Rhombencephalosynapsis is a rare genetic  brain abnormality of malformation of the cerebellum. The cerebellar vermis is either absent or only partially formed, and fusion is seen in varying degree between the cerebellar hemispheres, fusion of the middle cerebellar peduncles, and fusion of the dentate nuclei. Findings range from mild truncal ataxia, to severe cerebral palsy.Rhombencephalosynapsis is a constantly found feature of Gomez-Lopez-Hernandez syndrome. One case of which has shown a co-occurrence with autism-spectrum disorder. Presentation
Clinical indications range from mild truncal ataxia with unaffected cognitive abilities, to severe cerebral palsy and intellectual disability. Genetics
An association with mutations in the MN1 gene has been reported in cases of atypical rhomboencephalosynapsis. Pathology
Rhombencephalosynapsis is a rare brain disorder of malformation of the cerebellum that may be detected on ultrasound of the fetus. The vermis is either absent or partially formed. There is dorsal fusion of the cerebellar hemispheres, fusion of the dentate nuclei, and fusion of the middle cerebellar peduncles. The degree of severity of this disorder is associated with the degree of maldevelopment of the cerebellar vermis.Aqueductal stenosis commonly exists with the disorder, as does its often resulting hydrocephalus. In some cases additional abnormalities may be present, such as ventriculomegaly (enlarged ventricles), and supratentorial abnormalities. Diagnosis
Rhombencephalosynapsis can be detected on imaging of the fetus. It is one of the triad of features characteristic of Gomez-Lopez-Hernandez syndrome (GLHS). When detected, signs of GLHS ought to be looked for on post-natal review. Signs include partial alopecia and some facial peculiarities.
The initial procedures of choice are goniotomy or trabeculotomy if the cornea is clear, and trabeculectomy ab externo if the cornea is hazy. The success rates are similar for both procedures in patients with clear corneas. Trabeculectomy and shunt procedures should be reserved for those cases in which goniotomy or trabeculotomy has failed. Cyclophotocoagulation is necessary in some intractable cases but should be avoided whenever possible because of its potential adverse
effects on the lens and the retina. Epidemiology
In the United States, the incidence of primary congenital glaucoma is about one in 10,000 live births. Worldwide, the incidence ranges from a low of 1:22,000 in Northern Ireland to a high of 1:2,500 in Saudi Arabia and 1:1,250 in Romania. In about two-thirds of cases, it is bilateral. The distribution between males and females varies with geography. In North America and Europe, it is more common in boys, whereas in Japan it is more common in girls. Congenital glaucomaIncidence: one in every 10000-15000 live births. Bilateral in up to 80% of cases. Most cases are sporadic (90%). However, in the remaining 10% there appears to be a strong familial component. See also
Axenfeld syndrome
Peters-plus syndrome
Weill–Marchesani syndrome

References
Further reading
Lively GD, Alward, WL, Fingert JH. Juvenile open-angle glaucoma: 22-year-old Caucasian female referred in 1990 for evaluation of elevated intraocular pressure (IOP). EyeRounds.org. September 17, 2008. External links
231300
137750; MYOC
137750; CYP1B1
Juvenile Glaucoma at eMedicine on eMedicine
Glaucoma for Children on AAPOS. Congenital Primary Glaucoma on patient.info
GeneReview/NCBI/NIH/UW entry on Primary Congenital Glaucoma
Glaucoma entry on PGCFA