Spinocerebellar ataxia type 6 (SCA6) is characterized by adult-onset, slowly progressive cerebellar ataxia, dysarthria, and nystagmus. The age of onset ranges from 19 to 73 years; mean age of onset is between 43 and 52 years. Initial symptoms are gait unsteadiness, stumbling, and imbalance (in ~90%) and dysarthria (in ~10%). Eventually all persons have gait ataxia, upper-limb incoordination, intention tremor, and dysarthria. Dysphagia and choking are common. Visual disturbances may result from diplopia, difficulty fixating on moving objects, horizontal gaze-evoked nystagmus, and vertical nystagmus. Hyperreflexia and extensor plantar responses occur in up to 40%-50%. Basal ganglia signs, including dystonia and blepharospasm, occur in up to 25%. Mentation is generally preserved.

Migraine is a common complex disorder that shows strong familial aggregation. The disorder is generally characterized by chronic episodic headache usually associated with nausea and vomiting (summary by Nyholt et al., 1998). For a phenotypic description and discussion of genetic heterogeneity of migraine headaches, see MGR1 (157300).

Migraine is a complex and heterogeneous disorder characterized by recurrent attacks of headache associated with autonomic and neurologic symptoms. Two primary types of migraine can be distinguished: migraine without aura and migraine with aura. Usually, 1 type of migraine prevails intraindividually. Migraine without aura (MO) is the more common form and is characterized by unilateral pulsating headache of moderate to severe intensity, lasting 4 to 72 hours. The attacks are associated with nausea, vomiting, and photo- and phonophobia and are aggravated by physical activity. Frequency, severity, and duration vary substantially (summary by Soragna et al., 2003). For a phenotypic description and discussion of genetic heterogeneity of migraine headaches, see MGR1 (157300).

Advanced sleep phase syndrome is characterized by very early sleep onset and offset (summary by Jones et al., 1999). For a discussion of genetic heterogeneity of advanced sleep phase syndrome, see FASPS1 (604348).

Migraine is the most common type of chronic, episodic headache, as summarized by Featherstone (1985). One locus for migraine with or without aura (MGR1) has been identified on chromosome 4q24. Other loci for migraine have been identified on 6p21.1-p12.2 (MGR3; 607498), 14q21.2-q22.3 (MGR4; 607501), 19p13 (MGR5; 607508), 1q31 (MGR6; 607516), 15q11-q13 (MGR7; 609179), 5q21 (with or without aura, MGR8, 609570; with aura, MGR9, 609670), 17p13 (MGR10; 610208), 18q12 (MGR11; 610209), 10q22-q23 (MGR12; 611706), and the X chromosome (MGR2; 300125). Mutation in the KCNK18 gene (613655) on chromosome 10q25 causes migraine with aura (MGR13; 613656). See also familial hemiplegic migraine-1 (FHM1; 141500), a subtype of autosomal dominant migraine with aura (MA).

Any migraine disorder in which the cause of the disease is a mutation in the KCNK18 gene.