A 38-year old female presented for evaluation of progressive hypophonia since age 29. On neurological exam, she had masked facies, bradykinesia, asymmetric upper extremity rigidity, micrographia, and tremor of hands and chin consistent with parkinsonism. Trials of levodopa/carbidopa and pramipexole improved tremors. MRI was normal. Her past history was notable for height in the 15^th percentile, retinal dystrophy, and cataracts.  Additional findings include joint hypermobility, scoliosis, micrognathia, high arched palate, sensorineural hearing loss, and pectus excavatum.  Family history was unrevealing with no consanguinity.  A chromosomal microarray uncovered complete UPD of chromosome 1.  Whole exome sequencing identified homozygous pathogenic variants in PARK7 (c.331delG, p.A111LfsX7), ABCA4 (c.1805g>a, p.R406Q), and COL9A2 (c.1982c>t, p.P661L).  Her asymptomatic father was heterozygous for all three variants.

Complete isodisomy of chromosome 1 resulting in homozygous PARK7, ABCA4, and COL9A2 changes explain the complex phenotype in this patient including early-onset PD, Stargardt’s macular dystrophy (retinal dystrophy), and Stickler syndrome (cataracts, dysmorphisms, short stature), respectively.

Previous reports of PD due to PARK7 are primarily in consanguineous families. Exploring unusual mechanism of inheritance such as UPD should be considered when encountering rare recessive homozygous mutations in the absence of consanguinity, complex and seemingly unrelated phenotypes, or multiple rare genetic diagnoses.