighting the myocardium’s strict reliance on calcium-phosphate homeostasis. Case: A 3-month-old, small-for-gestational-age male (birth weight: 1.93 kg), with congenital cataracts and persistent neonatal cholestasis (negative hepatopathy and congenital infection screens) presented acutely with post-feeding cyanosis, requiring intubation for aspiration pneumonia. The mother denied prior apneic episodes, seizures, feeding difficulties, or heart failure symptoms. Clinically, there was no murmur or hyperactive pericardium. Chest radiograph revealed globular cardiomegaly. Echocardiography confirmed HDCM (LVEF 41%). Bloodwork revealed profound hypocalcemia (1.16 mmol/L; normal 2.1–2.6), hyperphosphatemia (2.97 mmol/L), and markedly elevated alkaline phosphatase (2,411 IU/L). 25(OH)D3 was deficient (34.08 nmol/L). Secondary hyperparathyroidism (iPTH 19.55 pmol/L) represented an appropriate response. The mother had introduced goat’s milk instead of cow’s milk due to inadequate lactation. She took no supplements during pregnancy and was also vitamin D deficient. Management included IV calcium gluconate, targeted antifailure therapy (captopril, furosemide, spironolactone), and mechanical ventilation. High-dose cholecalciferol replenished depleted stores, alongside an active vitamin D analog (alfacalcidol) to bypass impaired hepato-intestinal pathways, stimulating calcium absorption. Extubated after 2 weeks with stabilized serum calcium, he was discharged on anti-failure therapy, oral calcium carbonate (54 mg/kg/day elemental), D-cure 25,000 IU 4-weekly, Ursodeoxycholic acid (45 mg 12-hourly), and multivitamins. Repeat echocardiography is planned at 3 months. Conclusion This case underscores the vulnerability to nutritional rickets and late-onset hypocalcemia in SGA infants with inadequate maternal nutrition and impaired GI absorption. The calcium-phosphate axis is easily disrupted; highphosphate substitutes (goat’s milk) precipitously unmask hypocalcemia, overwhelming compensatory hyperparathyroidism. Proactive, dual-therapy metabolic supplementation is paramount to avert catastrophic, yet reversible, HDCM.
Cardiomyopathies ; Rickets

Abstract Vitamin D deficiency is a significant health issue, particularly among office workers. This literature review emphasizes the availability of evidence on vitamin D deficiency and its impacts on musculoskeletal health and immune functions, especially amongst office workers. A literature search of PubMed, Scopus, and Web of Science identified relevant studies on the relationship between vitamin D status and musculoskeletal health and infection risks, highlighting the prevalence of vitamin D deficiency in office workers due to limited sunlight exposure and sedentary lifestyles. The risks of osteoporosis, muscle weakness, and musculoskeletal pain, as well as impaired immune system function, are carefully examined. Potential intervention strategies include implementing work schedules allowing for outdoor breaks, providing access to vitamin D-fortified foods or supplements, and routine screening for vitamin D levels. Addressing the low level of vitamin D in office workers is essential for promoting musculoskeletal health, supporting immune functions, and enhancing workforce productivity. This review underscores the need for further research and the implementation of evidence-based interventions to mitigate the impact of vitamin D deficiency in this population.
Vitamin D deficiency ; office workers ; musculoskeletal ; Immunity

OBJECTIVE: To explore the corrective strategies and effectiveness of osteotomy surgery for severe lower limb deformities in hypophosphatemic rickets. METHODS: A retrospective analysis was conducted on 29 patients with severe lower limb deformities of hypophosphatemic rickets who underwent surgical treatment between February 2012 and August 2024. There were 9 males and 20 females. The age ranged from 13 to 53 years, with an average of 24.6 years. All patients were deformities of both lower limbs, presenting as 24 cases of O-shaped legs, 2 cases of wind-blown deformities, and 3 cases of X-shaped legs. Based on the full-length films of both lower limbs in the standing position before operation, the osteotomy planes of the femur, tibia, and fibula were designed. Among them, if both the same-sided thigh and leg were deformed, staged surgeries of both lower limbs were selected. If only the thigh or leg were deformed, simultaneous surgeries of both lower limbs were selected. The femur deformity was corrected immediately after osteotomy at the deformed plane; the osteotomy fragment was temporarily controlled with an external fixator, which was removed after perform internal fixation with a steel plate. After fibular osteotomy, the Ilizarov frame or Taylor frame was installed on the tibia and fibula. The threaded rods were removed and then tibial osteotomy was performed on the deformed plane. Patients using the Taylor frame did not undergo deformity correction during operation. The external fixators were adjusted starting 7 days after operation to correct the varus, valgus, and rotational deformities of the lower limb. Patients using the Ilizarov frame corrected the rotational deformity of the tibia during operation. The external fixator was adjusted starting 7 days after operation to correct the varus and valgus deformities of the lower limb. During the treatment period, the patient could walk with partial weight-bearing on the operated limb with crutches. The external fixator was removed after the bone healed. Before operation and at last follow-up, the medial proximal tibial angle (MPTA), lateral distal tibial angle (LDTA), posterior proximal tibial angle (PPTA), anterior distal tibial angle (ADTA), anatomic lateral distal femoral angle (aLDFA), posterior distal femoral angle (PDFA), and mechanical axis deviation (MAD), lower limb rotation, limb length discrepancy (LLD) were measured. The self-made scoring criteria were adopted to evaluate the degree of lower limb deformity of the patients. RESULTS: All operations were successfully completed, and no complications such as nerve or vascular injury occurred. The adjustment time of the external fixator of the lower limb after operation was 28-46 days, with an average of 37.4 days. The wearing time of the external fixator ranged from 134 to 398 days, with an average of 181.5 days. Mild pin tract infections occurred in 2 limbs. The osteofascial compartment syndrome occurred in 1 limb after operation. No complications related to orthopedic adjustment of the external fixator occurred in other patients. All patients were followed up 6-56 months, with an average of 28.2 months. At last follow-up, full-length films of both lower limbs in the standing position showed that the coronal mechanical axes of the lower limbs of all patients returned to the normal. At last follow-up, MPTA, LDTA, PPTA, aLDFA, PDFA, MAD, lower limb rotation, LLD, and the score of lower limb deformity significantly improved when compared with those before operation ( P<0.05). There was no significant difference in ADTA between pre- and post-operation ( P>0.05). The degree of lower limb deformity were rated as moderate in 2 cases and poor in 27 cases before operation and as excellent in 7 cases, good in 18 cases, and moderate in 4 cases at last follow-up, with an excellent and good rate of 86.2%. CONCLUSION For severe lower limb deformities in hypophosphatemic rickets, immediate correction of deformities with femoral osteotomy and internal plate fixation, as well as gradually correction of deformities with tibiofibular osteotomy and circular external fixation (Ilizarov frame or Taylor frame), have satisfactory therapeutic effects.
Humans ; Male ; Osteotomy/instrumentation* ; Female ; Adult ; Retrospective Studies ; Tibia/abnormalities* ; Adolescent ; Femur/abnormalities* ; Middle Aged ; Fibula/surgery* ; Rickets, Hypophosphatemic/complications* ; Young Adult ; Treatment Outcome ; External Fixators ; Bone Plates ; Lower Extremity Deformities, Congenital/etiology*

Multiple myeloma (MM) is a common hematologic malignancy that originates from precursor conditions such as monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). Identifying its risk factors is crucial for early intervention. The etiology of MM is multifactorial, involving race, familial clustering, gender, age, obesity, cytogenetic abnormalities, and environmental exposures. Among these, cytogenetic abnormalities and modifiable factors play pivotal roles in MM pathogenesis and progression. 1) cytogenetic abnormalities. Primary abnormalities [e.g., hyperdiploidy, t(11;14), t(14;16)] emerge at the MGUS stage, while secondary abnormalities [e.g., 1q+, del(17p)] drive disease progression. The accumulation of 1q+ promotes clonal evolution, and del(17p) is associated with significantly reduced survival. 2) modifiable risk factors. Obesity promotes MM via the acetyl-CoA synthetase 2 (ACSS2)-interferon regulatory factor 4 (IRF4) pathway. Vitamin D deficiency weakens immune surveillance. Exposure to herbicides such as Agent Orange and glyphosate increases MGUS incidence. Insufficient UV exposure, by reducing vitamin D synthesis, elevates MM risk. Gut microbiota dysbiosis (enrichment of nitrogen-cycle bacteria and depletion of short-chain fatty acids producers) induces chromosomal instability through the ammonium ion-solute carrier family 12 member 22 (SLC12A2)-NEK2 axis. Therefore, risk-based screening among high-risk populations (e.g., those who are obese, elderly, or chemically exposed), along with early interventions targeting cytogenetic abnormalities [e.g., B cell lymphoma 2 (Bcl-2) inhibitors for t(11;14), ferroptosis inducers for t(4;14)] and modifiable factors (e.g., vitamin D supplementation, gut microbiota modulation), may effectively delay disease progression and improve prognosis.
Humans ; Multiple Myeloma/epidemiology* ; Risk Factors ; Obesity/complications* ; Chromosome Aberrations ; Monoclonal Gammopathy of Undetermined Significance/etiology* ; Gastrointestinal Microbiome ; Vitamin D Deficiency/complications* ; Precancerous Conditions/genetics*

Objective:To observe and analyze the levels of vitamin D（VD） and their influencing factors in children undergoing adenoidectomy and/or tonsillectomy. Methods:A total of 147 children who received adenoidectomy and/or tonsillectomy in our hospital from November 2018 to March 2019 were selected as the experimental groups, gender and age matched 147 healthy children of the same period were selected as the control group. The differences of VD levels between the two groups were compared, the factors affecting VD levels were investigated, and patients with VD deficiency/insufficiency in the experimental groups were followed up postoperatively. Results:The VD levels of the experimental groups were（19.6±6.6） ng/mL and those of the control groups were （22.5±6.5）ng/mL, which was significantly different （P<0.01）. The experimental groups were divided into inflammation groups and Sleeping disorder breathing（SDB）groups. The VD levels of the two groups were （19.1±6.7）ng/mL and （21.9±6.4）ng/mL, which was significantly different （P<0.05）. Regression analysis showed that VD levels were negatively correlated with age, body mass index （BMI）, adenoid hypertrophy, tonsil hypertrophy and Anti-streptolysin O（ASO）levels （P<0.05）. VD values were remeasured one year postoperatively in 23 of 72 children in the VD deficiency/deficiency groups, and there was a statistically significant difference between preoperative and postoperative VD values[（14.3±3.9）ng/mL and （17.1±5.5） ng/mL, respectively, P<0.05]. There was a significant difference in postoperative VD value between the inflammation groups and the SDB groups[ （15.6±5.9） ng/mL and （20.5±2.1） ng/mL, respectively, P<0.05]. Conclusion:Children who underwent adenoidectomy and/or tonsillectomy had lower VD levels than healthy children.VD levels decreased with increasing age,BMI and ASO values,and associated with the size of adenoid and tonsil. Preoperative VD levels were lower in the inflammation groups, adenoidectomy and/or tonsillectomy improved VD deficiency/insufficiency status, and postoperative elevation of VD levels was more pronounced in the SDB groups.
Humans ; Tonsillectomy ; Adenoidectomy ; Vitamin D/blood* ; Vitamin D Deficiency ; Male ; Female ; Postoperative Period ; Child ; Case-Control Studies ; Child, Preschool

Humans ; Mesenchymoma/surgery* ; Soft Tissue Neoplasms ; Osteomalacia

OBJECTIVES: To study the correlation between 25-hydroxyvitamin D [25-(OH)D] and nephroblastoma in children and its value in assessing the prognosis of the disease. METHODS: A total of 50 children with nephroblastoma who were admitted from January 2018 to December 2022 were included as the nephroblastoma group, and according to the postoperative pathological type, they were divided into a good prognosis group with 38 children and a poor prognosis group with 12 children. A total of 50 healthy children who underwent physical examination during the same period of time served as the healthy control group. The above groups were compared in terms of serum creatinine and 25-(OH)D level. A Spearman correlation analysis was used to investigate the correlation between serum 25-(OH)D level and therapeutic effect reaction. A multivariate logistic regression analysis was used to identify the risk factors affecting the prognosis of nephroblastoma in children. RESULTS: The nephroblastoma group had significantly lower levels of serum creatinine and 25-(OH)D than the healthy control group (P<0.05). Compared with the good prognosis group, the poor prognosis group had a significantly larger tumor diameter, a significantly higher proportion of children with stage III-IV tumors, a significantly higher rate of tumor metastasis, and significantly lower serum levels of creatinine and 25-(OH)D (P<0.05). The Spearman correlation analysis showed that serum 25-(OH)D level was negatively correlated with therapeutic effect reaction (r_s=-0.685, P<0.001). The multivariate logistic regression analysis showed that tumor diameter ≥10 cm, stage III-IV tumors, presence of tumor metastasis, and 25-(OH)D <19 ng/mL were closely associated with the poor prognosis of nephroblastoma in children (P<0.05). Serum 25-(OH)D level had an area under the curve of 0.805 (95%CI: 0.706-0.903, P<0.001) in evaluating the prognosis of nephroblastoma in children, with a Youden index of 0.512, a sensitivity of 0.938, and a specificity of 0.575 at the optimal cut-off value of 1.764 ng/mL. CONCLUSIONS There is a significant correlation between 25-(OH)D level and the prognosis of nephroblastoma in children, and 25-(OH)D can be used for prognosis prediction.
Humans ; Child ; Creatinine ; Vitamin D Deficiency/complications* ; Vitamin D ; Calcifediol ; Prognosis ; Wilms Tumor ; Kidney Neoplasms/complications*

OBJECTIVES: To study the value of serum fibroblast growth factor 23 (FGF23) in the diagnosis of hypophosphatemic rickets in children. METHODS: A total of 28 children who were diagnosed with hypophosphatemic rickets in Children's Hospital of Nanjing Medical University from January 2016 to June 2021 were included as the rickets group. Forty healthy children, matched for sex and age, who attended the Department of Child Healthcare of the hospital were included as the healthy control group. The serum level of FGF23 was compared between the two groups, and the correlations of the serum FGF23 level with clinical characteristics and laboratory test results were analyzed. The value of serum FGF23 in the diagnosis of hypophosphatemic rickets was assessed. RESULTS: The rickets group had a significantly higher serum level of FGF23 than the healthy control group (P<0.05). In the rickets group, the serum FGF23 level was positively correlated with the serum alkaline phosphatase level (r_s=0.38, P<0.05) and was negatively correlated with maximum renal tubular phosphorus uptake/glomerular filtration rate (r_s=-0.64, P<0.05), while it was not correlated with age, height Z-score, sex, and parathyroid hormone (P>0.05). Serum FGF23 had a sensitivity of 0.821, a specificity of 0.925, an optimal cut-off value of 55.77 pg/mL, and an area under the curve of 0.874 in the diagnosis of hypophosphatemic rickets (P<0.05). CONCLUSIONS Serum FGF23 is of valuable in the diagnosis of hypophosphatemic rickets in children, which providing a theoretical basis for early diagnosis of this disease in clinical practice.
Child ; Humans ; Fibroblast Growth Factor-23 ; Fibroblast Growth Factors ; Familial Hypophosphatemic Rickets/diagnosis* ; Rickets, Hypophosphatemic/diagnosis*