Objective:

To report a family with coexistence of 2 rare, unrelated neurologic disorders.

Background:

Advances in genetic diagnosis have provided insights into phenotypic and genotypic heterogeneity of many disorders with proper identification of atypical clinical pictures. We present a family with two distinct genetically proven neurologic disorders, with both disorders occurring in one member.

Design/Methods:

Case-report of family members seen in neuromuscular clinic who underwent genetic testing.

Results:

Three family members were evaluated for progressive neurologic symptoms. A 59-year-old woman presented with gait difficulty, spasticity, and brisk reflexes. After ruling out acquired causes of myelopathy, genetic testing confirmed a spastin mutation consistent with autosomal dominant hereditary spastic paraplegia (SPG4). Her 63-year-old sister, followed in the same clinic, was previously diagnosed with genetically confirmed myotonic dystrophy type 1 (DM1) at age 49 after developing progressive weakness and impaired fine motor control. On neurologic exam, she also had brisk reflexes and ankle clonus. A workup for acquired etiologies of the brisk reflexes was unrevealing. After SPG4 was diagnosed in her sister, she underwent focused genetic testing which confirmed a concurrent spastin mutation. Their 58-year-old brother is followed for gait difficulty and bulbar weakness with a genetically confirmed diagnosis of DM1. He does not exhibit signs of HSP such as brisk reflexes or spasticity, so further testing was not performed. Clinical details and investigations will be presented.

Conclusions:

The presence of atypical findings in patients and family members with known genetic disorders should prompt evaluation for concurrent genetic disorders after excluding acquired etiologies. Knowledge of phenotypes of rare disorders and a careful clinical examination therefore remain essential, especially as novel treatments for genetic disorders are developed.