Troyer Syndrome

Excerpt

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 a proband with characteristic clinical findings and/or biallelic pathogenic variants in SPART identified by molecular genetic testing.

Management: Treatment of manifestations: Feeding therapy and nutritional support; developmental and educational support; antispasticity drugs; daily physical therapy; occupational therapy, assistive walking devices, and ankle-foot orthoses as needed; speech-language therapy to improve or maintain speech and swallowing; communication devices as needed; medication to reduce drooling as needed; antidepressant or mood stabilizer medication for individuals with emotional lability; treatment of skeletal manifestations per orthopedist; development of care plan for transition to adulthood; family and social work support.

Surveillance: At each visit assess growth, feeding, nutrition, developmental progress, educational needs, and family needs; cognitive testing as indicated; neurologic evaluation every six to 12 months or as needed; psychiatric/psychological assessment as indicated; annual assessment of orthopedic manifestations.

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. If both parents are known to be heterozygous for a SPART pathogenic variant, each sib of an affected individual has at conception 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. Once the SPART pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives and prenatal/preimplantation genetic testing for Troyer syndrome are possible.