Albinism, or the NOACH syndrome

Abstract

After a 4‐year multidisciplinary study of albinism our findings will be presented here. Over a hundred albinos were examined, together with their heterozygote family members. Given this substantial patient and subject sample we were provided with the opportunity to: evaluate the results of standard diagnostic procedures, for example pedigree analysis, ocular and clinical examination; determine the diagnostic value of biochemical, and ultrastructural tests; and develop a new and viable albino diagnostic protocol, particularly for electrophysiological examination. In the conclusions the following subjects are in order: Diagnosis: Our most important finding up till now is that normally pigmented people who do not look like albinos can in fact be albinos. Differential diagnosis: It appears that patients with autosomal recessive albinism can be normally pigmented, and patients with X‐linked albinism can be severely hypopigmented. We therefore propose to abandon the terms oculo‐cutaneous albinism (OCA), and X‐linked ocular albinism (XOA), and use the terms autosomal recessive albinism, and X‐linked albinism instead. X‐linked albinism Forsius‐Eriksson type (XOAF): We assume that XOAF does not represent a true form of albinism. Classification: Our results indicate that the phenotypical albino classification, which was a base for Witkop et al. (1978) to also obtain a genetical classification, supported by the hairbulb test, has not proved to be useful for the classification of tyrosinase negative (TNOCA), tyrosinase positive oculocutaneous albinism (TPOCA), and autosomal recessive ocular albinism (AROA) as genetically distinct forms. Prevalence: Our prevalence estimate for all forms of albinism is at least 1:15,000, about 10% of the albinos have X‐linked albinism. Definition: We want to modify the albino definition as a hereditary and congenital inborn error of metabolism related to the pigment cell, and resulting in a systemic disorder that is characterized by anomalies of eyes, and hypopigmentation in most cases or absence of pigment in skin, hair, and eyes, and of which the neuro‐anatomical consequences are the most characteristic.

Evidence for Protein–Protein Interaction between Dopamine Receptors and the G Protein-Coupled Receptor 143

“…In pigment cells, it is localized intracellularly at endolysosomes and melanosomes (specialized organelles in which the pigment melanin is synthesized) rather than the cell membrane where most other GPCRs function [ 30 , 31 , 32 ]. GPR143 mutations result in ocular albinism type 1 (OA1) [ 33 ], an X-linked recessive disorder that is characterized by visual anomalies including loss of stereoscopic vision due to misrouting of the optic fibers at the optic chiasm [ 34 , 35 ].…”

Determining a Worldwide Prevalence of Oculocutaneous Albinism: A Systematic Review

“…The findings also show that the reported prevalence rates of OCA vary widely in different populations, for example, 1 in 14,000 in Denmark, 15 versus 1 in 1755 in Namibia, 21 and even in the same population over time, for example, over 31 years in the Netherlands. 16 , 37 …”

“…Two studies from the Netherlands, undertaken 31 years apart, support this finding. 16 , 37 Similarly, Grønskov et al 15 , 53 suggest that there has been an increased prevalence of albinism (their samples include both OCA and some OA cases) in Denmark over time. It is suggested that changes in prevalence rates are actually due to better and more stringent diagnostic criteria, improved case finding and medical care, and (most likely) better methods of selecting cases (Kruijt, personal communication, 2022), determining prevalence and data collection.…”

Primer reporte de albinismo en Dasyprocta fuliginosa (Rodentia: Dasyproctidae)

“…El albinismo es una condición atípica de origen genético caracterizada por la ausencia total de melanina en la piel, ojos y pelos de muchos ver-tebrados (Dorp, 1987;Grouw, 2012;Lamoreux et al, 2010). Esta condición es rara de observar en poblaciones silvestres (Parsons y Bon-drup-Nielsen, 1995), posiblemente por la baja esperanza de vida que tienen los individuos albinos al ser seleccionados negativamente debido a una mayor probabilidad de ser depredados (Sazima y Di-Bernardo, 1991) o por conflictos intraespecíficos (Holt et al, 1995).…”