Correlation between bone imaging and the clinical picture in two unsuspected cases of progressive diaphyseal dysplasia (Engelmann's disease)

Camurati-Engelmann disease: unique variant featuring a novel mutation in TGFβ1 encoding transforming growth factor beta 1 and a missense change in TNFSF11 encoding RANK ligand

We report a 32-year-old man and his 59-year-old mother with a unique and extensive variant of Camurati-Engelmann disease (CED) featuring histopathological changes of osteomalacia and alterations within TGFβ1 and TNFSF11 encoding TGFβ1 and RANKL, respectively. He suffered leg pain and weakness since childhood and reportedly grew until his late 20s, reaching 7 feet in height. He had deafness, perforated nasal septum, torus palatinus, disproportionately long limbs with knock-knees, low muscle mass, and pseudoclubbing. Radiographs revealed generalized skeletal abnormalities, including wide bones and cortical and trabecular bone thickening in keeping with CED, except that long bone ends were also affected. Lumbar spine and hip BMD Z-scores were + 7.7 and + 4.4, respectively. Biochemical markers of bone turnover were elevated. Hypocalciuria accompanied low serum 25-hydroxyvitamin D (25[OH]D) levels. Pituitary hypogonadism and low serum insulin-like growth factor (IGF)-1 were present. Karyotype was normal. Despite vitamin D repletion, iliac crest histology revealed severe osteomalacia. Exon 1 of TNFRSF11A (RANK), exons 2, 3, and 4 of LRP5, and all coding exons and adjacent mRNA splice junctions of TNFRSF11B (OPG), SQSTM1 (sequestosome 1), and TNSALP (tissue nonspecific alkaline phosphatase) were intact. His asymptomatic and less dysmorphic 5'11″ mother, also with low serum 25(OH)D, had milder clinical, radiological, biochemical, and histopathological findings. Both individuals were heterozygous for a novel 12-bp duplication (c.27_38dup, p.L10_L13dup) in exon 1 of TGFβ1, predicting four additional leucine residues in the latency-associated-peptide segment of TGFβ1, consistent with CED. The son was also homozygous for a single base transversion in TNFSF11, predicting a nonconservative amino acid change (c.107C > G, p.Pro36Arg) in the intracellular domain of RANKL that was heterozygous in his nonconsanguineous parents. This TNFSF11 variant was not found in the SNP Database, nor in published TNFSF11 association studies, but it occurred in four of the 134 TNFSF11 alleles (3.0%) we tested randomly among individuals without CED. Perhaps the unique phenotype of this CED family is conditioned by altered RANKL activity.

Marked phenotypic variability in progressive diaphyseal dysplasia (Camurati-Engelmann disease): report of a four-generation pedigree, identification of a mutation in TGFB1, and review

Progressive diaphyseal dysplasia (PDD) (Camurati-Engelmann disease) is an autosomal dominant craniotubular dysplasia characterized by hyperostosis and sclerosis of the diaphyses of the long bones and the skull. Mutations in transforming growth factor beta-1 (TGFB1) were recently found in patients with PDD. We report on a four-generation pedigree with seven individuals affected by PDD, linkage and mutational analysis results, and review the literature. This pedigree demonstrates the autosomal dominant inheritance pattern, remarkable variation in expressivity, and reduced penetrance. The most severely affected individual had progression of mild skull hyperostosis to severe skull thickening and cranial nerve compression over 30 years. His carrier father remained asymptomatic into his ninth decade and had no radiographic hyperostosis or sclerosis of the bones. Symptomatic relatives presented with lower limb pain and weakness. They were initially diagnosed with a variety of other conditions. Two of the symptomatic individuals were treated successfully with prednisone. We genotyped 7 markers from chromosome region 19q13.1-13.3 in 15 relatives and confirmed linkage to this region in this family. We screened the TGFB1 gene for mutations and identified a missense mutation resulting in an R218H substitution in the affected individuals, the asymptomatic obligate carrier, and another unaffected relative. We genotyped the family for seven known TGFB1 polymorphisms and a novel TAAA tetranucleotide repeat in intron 1. These polymorphisms did not appear to account for the variability in disease severity in this family. Our review illustrates how the disorder can significantly compromise health. Cranial involvement, which occurs in 61% of patients, can be severe, entrapping cranial nerves or causing increased intracranial pressure. Therapy with corticosteroids should be attempted in all symptomatic patients.