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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.

Autosomal dominant omodysplasia (OMOD2) is a rare skeletal dysplasia delineated and clinically differentiated from its autosomal recessive counterpart (OMOD1) by Maroteaux et al.1 OMOD2 is clinically characterized primarily by short upper extremities, with rhizomelic greater than mesomelic shortness, radial dislocation, short first metacarpals, facial dysmorphism, and genital anomalies. Additional features that have been variably reported include short stature, femoral anomalies, and vertebral anomalies. Saal et al2 recently described an alteration (c.1644G>A, p.Trp548*) in the FRIZZLED2 (FZD2) gene causative of OMOD2. Subsequently, there have been two additional reports of a novel missense alteration (c.1301G>T, p.Gly434Val) and a novel nonsense alteration (c.1640C>A, p.Ser547*) in the FZD2 gene associated with OMOD2.3, 4 The purposes of this report are to communicate the detection of the p.Trp548* FZD2 alteration in a previously described patient and to describe a new unrelated patient initially considered to have features more consistent with Robinow syndrome.

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 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.

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.