Transforming growth factor-β1 gene mutations and phenotypes in pediatric patients with Camurati‑Engelmann disease

Clinical characteristics and identification of a novel TGFB1 variant in three unrelated Chinese families with Camurati-Engelmann disease

Background

To investigate the clinical characteristics and molecular diagnosis of Camurati‐Engelmann disease (CAEND) in Chinese individuals.

Methods

We recruited six patients aged 14 to 45 years in three unrelated families with CAEND, including five females and one male. Clinical manifestations, biochemical tests, and radiographic examinations were analyzed. The TGFB1 gene variants were further identified by Sanger sequencing. In addition, one female patient was followed up for 5 years.

Results

The onset age of the patients ranged from 1 to 6 years. All of them had family histories and consisted of an autosomal dominant inheritance pattern. Gait disturbance, fatigue, progressive bone pain, muscle atrophy, and weakness were the main complaints. Laboratory examinations revealed that the inflammatory markers were at high levels, in addition to the increased bone metabolism indicators. The thickened diaphysis of long bones and the narrowed medullary cavity was observed by radiography. Furthermore, bone scintigraphy detected abnormal symmetrical radioactive concentrations in the affected regions of bone. Sanger sequencing identified a missense heterozygous variant in exon 4 of the TGFB1 gene in families 1 and 2, resulting in Arg218Cys, which confirmed CAEND. Moreover, one novel variant c.669C > G in exon 4 of the TGFB1 gene harboring Cys223Trp was detected in family 3. Subsequent bioinformatics software predicted that the novel variant was pathogenic. Of interest, III:2 in family 3 experienced heart valve defects and tachycardia at birth, which had never been reported in CAEND patients before. Moreover, the response to drug treatment is also full of contradictions and is worthy of further study.

Conclusion

Besides the typical CAEND manifestations, the new phenotypic characteristics of tachycardia and heart valve defects were first reported in one woman carrying the novel variant p.Cys223Trp in TGFB1 the gene. In addition, we demonstrated that increased bone metabolism indicators and inflammatory markers may possess auxiliary diagnosis for CAEND.

Alendronate disturbs femoral growth due to changes during immunolocalization of transforming growth factor-β1 and bone morphogenetic protein-2 in epiphyseal plate

BACKGROUND

The epiphyseal growth plate is an important anatomical segment localized on the ends of a long bone. Despite the abovementioned atractive reasons for alendronate’s use, few data on the effect of alendronate during epiphyseal growth exist.

AIM

Verify the effect of alendronate on the growth epiphyseal plate, and compare its effect with the size of the femur during the double-staining of the immunolocalization of transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-2 (BMP2) in endochondral ossifing in specimens that have received alendronate.

METHODS

Forty newborn rats were randomly divided into two groups: a control group (were given applications of 1 mg/kg physiologic saline) and a group that received Alendronate (a dose of 2.5 mg/kg). These groups were then divided into two subgroups for euthanasia in two and 12 d of life. After euthanasia, the femurs were removed, and the femoral bones were measured linearly between the apex of the greater trochanter until the lower intercondylar midlle face to verify the probable bone growth between 3 and 12 d in control and alednroanto treated rats. Posteriorly, the surgical pieces were also sent to the histopathology laboratory to produce histological slides. The obtained slides were stained with hematoxylin and eosin to measure each of the cartilage zones in endochondral development. and other slides were immunohistochemically tested for anti- TGF-β1 and BMP-2 antibodies to investigate the immunolocalization of these proteins in the epiphyseal plaque area.

RESULTS

On the third day, some diferences between the control group and specimens treated with alendronate were verified. Macroscopiccaly, we found similarities in size between the femoral bones when we compared the control group with the specimens that received alendronate. On the 12^th day, the bone size of the mice receiving the drug was significantly smaller than those of the control group. These results coincide with changes in the TGF-β1 and BMP-2 expression. In the specimens that received alendronate, the TGF-β1 was expressed in some sites of trabecular bone that was neoformed, peripherally to the bone marrow area. The BMP-2 was also positive in proliferative chondrocytes and hypertrofic chondrocytes. On the 12^th day, all layers of chondrocytes exhibited positivity for BMP-2 in the specimens that received alendronate. In the interface between the trabecular bone and cartilage, an area of disorganized bone deposition was evident. Neoformed bone also appeared to be different at 12 d. In the control group, BMP-2 was positive in an intense area of bone trabeculae, whereas the alendronate-treated group showed TGF-β1 positive trabeculae and a greater bone area.

CONCLUSION

Alendronate alters the immunolocalization of TGF-β1 and BMP-2 simultaneously, a condition that changes the usual histological aspects of the cartilage zone and impairs epiphysis growth and femur growth.

Significant Improvement of Clinical Symptoms, Bone Lesions, and Bone Turnover after Long-Term Zoledronic Acid Treatment in Patients with a Severe Form of Camurati-Engelmann Disease

Camurati-Engelmann disease (CED) is an ultrarare autosomal dominant bone dysplasia. Cortical thickening of the diaphyses of the long bones with narrowing of the medullary cavity are associated with bone pain, waddling gait, muscular weakness, easy fatigability, and a marfanoid body habitus. There is no specific treatment for CED. Nonsteroidal anti-inflammatory drugs or glucocorticoids are ineffective in improving bone lesions. A family with a mild to severe form of CED is described. Two patients received long-term bisphosphonate treatment: the 19-year-old female proband was treated with zoledronic acid for 2.2 years; the 4-year-old male proband was treated with neridronic acid for 16 months and with zoledronic acid for an additional 18 months. In both probands, zoledronic acid treatment significantly improved the clinical symptoms, bone lesions, ambulation, and body habitus. Before treatment, both probands showed a marked increase in serum levels of osteocalcin, procollagen type I N-terminal propeptide, and cross-linked carboxyterminal telopeptide of type I collagen, reflecting an increased bone turnover. Bone marker levels returned to their normal values during treatment. Zoledronic acid treatment may be an important therapeutic option in patients with severe CED. Biochemical markers of bone turnover could be considered as surrogate indexes of CED activity.

Clinical diagnosis and mutation analysis of a Chinese family with Camurati-Engelmann disease

Camurati-Engelmann disease (CED) is a rare autosomal dominant bone disorder caused by a mutation in transforming growth factor β1 (TGFβ1). The present study aimed to identify a Chinese family with suspected CED based on the clinical symptoms, including pain in extremities, waddling gait, muscle weakness, cortical thickening of the diaphysis of the long bones, and sclerosis of the skull, facial bone, and pelvis. Molecular analysis revealed the presence of the p.Glu169Lys (E169K) mutation in exon 2 of TGFβ1 in patients when compared with the controls. Therefore, the Chinese family was diagnosed with CED due to the presence of the E169K mutation. The present study emphasized the importance of clinical and genetic evidence for the diagnosis of CED. The data presented in the present study are of significance to clinicians, as well as genetic counselors, in the prenatal screening of CED.

Mild Camurati‑Engelamann disease presenting with exophthalmos as the first and only manifestation: A case report

Camurati-Engelmann disease (CED; MIM 131300), or progressive diaphyseal dysplasia, is a rare autosomal dominant bone disease, which is caused by mutations in the transforming growth factor‑β1 (TGFβ1) gene on chromosome 19q13.1‑13.3. Extremely variable penetrance has been reported to be associated with CED, the most common features of which are limb pain, waddling gait and muscle weakness. The present study reported on a consanguineous Chinese family with one affected individual that initially presented with exophthalmos, which has not previously been reported as an initial manifestation of CED. The proband was a 22-year-old woman that presented with progressive proptosis. Except for increased serum levels of alkaline phosphatase and C‑terminal telopeptide of type I collagen, no other biochemical abnormalities were detected. Whole‑body radiological and bone scintigraphic investigations revealed that hyperostosis and sclerosis predominantly affected the cranial bones, including the skull base, and only mildly affected the long bones. A heterozygous mutation involving a G to A transition at the cDNA position +653 of TGFβ1 was detected in the patient only, but not in her family members, by automated DNA sequencing using an ABI DNA sequencer (Model 377). Based on the clinical, biochemical, radiological and genetic findings, a diagnosis of CED was confirmed. Considering the phenotypic variability associated with CED and the unique manifestations of the patient described in the present study, CED should be taken into account regarding the differential diagnosis of exophthalmos.