The radiologic diagnosis of skeletal dysplasias: past, present and future.

Skeletal dysplasias have been recognised since recorded history began. The advent of radiography at the beginning of the 20th century and the subsequent introduction of departments of radiology have had tremendous impact and allowed conditions to be identified by their specific radiographic phenotypes. This has been enhanced by the addition of cross-sectional modalities (ultrasound, computed tomography and magnetic resonance imaging), which have allowed for prenatal recognition and diagnosis of skeletal dysplasias, and by the recent explosion in identified genes. There are more than 400 recognised skeletal dysplasias, many of which (due to their rarity) the practising clinician (radiologist, paediatrician, geneticist) may never come across. This article provides a historical overview of aids to the radiologic diagnosis of skeletal dysplasias.

Radiographic features of the skeleton in disorders of post-squalene cholesterol biosynthesis.

Disorders of post-squalene cholesterol biosynthesis are inborn errors of metabolism characterised by multiple congenital abnormalities, including significant skeletal involvement. The most frequent and best-characterised example is the Smith-Lemli-Opitz syndrome. Nine other disorders are known, namely autosomal-recessive Antley-Bixler syndrome, Greenberg dysplasia, X-linked dominant chondrodysplasia punctata, X-linked recessive male emopamil-binding protein deficiency, CHILD syndrome, CK syndrome, sterol C4 methyloxidase-like deficiency, desmosterolosis and lathosterolosis. This study provides an overview of the radiologic features observed in these diseases. A common pattern of limb abnormalities is recognisable, including polydactyly, which is typically post-axial and rarely interdigital and can involve all four limbs, and syndactyly of the toes. Chondrodysplasia punctata is specifically associated with a subgroup of disorders of cholesterol biosynthesis (Greenberg dysplasia, CHILD syndrome, X-linked dominant chondrodysplasia punctata, male emopamil-binding protein deficiency). The possible occurrence of epiphyseal stippling in the Smith-Lemli-Opitz syndrome, initially reported, does not appear to be confirmed. Stippling is also associated with other congenital disorders such as chromosomal abnormalities, brachytelephalangic chondrodysplasia punctata (X-linked recessive chondrodysplasia punctata, disruptions of vitamin K metabolism, maternal autoimmune diseases), rhizomelic chondrodysplasia punctata (peroxisomal disorders) and lysosomal storage disorders. In the differential diagnosis of epiphyseal stippling, a moth-eaten appearance of bones, asymmetry, or presence of a common pattern of limb abnormalities indicate inborn errors of cholesterol biosynthesis. We highlight the specific differentiating radiologic features of disorders of post-squalene cholesterol biosynthesis.

Acroscyphodysplasia as a phenotypic variation of pseudohypoparathyroidism and acrodysostosis type 2.

Acroscyphodysplasia (OMIM250215) is a distinctive form of metaphyseal dysplasia characterized by the distal femoral and proximal tibial epiphyses embedded in cup-shaped, large metaphyses known as metaphyseal scypho ("scypho" = cup) deformity. It is also associated with severe growth retardation and brachydactyly. The underlying molecular mechanism of acroscyphodysplasia has not yet been elucidated, although scypho-deformity of the knee has been reported in three patients with acrodysostosis due to a mutation in the PDE4D gene. We report on the clinical, radiological, and molecular findings of five female patients with acroscyphodysplasia; two were diagnosed as pseudohypoparathyroidism (PHP) or Albright hereditary osteodystropy, and the other three as acrodysostosis. They all had radiological findings consistent with severe metaphyseal scypho-deformity and brachydactyly. Heterozygous mutations were identified in the PHP patients consisting of one novel (p.Q19X) and one recurrent (p.R231C) mutation of the GNAS gene, as well as, in the acrodysostosis patients consisting of two novel mutations (p.T224I and p.I333T) of the PDE4D gene. We conclude that metaphyseal acroscyphodysplasia is a phenotypic variation of PHP or acrodysostosis caused by either a GNAS or PDE4D mutation, respectively.

Pseudoachondroplasia and multiple epiphyseal dysplasia: a 7-year comprehensive analysis of the known disease genes identify novel and recurrent mutations and provides an accurate assessment of their relative contribution.

Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED) are relatively common skeletal dysplasias resulting in short-limbed dwarfism, joint pain, and stiffness. PSACH and the largest proportion of autosomal dominant MED (AD-MED) results from mutations in cartilage oligomeric matrix protein (COMP); however, AD-MED is genetically heterogenous and can also result from mutations in matrilin-3 (MATN3) and type IX collagen (COL9A1, COL9A2, and COL9A3). In contrast, autosomal recessive MED (rMED) appears to result exclusively from mutations in sulphate transporter solute carrier family 26 (SLC26A2). The diagnosis of PSACH and MED can be difficult for the nonexpert due to various complications and similarities with other related diseases and often mutation analysis is requested to either confirm or exclude the diagnosis. Since 2003, the European Skeletal Dysplasia Network (ESDN) has used an on-line review system to efficiently diagnose cases referred to the network prior to mutation analysis. In this study, we present the molecular findings in 130 patients referred to ESDN, which includes the identification of novel and recurrent mutations in over 100 patients. Furthermore, this study provides the first indication of the relative contribution of each gene and confirms that they account for the majority of PSACH and MED.

Type 1 collagenopathy presenting with a Russell-Silver phenotype.

Osteogenesis imperfecta (OI) is a heterogeneous group of inherited disorders of bone formation, resulting in low bone mass and an increased propensity to fracture. It exhibits a broad spectrum of clinical severity, ranging from multiple fractures in utero and perinatal death, to normal adult stature and low fracture incidence. Extra-skeletal features of OI include blue sclera, hearing loss, skin hyperlaxity, joint hyperextensibility, and dentinogenesis imperfecta. The proα1(I) and proα2(I) chains of collagen 1 are encoded by the COL1A1 and COL1A2 genes, respectively; quantitative or qualitative defects in type I collagen synthesis usually manifest as types of OI or some sub-types of EDS. The majority of patients (about 90%) with a clinical diagnosis of OI have a mutation in the COL1A1 or COL1A2 genes, which shows an autosomal dominant pattern of inheritance. Six other genes, CRTAP, LEPRE1, FKBP10, PP1B, SP7/Osterix (OSX), and SERPINH1, are associated with autosomal recessive forms of OI. However, other, rare phenotypes have also been described. There are many differential diagnoses of the short, syndromic child, including chromosomal, single gene, and multifactorial causes. However, one condition of particular relevance in the context of this report is the Russell-Silver syndrome (RSS). As originally described, the RSS is a very specific condition. However, it has subsequently become an umbrella term for a heterogeneous group of conditions presenting with short stature and triangular shape to the face. A significant proportion of these are now believed to be due to imprinting defects at 11p15. However, the cause in many cases remains unknown. We describe two cases with a phenotypic overlap between OI and RSS who both have COL1A1 mutations. Thus, a type 1 collagenopathy should be considered in the differential diagnosis of syndromic short stature.

Early prenatal presentation of the cartilage-hair hypoplasia / anauxetic dysplasia spectrum of disorders mimicking recurrent thanatophoric dysplasia.

Three sibling fetuses identified with limb shortening and thoracic narrowing at twelve weeks' gestation on first trimester ultrasound examination are presented. The parents were non-consanguineous, Caucasian, healthy, of normal stature and had a healthy normal daughter. The radiographic abnormalities were highly suggestive of thanatophoric dysplasia, but molecular analysis failed to identify a pathogenic variant in FGFR3. The three fetuses were found to have identical compound heterozygous mutations in RMRP in trans, one inherited from the mother and one from the father. This represents the early prenatal presentation and fetal findings of metaphyseal dysplasia type McKusick (Cartilage-hair hypoplasia; CHH)/anauxetic dysplasia spectrum of disorders.

Diagnostic yield of rare skeletal dysplasia conditions in the radiogenomics era.

BACKGROUND: Skeletal dysplasia (SD) conditions are rare genetic diseases of the skeleton, encompassing a heterogeneous group of over 400 disorders, and represent approximately 5% of all congenital anomalies. Developments in genetic and treatment technologies are leading to unparalleled therapeutic advances; thus, it is more important than ever to molecularly confirm SD conditions. Data on 'rates-of-molecular yields' in SD conditions, through exome sequencing approaches, is limited. Figures of 39% and 52.5% have been reported in the USA (n = 54) and South Korea (n = 185) respectively. METHODS: We discuss a single-centre (in the UK) experience of whole-exome sequencing (WES) in a cohort of 15 paediatric patients (aged 5 months to 12 years) with SD disorders previously molecularly unconfirmed. Our cohort included patients with known clinical diagnoses and undiagnosed skeletal syndromes. Extensive phenotyping and expert radiological review by a panel of international SD radiology experts, coupled with a complex bioinformatics pipeline, allowed for both gene-targeted and gene-agnostic approaches. RESULTS: Significant variants leading to a likely or confirmed diagnosis were identified in 53.3% (n = 8/15) of patients; 46.7% (n = 7/15) having a definite molecular diagnosis and 6.7% (n = 1/15) having a likely molecular diagnosis. We discuss this in the context of a rare disease in general and specifically SD presentations. Of patients with known diagnoses pre-WES (n = 10), molecular confirmation occurred in 7/10 cases, as opposed to 1/5 where a diagnosis was unknown pre-test. Thus, diagnostic return is greatest where the diagnosis is known pre-test. For WGS (whole genome sequencing, the next iteration of WES), careful case selection (ideally of known diagnoses pre-test) will yield highest returns. CONCLUSIONS: Our results highlight the cost-effective use of WES-targeted bioinformatic analysis as a diagnostic tool for SD, particularly patients with presumed SD, where detailed phenotyping is essential. Thorough co-ordinated clinical evaluation between clinical, radiological, and molecular teams is essential for improved yield and clinical care. WES (and WGS) yields will increase with time, allowing faster diagnoses, avoiding needless investigations, ensuring individualised patient care and patient reassurance. Further diagnoses will lead to increased information on natural history/mechanistic details, and likely increased therapies and clinical trials.

Symmetrical enchondromatosis is associated with duplication of 12p11.23 to 12p11.22 including PTHLH.

We describe a patient with striking generalized symmetrical enchondromatosis of the tubular bones and a de novo duplication of chromosome 12p11.23 to 12p11.22. The PTHLH gene within this region encodes a ligand for PTHR1: mutations in the gene encoding this receptor are associated with some cases of Ollier disease, several skeletal dysplasias including Blomstrand, Eiken, and Jansen and down-regulation of PTHLH expression in brachydactyly type E. Our findings suggest that abnormal PTHLH-PTHR1 signaling may underly this unusual form of enchondromatosis and indicate that unlike most cases of Ollier disease it is dominantly inherited.

A clinical review and introduction of the diagnostic algorithm for thalidomide embryopathy (DATE).

Thalidomide embryopathy results from the ingestion of thalidomide in the first trimester during pregnancy, causing multiple forms of congenital abnormalities of variable severity that involve all systems. The skeletal findings most frequently affect the limbs, particularly the upper limbs and hands. Increasingly, several genetic disorders with similar birth defects have been identified. New cases of malformations owing to possible exposure to thalidomide continue to present through both historical and current usage. However, inadequate proof of ingestion, marked phenotypic variation and the possibility of an alternative genetic condition, hinder the diagnosis of thalidomide embryopathy. We introduce a 'diagnostic algorithm for thalidomide embryopathy' (DATE) diagnostic software that can potentially provide a numerical score for the likelihood of birth defects in an individual as being caused by exposure to thalidomide and to provide a differential diagnosis based on the pattern of malformation.

Clinical and radiological findings in Schinzel-Giedion syndrome.

The absence of a definitive genetic test for the autosomal recessive condition Schinzel-Giedion syndrome is a significant handicap to the recognition of this disorder. Radiological features have been an important aspect of many of the published cases. In a series of six cases, we now establish a consistency among many of the radiological features in affected cases which will be an important diagnostic aid in identifying future cases. This is confirmed by reference to an extensive review of previously published instances of the syndrome. Moreover, the clinical data, including previously unpublished photographs, which we detail from our patients will assist in enhanced diagnosis in the future.

Chondrodysplasia punctata: a clinical diagnostic and radiological review.

Chondrodysplasia punctata (CDP) is associated with a number of disorders, including inborn errors of metabolism, involving peroxisomal and cholesterol pathways, embryopathy and chromosomal abnormalities. Several classification systems of the different types of CDP have been suggested earlier. More recently, the biochemical and molecular basis of a number of CDP syndromes has recently been elucidated and a new aetiological classification has emerged. Here we provide an updated version with an overview of the different types of CDP, a discussion of the aetiology and a description of the clinical and radiographic findings. An investigative guideline to help determine the exact diagnosis in new cases is also presented.

Treatment of postpartum depression in mothers: Secondary benefits to the infants.

This study examined the quality of mother-infant interaction and levels of perceived stress and parenting efficacy in association with mothers' levels of depression among mothers with significant depressive symptoms during the postpartum period, who were followed prospectively during treatment, and their infants less than 6 months old. Mothers with postpartum depression (n = 19) were treated with medication, and the mothers were observed with their infants prior to treatment and 3 and 6 months later. A comparison group of nondepressed mothers (n = 25) was included to control for the normal developmental changes associated with the postpartum period. The depressed women experienced a significant reduction in depressive symptoms and did not differ significantly from well mothers 6 months after beginning treatment. Despite initial levels of parenting quality and depression, mothers' reduced levels of depression, after 12 weeks of treatment, were associated with improvements in the quality of their interactions with their infants and with improvements in their infants' quality of play. For both perceived stress and parenting efficacy beliefs, both depressed and well mothers showed a significant improvement from the initial to the 12-week visit, and there were no significant differences between depressed and well mothers' perceived stress or efficacy beliefs at the 12-week visit. Depression at the 12-week visit did not predict perceived stress or efficacy beliefs beyond the variance accounted for by initial levels of those variables and depression. The impact of reducing levels of maternal depression symptoms supports theoretical models of the role of parenting in the association between maternal depression and child functioning. Further, these findings support the benefits to infants of reducing depression in mothers.

Preselection of cases through expert clinical and radiological review significantly increases mutation detection rate in multiple epiphyseal dysplasia.

Skeletal dysplasias are difficult to diagnose for the nonexpert. In a previous study of patients with multiple epiphyseal dysplasia (MED), we identified cartilage oligomeric matrix protein (COMP) mutations in only 36% of cases and suspected that the low-mutation detection rate was partially due to misdiagnosis. We therefore instituted a clinical-radiographic review system, whereby all cases were evaluated by a panel of skeletal dysplasia experts (European Skeletal Dysplasia Network). Only those patients in whom the diagnosis of MED was confirmed by the panel were screened for mutations. Under this regimen the mutation detection rate increased to 81%. When clinical-radiological diagnostic criteria were relaxed the mutation rate dropped to 67%. We conclude that expert clinical-radiological review can significantly enhance mutation detection rates and should be part of any diagnostic mutation screening protocol for skeletal dysplasias.

Cranio-osteoarthropathy in sibs.

Primary hypertrophic osteoarthropathy is a condition characterized by clubbing, arthropathy and periostosis of long tubular bones. Three variants of primary hypertrophic osteoarthropathy are distinguished: pachydermoperiostosis, which shows as additional symptom pachydermia; cranio-osteoarthropathy, which has a decreased neurocranium ossification as additional feature; and a secondary form. Primary hypertrophic osteoarthropathy is also genetically heterogeneous, with evidence for both autosomal dominant and autosomal recessive inheritance. We describe two sibs with cranio-osteoarthropathy and briefly review previously reported cases. The present cases demonstrate the phenotypic variability of the condition. The consanguinity in the present family and analysis of previously described cases support autosomal recessive inheritance for cranio-osteoarthropathy.

A form of autosomal dominant spondyloepiphyseal dysplasia is caused by a glycine to alanine substitution in the COL2A1 gene.

We report a family with an unusual form of autosomal dominant spondyloepiphyseal dysplasia characterized by infantile-onset disproportionate short stature with relative shortening of the spine, thoracic kyphosis, lumbar lordosis, scoliosis and premature osteoarthritis of the joints especially of the hips. Radiological findings include mild platyspondyly, vertebral end plate irregularity, irregular femoral necks, and dysplasia of the capital femoral epiphyses with flattening and irregularity present from childhood and mild variable epiphyseal dysplasia elsewhere in the skeleton. Intrafamilial variability is observed in the degree of short stature, severity of spinal and hip involvement and the age of onset of symptoms and complications. We demonstrate that this dysplasia is due to a glycine to alanine substitution in the COL2A1 gene (p.Gly862Ala), thereby expanding the phenotypic spectrum of dysplasias associated with defects in type II collagen.

Are stem cell characteristics altered by disease state?

Autologous stem cell transplantation combined with gene therapy can potentially be used to treat genetically inherited diseases. However, characterization of multipotential cells from a disease state remains extremely limited. We have characterized adult bone marrow stromal cells (MSCs) derived from three retinal degenerative mouse models and compared them to marrow stromal cells derived from their normal strain counterparts. Despite similar profiles soon after harvest, at 30 days postisolation, marrow stromal cells derived from a disease origin were shown to contain a large pool (approximately 89-99%) of undifferentiated marrow stromal cells (CD90(+)/STRO-1(+)) as compared to their normal counterparts (approximately 19-43%). Fetal bovine serum appeared essential for marrow stromal cell proliferation and was not found to induce differentiation, although it could be substituted with other additives including epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and leukemia inhibitory factor (LIF). We also showed that resulting CD90(+)/STRO(+) cells derived from both states could be directed into desired lineages expressing at the same rate and that they could be transduced with the same efficiency using different viral vehicles. This investigation has shown the existence of a large pool of undifferentiated stem cells derived from the disease state that have the potential to form the desired cell types when appropriately cued.

A new familial case of spondylo-epi-metaphyseal dysplasia with multiple dislocations Hall type (leptodactylic form).

We report a father and son affected by spondylo-epi-metaphyseal dysplasia with multiple dislocations (Hall type), also called leptodactylic form. This family contributes to the delineation of the clinical and radiological phenotype of this rare condition.

International nosology and classification of constitutional disorders of bone (2001).

The last International Classification of Constitutional Disorders of Bone was published in 1998. Since then rapid advances have been made in identifying the molecular changes responsible for defined conditions and new disorders are constantly being delineated. For these reasons a further update on the classification is appropriate. It has been expended to not only the osteochondrodysplasias (33 groups) but also genetically determined dysostoses (3 groups).

Diagnostic dilemmas in the short rib-polydactyly syndrome group.

The short rib-polydactyly syndromes are a group of lethal skeletal dysplasias with autosomal recessive inheritance characterized by markedly short ribs, short limbs, usually polydactyly, and multiple anomalies of major organs. At least four types have been recognized. The radiological findings of 10 cases are presented. Each fetus or stillbirth has some of the radiological features of the four established types of short rib-polydactyly syndrome and raises diagnostic dilemmas in differentiating these entities. The overlapping phenotypes of these fetuses supports the previously suggested hypothesis that the different subtypes of the short rib-polydactyly syndrome group are not single entities, but rather part of a continuous spectrum with variable expressivity.