CHN1 and duane retraction syndrome: Expanding the phenotype to cranial nerves development disease.

Duane retraction syndrome is a congenital eye movement disorder characterized by a failure of abducens nerve to develop normally, resulting in restriction or absence of abduction, adduction, or both, and narrowing of the palpebral fissure and retraction of the globe on attempted adduction. There is a genetic heterogeneity in Duane retraction syndrome (DURS). DURS maps to chromosome 8q13 in some patients, and pathogenic variants in CHN1 and MAFB genes are known to lead to DURS. We report here a child and his father with Duane retraction syndrome, associated to swallowing difficulties and unilateral trapeze aplasia. A whole exome sequencing revealed a heterozygous missense variant in CHN1 gene. This gene encodes GTPase-activating protein and is involved in the assembly of neuronal locomotor circuits. A patient with a 8q deletion has previously been described with a Duane retraction syndrome associated to trapeze aplasia. We provide an additional description to support the role in cranial nerves development of the CHN1 gene.

Oculo-Auriculo-Fronto-Nasal Syndrome With Duane Retraction Syndrome and Dysplastic Bony Structure in the Midline of Nose.

Oculo-auriculo-fronto-nasal syndrome (OAFNS) is a rare anomaly characterized by features overlapping those of frontonasal dysplasia (FND) and the oculo-auriculo-vertebral spectrum (OAVS). The FND features malformation of frontonasal process-derived structures, characterized by anomalies in the central portion of the face. The OAVS is characterized by developmental anomalies of the first and second pharyngeal arches. The OAFNS is a condition with clinical features of both FND and OAVS.Here, the authors present the case of a male with OAFNS who not only exhibited typical OAFNS symptoms but also a dysplastic bony structure that bridged the anterior nasal spine and inferior nasal bones, and unilateral type 3 Duane retraction syndrome (absence of right-eye abduction). Abnormal nasal bones are characteristic of OAFNS; such abnormalities are absent from FND and OAVS. The authors reduced the dysplastic nasal bony structure via open external rhinoplasty, followed by lateral nasal osteotomy when he was 16 years of age. The nasal dorsum appeared natural after surgery and he was satisfied with the result.

Diffusion Tensor Imaging of the Lateral Rectus Muscle in Duane Retraction Syndrome.

AIM: This study aimed to assess metrics of diffusion tensor imaging in evaluating microstructural abnormalities of the lateral rectus muscle in Duane retraction syndrome (DRS). PATIENT AND METHODS: A prospective study was conducted on 27 patients with DRS and 16 age- and sex-matched controls who underwent diffusion tensor imaging of orbit and forced duction test (FDT). Fractional anisotropy (FA) and mean diffusivity (MD) of the lateral rectus were calculated by 2 observers. RESULTS: Fractional anisotropy of the lateral rectus in patients (0.62 ± 0.07 and 0.59 ± 0.06) was significantly higher (P = 0.001) than that in controls (0.49 ± 0.06 and 0.51 ± 0.06). Selection values of 0.53 and 0.52 as cutoff points of FA of the lateral rectus to differentiate patients from controls revealed areas under the curve of 0.92 and 0.86 and accuracy values of 84.8% and 80.4% by both observers, respectively. Mean diffusivity of the lateral rectus by both observers in patients (1.19 ± 0.13 and 1.23 ± 0.19 × 10 mm/s) was significantly lower (P = 0.001) than that in controls (1.54 ± 0.18 and 1.49 ± 0.16 × 10 mm/s). Selection values of 1.35 and 1.40 × 10 mm/s as cutoff points of MD of the lateral rectus to differentiate patients from the control groups revealed areas under the curve of 0.93 and 0.85 and accuracy values of 91.3% and 80.4% by both observers, respectively. Interobserver agreement for MD and FA of the lateral rectus by both observers were excellent (r = 0.870 and, 0.959). Diffusion tensor imaging metrics of the lateral rectus muscle did not differ significantly between patients with unilateral and bilateral disease (P = 0.05) and patients with DRS type I and type III (P = 0.05). Diffusion tensor imaging metrics of the lateral rectus muscle differed significantly between FDT grades I and II versus grades III and IV, and these metrics were well correlated with the degree of FDT. CONCLUSION: Diffusion tensor imaging metrics are valuable noninvasive tools in evaluating the microstructural abnormalities of the lateral rectus in DRS and are well correlated with degree of FDT.

Abducens Nerve in Patients with Type 3 Duane's Retraction Syndrome.

BACKGROUND: We have previously reported that the presence of the abducens nerve was variable in patients with type 3 Duane's retraction syndrome (DRS), being present in 2 of 5 eyes (40%) and absent in 3 (60%) on magnetic resonance imaging (MRI). The previous study included only 5 eyes with unilateral DRS type 3. OBJECTIVES: To supplement existing scarce pathologic information by evaluating the presence of the abducens nerve using high resolution thin-section MRI system in a larger number of patients with DRS type 3, thus to provide further insight into the pathogenesis of DRS. DATA EXTRACTION: A retrospective review of medical records on ophthalmologic examination and high resolution thin-section MRI at the brainstem level and orbit was performed. A total of 31 patients who showed the typical signs of DRS type 3, including abduction and adduction deficit, globe retraction, narrowing of fissure on adduction and upshoot and/or downshoot, were included. The abducens nerve and any other extraocular muscle abnormalities discovered by MRI were noted. RESULTS: DRS was unilateral in 26 patients (84%) and bilateral in 5 patients (16%). Two out of 5 bilateral patients had DRS type 3 in the right eye and DRS type 1 in the left eye. Of the 34 affected orbits with DRS type 3 in 31 patients, the abducens nerve was absent or hypoplastic in 31 eyes (91%) and present in 3 eyes (9%). Patients with a present abducens nerve showed more limitation in adduction compared to patients with an absent abducens nerve (P = 0.030). CONCLUSIONS: The abducens nerve is absent or hypoplastic in 91% of DRS type 3. Patients with a present abducens nerve showed more prominent limitation of adduction. As DRS type 3 partly share the same pathophysiology with type 1 and 2 DRS, the classification of DRS may have to be revised according to MRI findings.

Transient pseudo-Duane syndrome after lateral orbital trauma.

Duane syndrome is a dysinnervation disorder that frequently involves secondary anomalous eye movement, in particular, ocular retraction and the narrowing of the palpebral fissure on the adduction. Pseudo-Duane syndrome is caused by a mechanical restriction that produces clinical findings similar to those of Duane syndrome. Most patients with pseudo-Duane syndrome have restrictive pathologies on the medial side of the globe, such as entrapment of the medial rectus muscle. We report the case of a 44-year-old man with pseudo-Duane syndrome in whom we identified a lateral orbital wall fracture and entrapment of the soft tissue surrounding the lateral rectus muscle by computed tomography. To the best of our knowledge, this etiology of pseudo-Duane syndrome has not been previously reported.

First-trimester prenatal diagnosis of Okihiro syndrome.

A case of Okihiro syndrome (OS) detected by 2- and confirmed by 3-dimensional ultrasound at 13+2 gestational weeks is reported. While the pregnant woman affected by the OS presented with limb anomalies, the fetus showed severe thoracoabdominal and skeletal anomalies. Termination of pregnancy was performed at 14+1 gestational weeks and confirmed the sonographically detected symptoms. The diagnosis was confirmed by autoptic, radiologic and molecular genetic analysis. To our knowledge, this is the first case of prenatal diagnosis of OS.

Bilateral Duane retraction syndrome with optic nerve hypoplasia.

The authors report a unique case of a child with the infrequent association of bilateral Duane retraction syndrome with underdevelopment of the anterior visual pathway. Both conditions were caused presumably due to a common disturbance of neuronal development during the second month of embryogenesis.

Chromosome 22 marker in a child with Duane syndrome and urogenital abnormalities.

The nature and the origin of de novo small marker chromosome found at prenatal diagnosis were determined by fluorescence in situ hybridization (FISH) using chromosome centromere-specific probes and by chromosome in situ suppression (CISS) using chromosome specific libraries. The small marker was characterized as being derived from chromosome 22. The fetus which exhibited a minichromosome had kidney malformations and after birth showed clinical features consistent with the Duane anomaly. One previous case with Duane anomaly and abnormalities of urogenital tract associated to a bisatellitated marker derived from chromosome 22 was reported. These findings indicate that a gene or genes located in the region of chromosome 22pter-->q11 may be associated with the Duane anomaly and the development of the urogenital tract.

Association of Duane retraction syndrome with craniofacial malformations.

Specific forms of ocular motor disturbances, such as Duane syndrome, occur with sufficient frequency in certain syndromes that the timing, location, and nature of the developmental disturbance may be established. The presence of this characteristic type of strabismus in a number of cases of hemifacial microsomia, especially the Goldenhar variants, may provide insight into the developmental disturbances of this large, complex group of patients. Evaluation of specific abnormalities of affected patients from the perspective of one discipline may further aid in the "lumping" or "splitting" process.

Wildervanck syndrome--the external appearance and radiologic findings.

Wildervanck syndrome is a combination of congenital anomalies characterized by deafness, Klippel-Feil deformity, and an unusual ocular motility disturbance called Duane retraction syndrome. This syndrome is seen infrequently in the general population and may not be recognized since the external appearance of the ears may be normal, and the unusual form of strabismus may not be obvious to the non-ophthalmologist. Patients with the full extent of this triad have a unique appearance. CT examination in these patients delineates the cervical anomalies as well as the inner ear deformity.