(A) MRI of the brain (sagittal section) showing vermal hypoplasia predominantly on the upper levels; (B) Cerebral MRI (axial section) in T1 and T2 showing the enlargement of the upper cerebellar peduncles with the characteristic "molar tooth" appearance. The disorder is characterized by absence or underdevelopment of the cerebellar vermis and a malformed brain stem (molar tooth sign), both of which can be visualized on a transverse view of head MRI scan. Together with this sign, the diagnosis is based on the physical symptoms and genetic testing for mutations. If the gene mutations have been identified in a family member, prenatal or carrier diagnosis can be pursued.<unk>  is known to affect 1 in 80,000-100,000 newborns. Due to the variety of genes this disorder is affected by, it is likely to be under-diagnosed. It is commonly found in Ashkenazi Jewish, French-Canadians, and Hutterite ethnic populations. Most cases of<unk>  are autosomal recessive - in these cases, both parents are either carriers or affected. Rarely,<unk>  is inherited in an X-linked recessive pattern. In these cases, males are more commonly affected because affected males must have one X chromosome mutated, while affected females must have mutated genes on both X chromosomes.
Joubert syndrome
Goldenhar syndrome
Kaufman oculocerebrofacial syndrome
Wolfram syndrome
Hurler–Scheie syndrome
TORCH syndrome
Timothy syndrome
Axenfeld–Rieger syndrome