A 20-year-old woman presented with mental retardation and a history of stroke 
related to moyamoya disease at the age of 8 years. She had cognitive impairment 
which became more pronounced after the stroke. This patient's parents were first 
cousins and six close family relatives had strokes in their 60s or 70s. The 
patient's 16-year-old sister had learning disability, chronic muscle pain, and 
an ECG suggestive of previous hypoxemic heart injury. The two sisters had 
similar dysmorphic facial appearance including a prominent philtrum, bulbous 
nose, and severe acne. They both had increased subcutaneous tissue in their 
faces, whereas their bodies were slim. Both sisters were found to have elevated 
levels of rheumatoid factor, C-reactive protein, and erythrocyte sedimentation 
rate on repeat measurements. Partial autoimmunity screening in one of the 
patients was negative. Chromosome analysis and array comparative genomic 
hybridization analyses were also normal. Nerve conduction findings in the 
younger sister were consistent with distal, predominantly motor, demyelinating 
neuropathy localized to the lower extremities. We propose that these two sisters 
suffer from a new autosomal recessive syndrome. Carrier status for this 
condition may predispose to later onset stroke.