To analyze the genotypes and clinical phenotypes of two families with Hermansky-Pudlak syndrome (HPS).

The method of pedigree investigation was adopted.A Han Chinese HPS family and a Hui Chinese HPS family were enrolled in People's Hospital of Ningxia Hui Autonomous Region from June 2020 to May 2021.Clinical data of two probands and their phenotypically normal parents were collected.Relevant ocular and systemic examinations were carried out.Platelet dense granules in the two probands were observed with an electron microscope.DNA was extracted from peripheral venous blood collected from the subjects.The pathogenic genes were screened by whole exome sequencing.The potential disease-causing variations were analyzed by bioinformatics analysis.Validation and family cosegregation analysis of the pathogenic variations were performed by Sanger sequencing.The relationship between HPS-related gene variations and clinical characteristics was explored.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region (No.2016018).Written informed consent was obtained from each subject or custodian before any medical examination.

The two families were consistent with autosomal recessive inheritance pattern.In family 1 with a family history of consanguineous marriage, the proband had no obvious hypopigmentation on his facial skin, hair, eyebrows and eyelashes.Horizontal nystagmus, exotropia, mild visual impairment, iris atrophy, positive light transmission, orange fundus, pigment loss, macular hypoplasia, prolonged prothrombin time in laboratory examination, and a significant reduction of platelet dense granules by electron microscopy were observed.The proband in family 2 had pale brown hair and eyebrows, severe visual impairment, normal iris pigment, longer thrombin time in laboratory tests, and characteristics similar to those of the proband in family 1.A novel homozygous variant c. 2887G>T (p.E963X) was detected in the HPS3 gene of the proband in family 1.The parents of the proband from family 1 both carried a heterozygous variant c.2887G>T (p.E963X).Compound heterozygous variants were detected in HPS5 gene of the proband in family 2, c.2952-2A>C splicing variation and heterozygous deletion (a 3 144-bp deletion, located in chr11: 18302108-18305251, exon 22).The parents of the proband from family 2 carried a heterozygous variation.The three novel variations were labeled as pathogenic according to the ACMG standards and guidelines.

Family 1 is with HPS-3 and family 2 is with HPS-5.There is a certain genotype-phenotype correspondence in the two types of HPS.

Hermansky-Pudlak syndrome; Pedigree; Genetic testing; Whole exome sequencing; Genotype; Phenotype; HPS3 gene; HPS5 gene