To report the second patient with an autosomal recessive spinocerebellar ataxia 16 (SCAR16) associated with cervical dystonia, expand the phenotype of this rare condition and present the comprehensive phenotypic summary of all known carriers to date.

A combination of dysarthria, ataxia and dystonia in one patient has a wide differential. Obtaining a diagnosis is often a challenging, laborious, but rewarding process.

Subacute-onset cerebellar ataxia affecting siblings and skipping generations is suggestive of an autosomal-recessive hereditary ataxia, including Fredreich’s ataxia, ataxia teleangiectasia, ataxia with oculomotor apraxia and SCAR. 

SCAR 16 is a rare condition described in a handful of families worldwide. It is caused by a homozygous/compound heterozygous mutation in STUB1gene.

We describe a 45-year-old right-handed woman with a 6-month history of progressive speech and balance problems. Main features on examination were cervical dystonia, ataxia and dysarthria. Her 47-year old estranged sister had dysarthria and cognitive problems (declined the assessment).

MRI brain (proband) showed severe cerebellar atrophy. Multiple laboratory and genetic tests were negative.Exome sequencing results were suggestive of SCAR16.

Two compound heterozygous variants in STUB1gene were detected (1 novel). TOPOcloning showed variants to be in "trans" suggesting the pathogenicity.

To date SCAR16 was described only in 11 families worldwide.The phenotype usually consists of:cognitive impairment, cerebellar and pyramidal signs and hormonal problems. Our patient is the second patient with dystonia reported to date. Moreover the families reported are of Asian origin, with three families from Saudi Arabia, Germany and Turkey.Our patient is the only other individual with European descent. 

We expand SCAR16 genotype and phenotype (the second report of dystonia, novel variant) and provide a comprehensive overview of all described cases to date.