Genetics of Inherited Retinal Diseases in Understudied Ethnic Groups in Italian Hospitals

Paolo Enrico Maltese; Leonardo Colombo; Salvatore Martella; Luca Rossetti; Said El Shamieh; Lorenzo Sinibaldi; Chiara Passarelli; Andrea Maria Coppè; Luca Buzzonetti; Benedetto Falsini; Pietro Chiurazzi; Giorgio Placidi; Benedetta Tanzi; Matteo Bertelli; Giancarlo Iarossi

doi:10.3389/fgene.2022.914345

Genetics of Inherited Retinal Diseases in Understudied Ethnic Groups in Italian Hospitals

Front Genet. 2022 Jun 28:13:914345. doi: 10.3389/fgene.2022.914345. eCollection 2022.

Authors

Paolo Enrico Maltese¹, Leonardo Colombo², Salvatore Martella², Luca Rossetti², Said El Shamieh³, Lorenzo Sinibaldi^{4

5}, Chiara Passarelli⁴, Andrea Maria Coppè⁶, Luca Buzzonetti⁶, Benedetto Falsini^{6

7}, Pietro Chiurazzi⁸, Giorgio Placidi⁷, Benedetta Tanzi¹, Matteo Bertelli^{1

9}, Giancarlo Iarossi⁶

Affiliations

¹ Magi's Lab S.R.L., Rovereto, Italy.
² Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, Milan, Italy.
³ Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon.
⁴ Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
⁵ Rare Disease and Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
⁶ Department of Ophthalmology, Bambino Gesù Children's Hospital, Rome, Italy.
⁷ Fondazione Policlinico Universitario "A. Gemelli" IRCCS/Universita' Cattolica del S. Cuore, Ophthalmology Unit, Rome, Italy.
⁸ UOC Genetica Medica, Fondazione Policlinico Universitario "A. Gemelli" IRCCS & Istituto di Medicina Genomica, Universita' Cattolica del S. Cuore, Rome, Italy.
⁹ MAGI Euregio s.c.s., Bolzano, Italy.

Abstract

Purpose: Describing the clinical and genetic features of an ethnically heterogeneous group of (inherited retinal diseases) IRD patients from different underrepresented countries, referring to specialized Italian Hospitals, and expanding the epidemiological spectrum of the IRD in understudied populations. Methods: The patients' phenotypes underwent were characterized by exhaustive ophthalmological examinations, including morpho-functional testing. Genetic testing was performed using next-generation sequencing (NGS) and gene sequencing panels targeting a specific set of genes, Sanger sequencing and-when necessary-multiplex ligation-dependent probe amplification (MLPA) to better identify the genotype. When possible, segregation analysis was performed in order to confirm unsolved cases. Results: The article reports the results of the phenotypes and genotypes of 123 IRD probands, 69 males and 54 females, mean age 41 (IQR, 54-30) years, disease onset at 13 (IQR, 27.25-5) years. Thirty-three patients out of 123 (26.8%) were Africans (North/Northwest Africa), 21 (17.1%) Asians, 19 (15.4%) Americans (South/Central America) and 50 (40.7%) Europeans (Eastern Europe). Retinitis pigmentosa was the most represented phenotype (56%), followed by cone dystrophy (11%) and Leber congenital amaurosis (7%), while ABCA4 was the most frequently mutated gene (18%), followed by USH2A (9%) and RPGR (5%). About ABCA4 variants found in Stargardt disease, macular and cone dystrophies were predominant in Asian (42%) and European (21%) patients. The most represented inheritance pattern was autosomal recessive, while a higher frequency of homozygous patients versus compound heterozygotes as compared to previous studies on Italian IRD patients was evidenced, reflecting a possible higher frequency of inbreeding marriages. Conclusion: Though limited by the relatively low number of patients, the present paper paints a picture of the clinical and genetic features of IRD patients from understudied ethnic groups referred to Italian specialized hospitals and extended the epidemiological studies on underrepresented world regional areas.

Keywords: genetic epidemiology; inherited retinal diseases; next generation sequencing; sanger sequencing; understudied ethnic groups.