title: Molecular outcomes, clinical consequences, and genetic diagnosis of Oculocutaneous Albinism in Pakistani population.
abstract: Nonsyndromic oculocutaneous Albinism (nsOCA) is clinically characterized by the loss of pigmentation in the skin, hair, and iris. OCA is amongst the most common causes of vision impairment in children. To date, pathogenic variants in six genes have been identified in individuals with nsOCA. Here, we determined the identities, frequencies, and clinical consequences of OCA alleles in 94 previously unreported Pakistani families. Combination of Sanger and Exome sequencing revealed 38 alleles, including 22 novel variants, segregating with nsOCA phenotype in 80 families. Variants of TYR and OCA2 genes were the most common cause of nsOCA, occurring in 43 and 30 families, respectively. Twenty-two novel variants include nine missense, four splice site, two non-sense, one insertion and six gross deletions. In vitro studies revealed retention of OCA proteins harboring novel missense alleles in the endoplasmic reticulum (ER) of transfected cells. Exon-trapping assays with constructs containing splice site alleles revealed errors in splicing. As eight alleles account for approximately 56% (95% CI: 46.52-65.24%) of nsOCA cases, primarily enrolled from Punjab province of Pakistan, hierarchical strategies for variant detection would be feasible and cost-efficient genetic tests for OCA in families with similar origin. Thus, we developed Tetra-primer ARMS assays for rapid, reliable, reproducible and economical screening of most of these common alleles.
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD, USA.
authors.forename: Mohsin
authors.initials: M
authors.lastname: Shahzad
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD, USA.|Institute of Molecular Biology &Biotechnology, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Sairah
authors.initials: S
authors.lastname: Yousaf
authors.affiliation: Molecular Biology &Genetics Department, Medical Research Center, Liaquat University of Medical &Health Sciences, Jamshoro, Pakistan.
authors.forename: Yar M
authors.initials: YM
authors.lastname: Waryah
authors.affiliation: Gomal Centre of Biochemistry and Biotechnology, Gomal University, D.I. Khan, Pakistan.
authors.forename: Hadia
authors.initials: H
authors.lastname: Gul
authors.affiliation: Institute of Molecular Biology &Biotechnology, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Tasleem
authors.initials: T
authors.lastname: Kausar
authors.affiliation: Institute of Molecular Biology &Biotechnology, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Nabeela
authors.initials: N
authors.lastname: Tariq
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD, USA.
authors.forename: Umair
authors.initials: U
authors.lastname: Mahmood
authors.affiliation: Government College University, Faisalabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ali
authors.affiliation: Gomal Centre of Biochemistry and Biotechnology, Gomal University, D.I. Khan, Pakistan.
authors.forename: Muzammil A
authors.initials: MA
authors.lastname: Khan
authors.affiliation: Molecular Biology &Genetics Department, Medical Research Center, Liaquat University of Medical &Health Sciences, Jamshoro, Pakistan.
authors.forename: Ali M
authors.initials: AM
authors.lastname: Waryah
authors.affiliation: Institute of Molecular Biology &Biotechnology, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Rehan S
authors.initials: RS
authors.lastname: Shaikh
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD, USA.
authors.forename: Saima
authors.initials: S
authors.lastname: Riazuddin
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD, USA.
authors.forename: Zubair M
authors.initials: ZM
authors.lastname: Ahmed
mesh_terms: D016115:Albinism, Oculocutaneous / Q000453:epidemiology* / Q000235:genetics* / Q000473:pathology; D000483:Alleles; D005260:Female; D005787:Gene Frequency; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D020125:Mutation, Missense; D010154:Pakistan / Q000453:epidemiology
chemical_list: D026901:Membrane Transport Proteins; C489600:OCA2 protein, human