1. ¹Department of Pediatrics, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
2. ²Department of Biochemistry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
3. ³Department of Ophthalmology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
4. ⁴Human Medical Genetics Program, University of Colorado Health Sciences Center-Fitzsimons, Aurora, Colarado, USA

Correspondence: Dr Carmen L. Cadilla, Department of Biochemistry, University of Puerto Rico School of Medicine, PO Box 365067, San Juan PR 00936-5067, Puerto Rico. E-mail: ccadilla@rcm.upr.edu

Received 21 June 2005; Revised 11 September 2005; Accepted 27 September 2005.

Abstract

Hermansky–Pudlak syndrome (HPS) (MIM #203300) is a heterogeneous group of autosomal recessive disorders characterized by oculocutaneous albinism (OCA), bleeding tendency, and lysosomal dysfunction. HPS is very common in Puerto Rico (PR), particularly in the northwest part of the island, with a frequency of 1:1,800. Two HPS genes and mutations have been identified in PR, a 16-base pair (bp) duplication in HPS1 and a 3,904-bp deletion in HPS3. In Puerto Ricans with more typical OCA, the most common mutation of the tyrosinase (TYR) (human tyrosinase (OCA1) gene) gene was G47D. We describe screening 229 Puerto Rican OCA patients for these mutations, and for mutations in the OCA2 gene. We found the HPS1 mutation in 42.8% of cases, the HPS3 deletion in 17%, the TYR G47D mutation in 3.0%, and a 2.4-kb deletion of the OCA2 gene in 1.3%. Among Puerto Rican newborns, the frequency of the HPS1 mutation is highest in northwest PR (1:21; 4.8%) and lower in central PR (1:64; 1.6%). The HPS3 gene deletion is most frequent in central PR (1:32; 3.1%). Our findings provide insights into the genetics of albinism and HPS in PR, and provide the basis for genetic screening for these disorders in this minority population.