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Autosomal recessive omodysplasia (GPC6-related) is a rare short-limb skeletal dysplasia caused by biallelic mutations in the GPC6 gene. Affected individuals manifest with rhizomelic short stature, decreased mobility of elbow and knee joints as well as craniofacial anomalies. Both upper and lower limbs are severely affected. These manifestations contrast with normal height and limb shortening restricted to the arms in autosomal dominant omodysplasia (FZD2-related). Here, we report 2 affected brothers of Pakistani descent from Denmark with GPC6-related omodysplasia, aiming to highlight the clinical and radiological findings. A homozygous deletion of exon 6 in the GPC6 gene was detected. The pathognomonic radiological findings were distally tapered humeri and femora as well as severe proximal radioulnar diastasis. On close observations, we identified a recurrent and not previously described type of abnormal patterning in all long bones.

We described a heterozygous de novo mutation (G434V) in the frizzled class receptor 2 (FZD2) gene in a patient with distinct facial features including hypertelorism, bilateral cleft lip/palate, short nose with a broad nasal bridge, microretrognathia, and bilateral shortness of the upper limbs, first metacarpal bones, and middle phalanges of the 5th digits. The findings of our patient were compared to an autosomal dominant omodysplasia (OMOD2) family with FZD2 mutation reported in the literature. OMOD2 is a rare skeletal dysplasia and characterized by facial dysmorphism and shortness of the upper extremities and first metacarpal bones. This is the second report which supports the findings of the first family described and points out that heterozygous FZD2 mutations may be disease-causing for OMOD2.

Autosomal dominant omodysplasia is a rare skeletal dysplasia characterized by short humeri, radial head dislocation, short first metacarpals, facial dysmorphism and genitourinary anomalies. We performed next-generation whole-exome sequencing and comparative analysis of a proband with omodysplasia, her unaffected parents and her affected daughter. We identified a de novo mutation in FRIZZLED2 (FZD2) in the proband and her daughter that was not found in unaffected family members. The FZD2 mutation (c.1644G>A) changes a tryptophan residue at amino acid 548 to a premature stop (p.Trp548*). This altered protein is still produced in vitro, but we show reduced ability of this mutant form of FZD2 to interact with its downstream target DISHEVELLED. Furthermore, expressing the mutant form of FZD2 in vitro is not able to facilitate the cellular response to canonical Wnt signaling like wild-type FZD2. We therefore conclude that the FRIZZLED2 mutation is a de novo, novel cause for autosomal dominant omodysplasia.

Omodysplasia-2 (OMOD2; OMIM%16475) is a rare autosomal dominant (AD) skeletal dysplasia characterized by shortened humeri, short first metacarpal, craniofacial dysmorphism (frontal bossing, depressed nasal bridge, bifid nasal tip, and long philtrum), and variable degrees of genitourinary anomalies. This clinical phenotype overlaps with that of AD type Robinow syndrome. Recently, a mutation in FZD2 encoding a Frizzled Class Receptor 2 has been identified in a family with AD omodysplasia (an affected girl and her affected mother). Here, we present the second report on a heterozygous novel nonsense FZD2 mutation in OMOD2 or Robinow syndrome-like phenotype. The proband was a 16-year-old boy, who has been followed from infancy to adolescence. He presented with rhizomelic short stature with elbow restriction, mild facial dysmorphism (depressed broad bridge, short nose, anteverted nostrils, long philtrum, and low-set ears), and genital hypoplasia. Radiological examination in infancy showed short, broad humeri with relatively narrow distal ends, mildly broad femora, thick proximal ulnae with hypoplastic, dislocated proximal radii, and short first metacarpals. The abnormal skeletal pattern was persistent in adolescence; however, the humeri and femora became less undermodeled, while the humeri and radii became mildly bowed. Molecular analysis identified a de novo, heterozygous, nonsense mutation (c.1640C>A, p.S547*) in FZD2. The affected codon was next to the previously reported mutation (p.Trp548*). The results indicate that OMOD2 or Robinow syndome-like phenotype can be caused by a heterozygous nonsense FZD2 mutation impairing Wnt signaling. Further molecular studies will permit better clarification of the phenotypic spectrum in patients with OMOD2.

We report on the natural history of a female with dominant omodysplasia, a rare osteochondrodysplasia with short stature, rhizomelia of the extremities (upper extremities more affected), and short first metacarpals. The proband had normal molecular analysis of the glypican 6 gene (GPC6), which was recently reported as a candidate for autosomal recessive omodysplasia. The findings in this patient were compared to other known and suspected cases of autosomal dominant omodysplasia. Mild rhizomelic shortening of the lower extremities has not been previously reported. © 2014 Wiley Periodicals, Inc.

Autosomal recessive omodysplasia (ARO), a rare congenital skeletal dysplasia, is characterized by micromelia and craniofacial anomalies. Upper and lower limbs are affected in contrast to the dominant form in which the lower limbs are normal. Radiographic features include shortening and distal tapering of the humerus and femur, proximal radioulnar diastasis, and anterolateral radial head dislocation. We present a recurrence of ARO in a family, detected on prenatal ultrasound at 13 weeks of gestation. Chromosome analysis of the products of conception and the affected sibling showed a paternally-inherited paracentric inversion of 15q13 to q21.3. Due to similarities in the clinical phenotype between diastrophic dysplasia and this condition, testing for DTDST mutation was performed with no mutation detected.

Congenital dysplasia of the humerus is very rare. It is characteristically seen in omodysplasia and has also been reported as one of the associated features of Larsen's syndrome. We report a 4-year-old girl with bilateral humero-ulnar dysplasia, with dislocation of the elbows, facial dysmorphism, ball-and-socket ankles and foot deformities. Although the elbow dysplasia is similar to that seen in Larsen's syndrome, other pathognomic features of Larsen's syndrome were absent. The changes seen in the elbows in this patient are also different from those encountered in omodysplasia. We believe that this condition may be a distinct form of skeletal dysplasia hitherto undescribed.

Second-semester ultrasonography of a female fetus documented short femora and humeri and dislocation of the radii. Based on the clinical and postmortem radiological findings, autosomal-recessive omodysplasia was diagnosed. The physeal plates of the long tubular bones were assessed by computer-assisted image analysis. The dimensions and orientation of the chondrocytic lacunae in the physeal plates of the omodysplastic fetus were compared with those in the physeal plates of fetuses without gross limb abnormalities (oligohydramnios, n = 2; hydrocephalus, n = 2; Down syndrome, n = 1). The pathological characteristics of the omodysplastic physeal plates were an expanded zone of proliferating cartilage and an increased number of closely packed, small chondrocytes. We propose that a genetic, functional deficiency of the physeal cells, underlying the short-limbed dwarfism of autosomal-recessive omodysplasia, is partially compensated, albeit ineffectively, by an increased number of small chondrocytes in the proliferating zone of the physeal plate.

Chapter 61 covers omodysplasia, autosomal recessive (MIM 258315, 251455, 268250), including major clinical findings, radiographic features, and differential diagnoses.

Recently Maroteaux et al. [Am J Med Genet 32:371-375] described omodysplasia as a new distinct congenital bone disorder in 3 cases; autosomal dominant inheritance was suggested. In this same report, 2 other cases (patients 4 and 5) presented with the same facial and upper limb anomalies, but were also noted to have severe shortness of lower limbs. The authors considered all 5 cases to represent variable expressivity of the same disorder, namely, omodysplasia. Here we report 4 patients (3 survivors), offspring of consanguineous Arabic-Moslem couples. All presented at birth with severe short limb dwarfism and facial and radiologic appearance quite distinct from the first 3 patients of Maroteaux et al. [1989] with so-called omodysplasia. Thus, we suggest that our 4 cases and patients 4 and 5 of Maroteaux et al. [1989] represent a distinct, previously unpublished bone dysplasia.

We describe a second family with mother to son transmission of omodysplasia, a rare skeletal dysplasia characterized by shortened humeri, shortened first metacarpals and craniofacial dysmorphism. The mother in this family had been diagnosed previously with Robinow syndrome; subsequently, her diagnosis was reclassified. Her pregnancy was closely monitored antenatally with serial ultrasound examinations. Delayed ossification of the humerus was noted prenatally. Her son had ambiguous genitalia and similar skeletal manifestations as his mother. A comparison to other known and suspected cases of dominant omodysplasia is presented. Our observations confirm the existence of a dominant variant of omodysplasia, document genital hypoplasia as an important feature of this syndrome in males and highlight the need to differentiate this entity from Robinow syndrome.

Two sibs with omodysplasia were born to phenotypically normal but consanguineous parents. They had severe micromelic dwarfism, facial anomalies, and mental retardation. One had a congenital heart defect. The radiographic findings are typical: hypoplastic distal end of the humerus with radioulnar diastasis. Parental consanguinity and clinical manifestations in 2 sibs suggest autosomal recessive inheritance. © 1994 Wiley-Liss, Inc.