Troyer Syndrome

Clinical characteristics: Troyer syndrome is characterized by progressive spastic paraparesis, dysarthria, pseudobulbar palsy, distal amyotrophy, short stature, and subtle skeletal abnormalities. Most affected children exhibit delays in walking and speech and difficulty in managing oral secretions, followed by increased lower-limb spasticity and slow deterioration in both gait and speech. Mild cerebellar signs are common. The most severely affected individuals have choreoathetosis. Emotional lability / difficulty in controlling emotions and affective disorders, such as inappropriate euphoria and/or crying, are frequently described. Life expectancy is normal.

Diagnosis/testing: The diagnosis of Troyer syndrome is established in an individual with characteristic clinical findings. Identification of biallelic pathogenic variants in SPART confirms the diagnosis if clinical features are inconclusive.

Management: Treatment of manifestations: Antispasticity drugs; daily physical therapy; occupational therapy, assistive walking devices, and ankle-foot orthotics as needed; antidepressant or mood stabilizer medication for individuals with emotional lability.

Surveillance: Neurologic and developmental/cognitive assessments; monitoring for dysphagia to reduce the risk of aspiration.

Agents/circumstances to avoid: Dantrolene should be avoided in persons who are ambulatory as it may induce irreversible weakness, which can adversely interfere with overall mobility.

Genetic counseling: Troyer syndrome is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk relatives and prenatal testing for pregnancies at increased risk are possible if both pathogenic variants have been identified in an affected family member.