Mutations in DYNC2H1, the cytoplasmic dynein 2, heavy chain 1 motor protein gene, cause short-rib polydactyly type I, Saldino-Noonan type.

The short-rib polydactyly syndromes (SRPS) are autosomal recessively inherited, genetically heterogeneous skeletal ciliopathies. SRPS phenotypes were historically categorized as types I-IV, with type I first delineated by Saldino and Noonan in 1972. Characteristic findings among all forms of SRP include short horizontal ribs, short limbs and polydactyly. The SRP type I phenotype is characterized by a very small thorax, extreme micromelia, very short, poorly mineralized long bones, and multiple organ system anomalies. To date, the molecular basis of this most severe type of SRP, also known as Saldino-Noonan syndrome, has not been determined. We identified three SRP cases that fit the original phenotypic description of SRP type I. In all three cases, exome sequence analysis revealed compound heterozygosity for mutations in DYNC2H1, which encodes the main component of the retrograde IFT A motor, cytoplasmic dynein 2 heavy chain 1. Thus SRP type I, II, III and asphyxiating thoracic dystrophy (ATD), which also result from DYNC2H1 mutations. Herein we describe the phenotypic features, radiographic findings, and molecular basis of SRP type I.

Abnormalities of the upper extremities on fetal magnetic resonance imaging.

OBJECTIVE: In view of the increasing use of fetal magnetic resonance imaging (MRI) as an adjunct to prenatal ultrasonography, we sought to demonstrate the visualization of upper extremity abnormalities and associated defects on MRI, with regard to fetal outcomes and compared with ultrasound imaging. METHODS: This retrospective study included 29 fetuses with upper extremity abnormalities visualized with fetal MRI following suspicious ultrasound findings and confirmed by postnatal assessment or autopsy. On a 1.5-Tesla unit, dedicated sequences were applied to image the extremities. Central nervous system (CNS) and extra-CNS anomalies were assessed to define extremity abnormalities as isolated or as complex, with associated defects. Fetal outcome was identified from medical records. MRI and ultrasound findings, when available, were compared. RESULTS: Isolated upper extremity abnormalities were found in three (10.3%) fetuses. In 26 (89.7%) fetuses complex abnormalities, including postural extremity disorders (21/26) and structural extremity abnormalities (15/26), were demonstrated. Associated defects involved: face (15/26); musculoskeletal system (14/26); thorax and cardio/pulmonary system (12/26); lower extremities (12/26); brain and skull (10/26); and abdomen (8/26). Of the 29 cases, 18 (62.1%) pregnancies were delivered and 11 (37.9%) were terminated. MRI and US findings were compared in 27/29 cases: the diagnosis was concordant in 14 (51.9%) of these cases, and additional findings were made on MRI in 13/27 (48.1%) cases. CONCLUSIONS: Visualization of upper extremity abnormalities on fetal MRI enables differentiation between isolated defects and complex ones, which may be related to poor fetal prognosis. MRI generally confirms the ultrasound diagnosis, and may provide additional findings in certain cases.

Pachydermoperiostosis: an update.

Pachydermoperiostosis (PDP) is a rare genodermatosis, characterized by pachydermia, digital clubbing, periostosis and an excess of affected males. Although an autosomal dominant model with incomplete penetrance and variable expression has been proved, both autosomal recessive and X-linked inheritance have been suggested. However, at present, genetic heterogeneity is not fully supported. The aim of this study is to review the clinical and pedigree data of 68 published PDP families, including 204 patients. This analysis has confirmed an autosomal dominant mutation in 37 families and suggested the existence of an autosomal recessive form in the remaining families. The two forms may differ in clinical severity, intrafamilial variability and prevalence of some features. Additionally, the marked skewed sex ratio could not be easily explained by an X-linked mutation, but alternative explanations (i.e. testosterone promoting proliferation) are discussed.

Diagnostic value of radiography in cases of perinatal death: a population based study.

OBJECTIVE: To examine the yield of radiographic abnormalities in a population based set of perinatal deaths, the diagnostic value of whole body postmortem radiographs in the same set, and previous factors that may increase the proportion of useful examinations. DESIGN: Retrospective population based study. SETTING: A region of Norway. PATIENTS: All infants from a well defined geographical area who were stillborn or had died soon after birth over an 11 year period (n=542), who had routinely undergone whole body radiography and autopsy. MAIN OUTCOME MEASURES: (a) Proportion of cases with abnormal radiographic findings. (b) Proportion of abnormal radiographs providing new information that was useful for postmortem diagnosis. RESULTS: Radiographs were abnormal in 162/542 cases (30%). These provided new information about, but did not help to confirm, the pathological process leading to death in 14/162 (8.6%), may have helped to confirm, but not establish, the cause(s) of death in 1/162 (0.6%), and were of vital importance for establishing the cause(s) of death in 5/162 (3.1%). Among infants with external malformations, the proportion of useful radiographs was 12/100 (12%), and among the remainder it was 8/436 (1.8%), a difference of 10.2% (95% confidence interval 3.7% to 16.7%; data missing for six cases). CONCLUSIONS: The diagnostic value of postmortem radiography in this population based set was low. However, radiographic findings were of vital importance for establishing the cause(s) of death in 5/542 cases (0.9%).

Double heterozygosity for pseudoachondroplasia and spondyloepiphyseal dysplasia congenita.

Pseudoachondroplasia (PSACH) and spondyloepiphyseal dysplasia congenita (SEDC) are autosomal dominant forms of short-limb short stature caused by mutations in genes that encode structural components of the cartilage extracellular matrix. PSACH results from mutations in the cartilage oligomeric matrix protein (COMP) gene, while SEDC is caused by mutations in the gene for type II procollagen (COL2A1). We report a child with a distinct skeletal dysplasia due to the combined phenotypes of PSACH and SEDC. The proband's mother had PSACH and his father had SEDC. The child was suspected of having both phenotypes on the basis of the severity of his clinical and radiographic findings, and this was confirmed by molecular analysis. The COMP gene mutation (C348R), while not previously published, is typical of those in PSACH patients, whereas the COL2A1 mutation (T1370M) is somewhat atypical, as it predicts an amino acid change within the carboxyl-terminal region of the protein. Both mutations segregated with their respective phenotypes within this family. The description and natural history of the double heterozygote phenotype may be useful in counseling families regarding risk and prognosis.

Characterization of a long-term survivor with Stüve-Wiedemann syndrome and mosaicism of a supernumerary marker chromosome.

Stüve-Wiedemann syndrome (SWS) is typically lethal in the neonatal period; only two patients have been reported with a longer survival. We report a new patient with SWS, who at 9 years of age is one of the longest survivors with this disorder. In addition to the characteristic features of SWS, she has a number of unique clinical signs, including lack of corneal and patellar reflexes, a smooth tongue with no fungiform papillae, chronic gingival abscesses, mottled, poor dentition, blotchy pigmentation of the skin, unusual infections, multiple fractures, and progressive scoliosis. Cytogenetic analysis identified mosaicism for a supernumerary marker chromosome (SMC), seen in the majority of amniocytes, blood, and skin fibroblasts. The SMC was shown to be derived from chromosome 5 and contains euchromatin. The significance of the SMC to the etiology of SWS is unknown. This patient further demonstrates that SWS is not universally lethal.

Subtle radiographic findings of achondroplasia in patients with Crouzon syndrome with acanthosis nigricans due to an Ala391Glu substitution in FGFR3.

A unique type of craniofacial dysostosis, Crouzon syndrome with acanthosis nigricans (CAN), has been attributed to a specific substitution (Ala391Glu) in the fibroblast growth factor receptor 3 (FGFR3) gene. At birth, individuals with this disorder have craniosynostosis, ocular proptosis, midface hypoplasia, choanal atresia, hydrocephalus, and they experience the onset of acanthosis nigricans during childhood. We report three cases and compare the clinical characteristics of our cases with the previously reported cases of this disorder. Since the Ala391Glu substitution in FGFR3 is close to the substitutions in the transmembrane domain that result in achondroplasia, we carefully reviewed the skeletal findings in six patients. We identified subtle radiographic findings of achondroplasia in all six cases including narrow sacrosciatic notches, short vertebral bodies, lack of the normal increase in interpediculate distance from the upper lumbar vertebrae caudally, and broad, short metacarpals and phalanges. Even before acanthosis nigricans appears, the presence of choanal atresia and hydrocephalus in an individual with features of Crouzon syndrome should suggest the diagnosis of CAN, and subtle skeletal findings can lend further support to this diagnosis.

"Baby rattle" pelvis dysplasia.

We report an apparently previously undescribed lethal skeletal dysplasia, clinically resembling achondrogenesis, but with distinct radiologic and chondro-osseous morphologic features. These comprise bifid distal ends of the long bones of the limbs, absent vertebral body ossification, a unique "baby rattle" pelvic configuration with tall and broad ilia, absent endochondral ossification, regions of mesenchymal cells within the resting cartilage, and abnormal mesenchymal ossification.

Progressive erosive arthropathy with contractures, multicentric osteolysis-like changes, characteristic craniofacial appearance, and dermatological abnormalities: a new syndrome?

We report a 27-year-old man with an apparently new syndromic form of progressive erosive arthropathy and contractures of small and large joints associated with mild epiphyseal changes, normal vertebrae, and generalized osteopenia. The patient had a characteristic craniofacial appearance, dermatological abnormalities, and normal intelligence. The head was large with frontal bossing. The face was elongated with malar hypoplasia, thin upper lip, prominent lower jaw, high arched palate, dental malocclusion, and prominent ears with absent ear lobules. Dermatological abnormalities included malar erythema and facial telangiectasia together with multiple nevi and lentigenes all over the body. Pseudorheumatoid arthropathy, spondyloarthropathy, and Borrone dermatocardioskeletal syndrome were considered in the differential diagnosis and were excluded. Also, no similar cases have been found in POSSUM or the London Dysmorphology databases.

Multiple epiphyseal dysplasia: radiographic abnormalities correlated with genotype.

Multiple epiphyseal dysplasia (MED) is an osteochondrodysplasia characterized clinically by mild short stature and early-onset degenerative joint disease and radiographically by epiphyseal hypoplasia/dysplasia. MED is genetically heterogeneous, with autosomal dominant cases resulting from mutations in at least three genes: the cartilage oligomeric matrix protein (COMP) gene (EDM1) and the COL9A2 (EDM2) and COL9A3 (EDM3) genes of type IX procollagen. We present here a comparison of the radiographic phenotypes of MED patients with type IX collagen gene mutations and those with COMP gene mutations. We reviewed radiographs from two patients with MED produced by COMP mutations, two families with COL9A2 mutations, and one family with a mutation in COL9A3. The data demonstrated that the patients with type IX collagen defects had more severe joint involvement at the knees and relative hip sparing, while the patients with COMP mutations had significant involvement at the capital femoral epiphyses and irregular acetabuli. This pattern of joint involvement was consistent regardless of overall degree of severity of the phenotype.

Radiographic findings and Gs-alpha bioactivity studies and mutation screening in acrodysostosis indicate a different etiology from pseudohypoparathyroidism.

Acrodysostosis is an uncommon skeletal dysplasia associated with nasal hypoplasia, midface deficiency, severe brachydactyly, and varying degrees of hearing loss and mental retardation. Previous publications have suggested that it may be difficult to distinguish acrodystostosis from pseudohypoparathyroidism on clinical grounds, but acrodysostosis does appear to have distinct clinical and radiologic findings. Spinal stenosis is an underappreciated risk in acrodysostosis, despite the reported loss of normal caudal widening of the lumbar interpediculate distance on AP spine radiographs in the original report of this disorder by Robinow et al., with confirmation of these radiographic findings by Butler et al. We report two sporadic cases of acrodysostosis, one of which required decompressive laminectomy for symptomatic spinal stenosis, and review 11 cases of acrodysostosis from 9 families that were submitted to the International Skeletal Dysplasia Registry. The objective of this report is to determine the frequency and severity of spinal stenosis in patients with acrodysostosis and to summarize the clinical and radiographic findings of acrodysostosis in an effort to distinguish acrodysostosis clearly from pseudohypoparathyroidism. The pattern of brachydactyly differs between these two conditions, and varying degrees of spinal stenosis are characteristic of acrodysostosis. Both our index patients with acrodysostosis had normal bioactivity of the alpha subunit of the Gs protein, therefore indicating that acrodysostosis has a different pathogenesis from pseudohypoparathyroidism. Furthermore, single-strand confirmational polymorphism (SSCP) analysis failed to demonstrate any confirmational alterations in the coding exons of the Gs alpha gene. These radiographic and laboratory findings substantiate that acrodysostosis is clinically different from pseudohypoparathyroidism and that it is necessary to follow patients with acrodysostosis for signs of spinal stenosis.

A new form of spondyloperipheral dysplasia with facial dysmorphism, flattened vertebrae, hypoplastic pelvis, brachydactyly and soft tissue syndactyly.

We report the case of a 9-year-old Japanese boy with spondyloperipheral skeletal dysplasia associated with facial dysmorphism, pelvic abnormalities, and distinctive hands and feet. Radiographic manifestations included mild platyspondyly with posterior scalloping, small flared ilia with shallow acetabulae, mesomelic shortening of long bones, marked delay of carpal bone maturation, and brachydactyly with hypoplastic middle and terminal phalanges bilaterally in both hands and feet. There was bilateral soft tissue syndactyly of the 2nd and 3rd interdigital spaces of the hands, the 2nd interdigital space of the feet, with hypoplastic nails. The clinical and radiographic manifestations in this case appear to represent a unique type of skeletal dysplasia.

Asynchronous asymmetric form of heterogeneous osteopetrosis: initial case expanded and a new case.

We have discovered additional serial radiographs and clinical information on the initial case of "regional osteopetrosis tarda" that has been included in several editions of Caffey's Pediatric X-Ray Diagnosis. A definite second case was found after a search of radiology teaching files of other selected medical centers and the International Skeletal Dysplasia Registry. Analysis of the sequential unusual radiographic findings of the initial case and the equivalent compelling findings of the second case justifies renewed attention to an asynchronous asymmetric form of heterogeneous osteopetrosis.

"Duplicate calcaneus": a rare developmental defect observed in several skeletal dysplasias.

Duplication of the calcaneus is a rarely observed radiographic finding that probably results from delayed coalescence of two primary calcaneal centers of ossification. We performed a review of 2,500 computerized cases of skeletal dysplasias and syndromes with bone involvement in the International Skeletal Dysplasia Registry, searching for those cases in which a duplicate calcaneus had been recorded. We found that it was a non-random feature of three skeletal dysplasias and groups comprising thanatophoric dysplasia and the chondrodysplasia punctata and short rib (polydactyly) groups. We conclude that duplication of the calcaneus should be considered a consistent feature of these entities and may reflect a more generalized developmental defect.

Oto-palato-digital syndrome, type II: report of three cases with further delineation of the chondro-osseous morphology.

Oto-palato-digital syndrome type II (OPD II) is a lethal X-linked skeletal dysplasia with pleiotropic manifestations. The basic defect is not known. There has been only one detailed report of the chondro-osseous abnormalities in this condition describing abnormal periosteal ossification in a single case [1990: Am J Med Genet 36:226-231]. We report on three cases of OPD II emphasizing the chondro-osseous morphology. Although endochondral ossification was normal, periosteal ossification was defective with islands of cortical bone aplasia and hyperplasia of the periosteum. The trabecular bone was also extremely poorly formed and markedly hypercellular. Both membranous ossification and bone remodeling appear to be defective in OPD II and should account for part of the observed phenotype. The biglycan gene maps to Xq28 and is involved in bone formation, but was excluded as a candidate by direct sequencing of cDNA in one case.

Uruguay facio-cardio-musculo-skeletal syndrome: a novel X-linked recessive disorder.

We report on three male patients from a single family with a brachyturricephaly, "pugilistic" facial appearance, a muffled voice, cardiomyopathy, muscular hypertrophy, broad hands, wide feet with progressive pes cavus deformities, dislocation of toes, variable congenital hip dislocation, and scoliosis. Three other males in the family, now deceased from cardiac disease, appear to have had the same disorder. The mother of the propositus has milder signs of the syndrome. All affected males are related through the maternal line. These cases represent an apparently previously undescribed X-linked recessive syndrome.

New mesomelic dysplasia with absent fibulae and triangular tibiae.

We report on two unrelated, sporadic cases of a mesomelic dysplasia characterized by absence of fibulae and severely hypoplastic, triangular-shaped tibiae. Moderate mesomelic shortness was present in the upper limbs with proximal widening of the ulnae. There was also axial skeletal involvement in both cases, characterized radiographically by an abnormal pelvis and marked bilateral glenoid hypoplasia. These cases appear to represent a new form of mesomelic dysplasia distinct from those previously delineated.

Schmid type metaphyseal chondrodysplasia: a spondylometaphyseal dysplasia identical to the "Japanese" type.

BACKGROUND: Schmid-type metaphyseal chondrodysplasia (Schmid MCD) is an autosomal dominant chondrodysplasia resulting from various mutations in the COL10A1 gene. This disorder has been well delineated at a clinical level and has been classified radiographically as a pure metaphyseal chondrodysplasia. A missense mutation in the COL10A1 gene has also been shown to cause a rare spondylo-metaphyseal chondrodysplasia (SMD) named the "Japanese" type which, apart from exhibiting a mild spinal phenotype, shares striking clinical and radiographic similarities to Schmid MCD. OBJECTIVE: The clinical, radiographic and molecular similarities between Schmid MCD and Japanese SMD led to the hypothesis that these conditions could be identical type X collagenopathies. MATERIALS AND METHODS: We analyzed 33 cases of typical Schmid MCD from the International Skeletal Dysplasia Registry, looking specifically for any radiographic evidence of spinal involvement. RESULTS: We found that in 9.1% (3/33) of cases reviewed there was definite radiographic evidence of spinal involvement comprising mild platyspondyly, vertebral body abnormalities, and end-plate irregularity. CONCLUSION: These data indicate that spinal changes are an uncommon but variable component of Schmid MCD and that this condition and "Japanese" SMD are identical collagen type X disorders. Furthermore, the fact that the specific mutation reported in the family with Japanese type SMD, resulting in the substitution of a glutamic acid residue for a glycine at codon 595 (G595 E), has also been reported in a patient with Schmid MCD strongly supports this conclusion.

Report of five novel and one recurrent COL2A1 mutations with analysis of genotype-phenotype correlation in patients with a lethal type II collagen disorder.

Achondrogenesis II-hypochondrogenesis and severe spondyloepiphyseal dysplasia congenita (SEDC) are lethal forms of dwarfism caused by dominant mutations in the type II collagen gene (COL2A1). To identify the underlying defect in seven cases with this group of conditions, we used the combined strategy of cartilage protein analysis and COL2A1 mutation analysis. Overmodified type II collagen and the presence of type I collagen was found in the cartilage matrix of all seven cases. Five patients were heterozygous for a nucleotide change that predicted a glycine substitution in the triple helical domain (G313S, G517V, G571A, G910C, G943S). In all five cases, analysis of cartilage type II collagen suggested incorporation of the abnormal alpha1(II) chain in the extracellular collagen trimers. The G943S mutation has been reported previously in another unrelated patient with a strikingly similar phenotype, illustrating the possible specific effect of the mutation. The radiographically less severely affected patient was heterozygous for a 4 bp deletion in the splice donor site of intron 35, likely to result in aberrant splicing. One case was shown to be heterozygous for a single nucleotide change predicted to result in a T1191N substitution in the carboxy-propeptide of the proalpha1(II) collagen chain. Study of the clinical, radiographic, and morphological features of the seven cases supports evidence for a phenotypic continuum between achondrogenesis II-hypochondrogenesis and lethal SEDC and suggests a relationship between the amount of type I collagen in the cartilage and the severity of the phenotype.

Pathological fractures in spondyloenchondrodysplasia: case report.

We present a patient with spondyloenchondrodysplasia who sustained two pathological fractures of long bones in a period of 6 months. This complication of spondyloenchondrodysplasia has not been described previously. Since both fractures occurred with mild trauma, it would appear that spondyloenchondrodysplasia can be associated with a tendency towards pathological fractures and, therefore, it would be advisable to warn people suffering from this condition to avoid activities that put excessive strain on the limbs.