Albino Research Articles

HERMANSKY-PUDLAK SYNDROME-ASSOCIATED INFLAMMATORY BOWEL DISEASE: A SYSTEMATIC REVIEW ON CLINICAL MANIFESTATIONS AND INVESTIGATIONS INTO OPTIMAL MANAGEMENT

Abstract Hermansky-Pudlak Syndrome (HPS) is a rare autosomal condition resulting from a mutation in 1 of at least 7 different genes leading to the triad of tyrosine-positive oculocutaneous albinism, platelet dysfunction leading to prolonged bleeding time, and ceroid lipofuscin within the reticuloendothelial system. The latter of these can result in systemic derangements including renal failure, pulmonary fibrosis, cardiomyopathy, and a disabling granulomatous colitis. This colitis is a unique type of inflammatory bowel disease (IBD) with complications such as intestinal fistulization, ileitis, enterocolitis and perianal disease. There is data to suggest that HPS colitis is due to the development of classical IBD. However, optimal management remains undetermined. Our systematic review aims to analyze the clinical presentation behind HPS colitis, endoscopic versus histopathological findings, and ultimate treatment plans required for optimal management of this disease among HPS genotypes. A comprehensive literature review was conducted on patients with HPS and its associated colitis manifestations from inception to August 2023. Analyses on patient demographics, clinical presentation, HPS genotype, endoscopic versus histopathological findings, medical versus surgical interventions were thoroughly performed. Six cohort studies on HPS patients with coexisting colitis were identified. A total of 84 patients comprised these studies with mean age 32 +/- 9.65. Racial breakdowns were 68% Puerto Rican, 23% white, 4% Indian, 2% Mexican, 1% Honduran, and 1% African American. 59 patients had the HPS-1 genotype, 8 with HPS-3, 3 with HPS-4, and 1 with HPS-6. The most common presenting symptoms were hematochezia (37%), diarrhea (23%), abdominal pain (16%), and constipation (10%). Endoscopic evaluation showed normal gross findings in 65% of cases and abnormalities in only 35%. However, IBD-associated histopathological positivity was more prevalent with the most common findings being granulomas (33%), macrophages without colitis (19%), macrophages with colitis (15%), and lymphoid aggregates (10%). Medical therapy was initiated in 48 cases with the most common medications being steroids (46%), followed by anti-TNFa agents (40%), and immunomodulators (35%). 28 cases required surgical intervention with the most common operation performed being a (subtotal) colectomy and ileostomy. There were scattered cases of laparoscopic loop ileostomies, total colectomies, and proctocolectomies too. Interestingly, 10 patients received no intervention whatsoever. HPS-associated colitis is a debilitating condition that remarkably resembles IBD. There is no consensus on optimal therapy and many patients ultimately require operative intervention. The HPS-1 gene appears to be highly prevalent in this condition and younger patients are more affected, however more research is needed.

Generation and characterization of retinal pigment epithelium from patient iPSC line to model oculocutaneous albinism (OCA)1A disease

Generation and characterization of retinal pigment epithelium from patient iPSC line to model oculocutaneous albinism (OCA)1A disease

Case series: Fundus autofluorescence abnormalities in a family of ocular albinism carriers.

Carriers of ocular albinism demonstrate signs of retinal mosaicism with unique features on fundus autofluorescence testing, which differentiate this condition from other x-linked retinal disorders in carrier patients. Distinctive findings include a mud-splattered fundus with peripheral hyperpigmented streaks, which correlate with areas of hyperautofluorescence and hypoautofluorescence. This is the first reported case series of a family that demonstrates diagnostic retinal and fundus autofluorescence abnormalities related to retinal mosaicism in three sisters who were unaware they were carriers of ocular albinism type 1. Multimodal imaging, electrodiagnostic testing, and genetic testing can be used to confirm the diagnosis and differentiate this clinical presentation from other sight-threatening hereditary retinal diseases. Three sisters, aged 21, 17, and 13 years, were referred to determine the cause of abnormal retinal pigmentation. All presented with normal vision, and anterior segment examination was unremarkable without iris transillumination. They denied family history of ocular disease. Fundus examination of all three sisters revealed a mud-splattered pattern of pigmentation in the posterior pole and radial pigmentary streaks. Fundus autofluorescence showed a pattern of hyperautofluorescence and hypoautofluorescence corresponding to this pigmentary pattern. Spectral domain optical coherence tomography, electro-oculogram, and electroretinogram were normal in all three sisters. Genetic testing of their father, who was unaware of any disorder, tested positive for ocular albinism. Ocular albinism carriers have abnormal retinal pigmentation in a characteristic pattern. Fundus autofluorescence shows a correlative pattern that can confirm carrier status of ocular albinism in individuals unaware of their status and rule out other retinal degenerations.

First record of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups on Marion Island

We report on an occurrence of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups born on Marion Island, Prince Edward Archipelago. While previous observations have documented pups with atypical lanugo pelage colorations, this is the first case involving hypopigmentation of both fur and other tissues, including the eyes and nails. During the austral summer of 2021/22, we encountered four sub-Antarctic fur seal pups displaying this anomalous pigmentation. These anomalous individuals were found along two beaches on the island’s western side and one beach on the eastern side during an island-wide fur seal census. Although the characteristics observed strongly suggest ocular albinism, confirmation would be necessary through genetic analyses. The absence of melanin in mammalian eyes is known to compromise visual acuity, which may likely result in reduced survival beyond the weaning period, explaining the paucity of such adults in this well-observed population.

Анализ эффективности нового способа выявления ахроматопсии

Aim: to assess the efficacy of a novel method for diagnosing achromatopsia. Patients and Methods: twenty patients with congenital achromatopsia established by genetic testing were enrolled. Sixteen (80%) patients were diagnosed with mutations in the CNGB3 gene and 4 (20%) patients were diagnosed with mutations in the CNGA3 gene. The control group 1 (with eye diseases) included 37 patients with congenital optic atrophy and 5 patients with oculocutaneous albinism. The control group 2 (without eye diseases) included 40 individuals. At the initial stage of the study, we compared the perception of brightness of chromatic and achromatic images in patients with achromatopsia. To this end, we employed our own images with specific characteristics of color tone, lightness (brightness), and saturation. The results of the first phase have demonstrated that for most patients with achromatop-sia, the lightest and least distinguishable images on a white background are blue. In light of this, we developed tests to detect achromatopsia (tests #1 and #2). Each test comprises four gray silhouette images (with a lightness of 80% for test #1 and 50% for test #2) and four blue images (R0/ G255/B255). For the blue images, saturation is maximal (S 100%) in both tests, while luminosity is L 80% for test #1 and L 50% for test #2. Results: all individuals in the control group 2, patients with optic atrophy and oculocutaneous albinism, were able to see all blue and gray images of both tests and easily identified the blue images corresponding to the gray (achromatic) ones. In the first test, 95% of patients with achromatopsia (n=19) were unable to see blue images or distinguish their shape from gray images. In contrast, all patients were able to distinguish the shape of gray images of the same lightness and specify them. In test #2 (L 50%), the majority of patients (n=13, 65%) exhibited difficulties with the shape of blue images. The remaining seven patients (35%) demonstrated the ability to name blue images and match them to gray images. Two of them were diagnosed with mutations in the CNGA3 gene, while five of them were diagnosed with mutations in the CNGB3 gene. Therefore, the cone system disorder in these patients was less severe than in the others. Conclusion: the achromatopsia test, developed on the basis of comparative analysis of perceived luminosity of chromatic and achromatic images, is simple and accessible. This test provides preliminary differential diagnosis with other eye diseases and determines the most appropriate strategy of further examinations to establish the diagnosis. KEYWORDS: achromatopsia, color vision, method to diagnose achromatopsia, color per-ception abnormality, monochromacy, color vision deficiency, color disfunction. FOR CITATION: Sukhanova N.V., Rychkova S.I., Likhvantseva V.G., Sandimirov R.I., Kadyshev V.V., Zinchenko R.A. Analyzing the efficacy of a novel method for detecting achromatopsia. Russian Journal of Clinical Ophthalmology. 2024;24(2):49–54 (in Russ.). DOI: 10.32364/2311- 7729-2024-24-2-1.

Analysis of Lipoprotein Signaling in Iris Melanocytes.

Lipids are compounds involved in many biologic functions including cell structure, metabolism, energy storage and are involved in signaling. A prominent lipid in these functions is cholesterol. Cholesterol also plays a part in the signaling of melanocytes, which contain melanosomes. The maturation of these melanosomes happens during melanocyte growth. The deficit of melanogenesis or melanosome maturation is associated with ocular albinism in the eye. Aberrations of melanosome maturation are also associated with pigment dispersion syndrome. Albinism and pigment dispersion manifestations are systemic. Both melanogenesis and melanocyte maturation are affected by cholesterol metabolism. Cholesterol signaling is a part of many pathways in the body, and evaluating these signals can have implications in systemic disease processes of melanogenesis and melanosome maturation, like ocular albinism and pigment dispersion. Cholesterol is carried by lipoprotein particles. Low-density lipoprotein (LDL) is usually the transport vehicle for cholesterol to reach tissues and organelles. The LDL uptake on cells often sends out a cascade of internal signaling within the cells. We describe here LDL signaling related to lipase activity changes using enzymatic methods with a kit. We describe analyses of cholesterol esters and free cholesterol with liquid chromatography and gas chromatography with or in tandem with mass spectrometry (GC-MS and LC-MS/MS). These analyses will provide insight into melanosome maturation and melanogenesis. The methods described here are applicable to all melanocytes within the body of a model mammalian organism.

Hermansky-Pudlak Syndrome with an Improvement in the Respiratory Symptoms after the Administration of Pirfenidone: A Case Report.

Herein, we report a case of Hermansky-Pudlak syndrome (HPS) in which respiratory symptoms improved with pirfenidone treatment. A 43-year-old Japanese woman with oculocutaneous albinism presented with a cough and dyspnea. High-resolution computed tomography revealed areas of reticular and frosted lung opacities. The diagnosis of HPS was confirmed by a prolonged bleeding time and HPS1 gene mutation. Generally, there is no effective treatment for interstitial pneumonia associated with HPS except for lung transplantation. In the present case, the cough and dyspnea improved with pirfenidone administration. Therefore, clinicians should administer pirfenidone in challenging transplantation cases and during the waiting period for transplantation.

Creation of rice doubled haploids with low amylose content using in vitro anther culture.

In vitro androgenesis is a unique model for producing homozygous doubled haploid plants. The use of haploid biotechnology accelerates to obtain of doubled haploid plants, which is very important in rice breeding. The purpose of this work is to improve the production of doubled haploids in rice anther culture in vitro and selection of doubled haploid plants with valuable traits. The study the influence of nutrient media on the production of calli and plant regeneration processes in anther culture of 35 rice genotypes was revealed a significant influence of nutrient media on callus production. It was shown that the addition to culture medium phytohormones ratio with high level of cytokinin (5.0 mg/L BAP) and a low level of auxin (0.5 mg/L NAA), supplemented with amino acid composition promotes high production of green regenerated plants (68.75%) compared to albino plants (31.25%). As a result, doubled haploid lines of the glutinous variety Violetta were selected, which characterized by a low amylose content variation (from 1.86 to 2.80%). These doubled haploids are superior to the original variety in some yield traits and represent valuable breeding material.

A case for the inclusion of oculocutaneous albinism as a skin-related Neglected Tropical Disease

Oculocutaneous albinism (OCA) is genetically transmitted. In this paper we advocate for this disease to be included in the NTD list of the WHO. OCA type 2 is the most common form of albinism in sub-Saharan Africa, with a prevalence of 1 in 7900 among the Bamileke of Cameroon, 1 in 3900 in South Africa and 1 in 1100 among the Ibos of Nigeria, as compared to a prevalence of 1 in 10,000 among African Americans and 1 in 36,000 among White Americans and Europeans. The medical problems related to ophthalmological aspects (poor visual acuity, ametropia, nystagmus, photophobia) and dermatological aspects of albinism (sensitivity to UV rays from the sun and development of skin cancers) are well known. However, their management is often challenging for persons with albinism in sub-Saharan Africa because of their financial burden and the difficulty of accessing medical specialists. In many African countries, persons with albinism are also very often the subject of social, cultural, medical, moral and economic discrimination, which can limit their access to education, employment and community life. They are considered 'white Africans', intermediary and incomplete, with innate powers for good and evil. This particularity has made persons with albinism the targets of mutilations and/or ritual attacks for the purposes of using their body parts in the preparation of charms to bring good luck, health or prosperity. On 13 June 2013, as a result of lobbying by the Canadian NGO Under the Same Sun and African albinism associations, United Nations bodies including UNESCO and the WHO (World Health Organization) responded and a Resolution addressing the discrimination and attacks was voted in. The date has since become International Albinism Awareness Day and is celebrated on a different theme each year with great energy and impact, especially by French, English and Portuguese speaking albinism associations across sub-Saharan Africa. In 2015 the Human Rights Council created the position of Independent Expert on Albinism to better collect and analyse data on the rights of persons with albinism around the world, and especially in countries where ritual attacks occur. The data collected by albinism associations and the authorities thus go directly to the UN Human Rights Directorate. Despite this international attention to the attacks on persons with albinism, one of the biggest threats is skin cancer, which very often leads to early death. In 2022, the WHO launched a strategic framework for the control and management of neglected skin-related neglected tropical diseases - an additional reason to include oculocutaneous albinism as an NTD. Although the focus is currently limited to dermatoses of an infectious nature, we argue here for the integration of oculocutaneous albinism among NTDs because the deadliness of these carcinomas in sub-Saharan Africa is well-known and has been examined in a number of medical publications. Here, we propose that oculocutaneous albinism in sub-Saharan Africa be classified as an NTD to help people with albinism have access to health, economic, social and cultural rights.

Shining Light on Albinism: A Family Case Series

Albinism is a common hereditary condition characterized by the absence or reduction of melanin production in melanocytes, resulting in the distinctive white appearance of the skin, hair, and eyes. The complex process of melanin production involves the tyrosinase enzyme, copper, tyrosine (phenylalanine), and is under genetic control. Ocular albinism, primarily affecting the eyes, is X-linked and presents with varying amounts of melanin in the hair and skin. However, some individuals exhibit a complete absence of melanin in the skin, eyes, and hair, which is transmitted as an autosomal recessive trait. The incidence of albinism varies across populations, with a higher prevalence observed in regions with darker skin tones, such as Africa, where the incidence is approximately 1 in 200 individuals. In contrast, in regions with predominantly light-colored skin, like Europe, albinism is less prevalent, affecting approximately 1 in 2000 individuals. India, with its diverse population, presents a unique context, making individuals with albinism easily noticeable. Exposure to sunlight can lead to sunburn and photophobia, further limiting their daily activities and livelihoods. In this case series, we present five cases of albinism within a single family, highlighting the challenges they face in their daily lives, including the avoidance of outdoor activities due to sun sensitivity. The psychological schemas of experiencing feelings of shyness, embarrassment, and social withdrawal due to the heightened visibility of their condition were discussed in focused group discussion. This case series underscores the importance of understanding and addressing the unique social and healthcare needs of individuals and families affected by albinism in diverse global contexts. Keywords: Albinism, Melanocyte, Melanin, Tyrosinase, OA (ocular albinism), OCA (Oculocutaneous Albinism)

TYR mutation in a Chinese population with oculocutaneous albinism: Molecular characteristics and ophthalmic manifestations

Oculocutaneous albinism (OCA) is a rare inherited disorder characterized by a partial or complete reduction of melanin biosynthesis that leads to hypopigmentation in the skin, hair and eyes. The OCA1 subtype is caused by mutations in TYR. The purpose of this study was to investigate the genetic and clinical ophthalmic characteristics of TYR mutations in patients with OCA. Herein, 51 probands with a clinical diagnosis of OCA were enrolled. Whole-exome sequencing and comprehensive ophthalmic examinations were performed. Overall, TYR mutations were detected in 37.3% (19/51) in the patients with OCA. Fifteen patients had compound heterozygous variants, and four cases had homozygous variants. Eleven different pathogenic variants in TYR were detected in these 19 patients, with missense, insertion, delins and nonsense in 71.1% (27/38), 15.8% (6/38), 2.6% (1/38), and 10.5% (4/38), respectively. Clinical examinations revealed that 84.2% (16/19) of patients were OCA1A, and 15.8% (3/19) were OCA1B. Most TYR probands (52.6%, 10/19) had moderate vision impairment, 15.8% (3/19) had severe visual impairment, 10.5% (2/19) exhibited blindness, only 5.3% (1/19) had mild visual impairment and 15.8% (3/19) were not available. Photophobia and nystagmus were found in 100% (19/19) of the patients. In addition, grade 4 foveal hypoplasia was detected in 100% (12/12) of the patients. In conclusion: The TYR patients exhibited severe ocular phenotypes: the majority (93.8%, 15/16) of them had a moderate vision impairment or worse, and 100% (12/12) had severe grade 4 foveal hypoplasia. These novel findings could provide insight into the understanding of OCA.

Integrated sun protection advice for the South African population.

Exposure to solar ultraviolet radiation (UVR) is associated with several cutaneous adverse effects. However, to the best of our knowledge, in South Africa there are no formal guidelines on sun protection. A group of South African dermatologists and researchers convened over the course of 1 year to deliberate on integrated advice for sun protection among the multi-ethnic South African population. For people with light skin and those with genetic skin disorders (e.g., oculocutaneous albinism), sun protection was identified as critical to prevent sunburn, skin cancer, and photoaging. The evidence is less clear for people with medium and darker skin types, especially the latter, in whom melanin may confer a degree of protection against some parts of the solar spectrum. Recent studies have demonstrated that visible light can cause pigmentary changes in individuals with darker skin types in particular. Sun protection for people of all skin colors is beneficial to protect against photoaging and ocular damage. Herein sun protection advice is suggested for South Africans of all skin colors to reduce morbidity and mortality from sun exposure, particularly relating to skin cancer. Several knowledge gaps are identified as future research priorities.

Molecular insights into the mechanisms of a leaf color mutant in Anoectochilus roxburghii by gene mapping and transcriptome profiling based on PacBio Sequel II

Plants with partial or complete loss of chlorophylls and other pigments are frequently occurring in nature but not commonly found. In the present study, we characterize a leaf color mutant ‘arly01’ with an albino stripe in the middle of the leaf, which is an uncommon ornamental trait in Anoectochilus roxburghii. The albino “mutant” middle portion and green “normal” leaf parts were observed by transmission electron microscopy (TEM), and their pigment contents were determined. The mutant portion exhibited underdevelopment of plastids and had reduced chlorophyll and other pigment (carotenoid, anthocyanin, and flavonoid) content compared to the normal portion. Meanwhile, comparative transcript analysis and metabolic pathways mapping showed that a total of 599 differentially expressed genes were mapped to 78 KEGG pathways, most of which were down-regulated in the mutant portion. The five most affected metabolic pathways were determined to be oxidative phosphorylation, photosynthesis system, carbon fixation & starch and sucrose metabolism, porphyrin and chlorophyll metabolism, and flavonoid biosynthesis. Our findings suggested that the mutant ‘arly01’ was a partial albinism of A. roxburghii, characterized by the underdevelopment of chloroplasts, low contents of photosynthetic and other color pigments, and a number of down-regulated genes and metabolites. With the emergence of ornamental A. roxburghii in southern China, ‘arly01’ could become a popular cultivar due to its unique aesthetics.

Novel Variants of HPS6 Cause Suspected Ocular Albinism: A Report of 2 Cases and the Profile of HPS6 Variants

Introduction: Hermansky-Pudlak syndrome (HPS) is a rare autosomal-recessive disease characterized by ocular albinism (OA) or oculocutaneous albinism (OCA), platelet dysfunction, and other symptoms. This study aimed to analyze the molecular defect in two Chinese families with suspected OA, as well as to investigate the profile of HPS6 variants and their genotype-phenotype correlations. Methods: Seven members from two families were recruited and underwent clinical ophthalmologic examinations. The genomic DNA was extracted from peripheral blood leukocytes. Whole-exome sequencing was performed on the proband of family JX. The single coding exon of HPS6 was directly Sanger sequenced based on PCR amplification in all available family members. An additional 46 probands from families or sporadic cases with the pathogenic variants of HPS6 reported in the literature were reviewed. Results: We identified two different compound heterozygous truncating variants of HPS6 in probands with suspected OA from two independent families. The proband of family JX had c.1674dup and c.503-504del variants, and the other proband from family CZ had a nonsense variant of c.1114C>T and a frameshift variant of c.1556del. Among them, c.1674dup and c.1556del variants in HPS6 have not been reported previously. Therefore, our patients were diagnosed as HPS6 disease by molecular diagnostics. In the retrospective cohort of HPS6 patients, we delineated the profile of HPS6 variants and revealed a significant overlap between CpG islands and the variants of HPS6, suggesting a potential link between DNA methylation and HPS6 variants. We also observed a spatial aggregation of the variants in 3D structure of HPS6 protein, implying the possible functional significance of these structural regions. In addition, we did not find any significant genotype-phenotype correlation of HPS6, and neither did we observe a correlation between the truncation length of the HPS6 protein and the phenotype of HPS6 disease. Conclusion: Our research expands the spectrum of HPS6 variants, providing a comprehensive delineation of their profile and systematically investigating genotype-phenotype correlations in HPS6. These findings could offer potentially valuable clues for investigating the molecular mechanism underlying HPS6 pathogenesis, as well as aiding the clinical diagnosis of HPS6 patients and improving disease prognosis.

Birth stories of South African mothers of children with albinism: A critical human rights analysis

BackgroundThe genetic condition of oculocutaneous albinism is disproportionately present in Africa. Little research has addressed the experiences of mothers impacted by albinism, even though they are more likely to be impacted by human rights violations. MethodsA qualitative study was designed to examine the resilience of mothers affected by albinism in South Africa. Virtual and in-person fieldwork was conducted with the facilitation of community-based researchers and local cultural liaisons. FindingsGiving birth to a child with albinism in South Africa, as in many parts of sub-Saharan Africa, was a life-defining moment for mothers and their families, setting them on a trajectory of health-related stigma, gender inequalities, reduced access to social determinants of health, and other human rights violations. Mothers engaged in sense-making processes shaped by the responses of birth attendants and families, and that reflected social discourses. Their resilience was impacted by access to health teaching, genetic counselling, and health and social services, which were often incomplete or absent all together. Civil society organizations, peer groups, and faith communities were vital in filling these gaps. ConclusionsThe experience giving birth to a child with albinism was both the same and different compared to mothers forty years earlier. What varied was the digital availability of health information; progressive health and social policies and resourcing; and human rights instruments. These transformations point to best practices to support mothers’ resilience.

An efficient protoplast-based genome editing protocol for Vitis species.

CRISPR-Cas technologies allow for precise modifications in plant genomes and promise to revolutionize agriculture. These technologies depend on the delivery of editing components into plant cells and the regeneration of fully edited plants. In vegetatively propagated plants, such as grape, protoplast culture provides one of the best avenues for producing non-chimeric and transgene-free genome-edited plants. However, poor regeneration of plants from protoplasts has hindered their implementation for genome editing. Here, we report an efficient protocol for regenerating plants from protoplasts from multiple grape varieties. By encapsulating the protoplasts in calcium alginate beads and co-culturing them with feeder cultures, the protoplasts divide to form callus colonies that regenerate into embryos and ultimately plants. This protocol worked successfully in wine and table grape (Vitis vinifera) varieties, as well as grape rootstocks and the grapevine wild relative Vitis arizonica. Moreover, by transfecting protoplasts with CRISPR-plasmid or ribonucleoprotein (RNP) complexes, we regenerated albino plants with edits in VvPHYTOENE DESATURASE gene in three varieties and in V. arizonica. The results reveal the potential of this platform to facilitate genome editing in Vitis species.

Does Foveal Hypoplasia Affect Emmetropization in Patients with Albinism?

(1) Background: The aim of the study was to describe refractive development from early childhood to adulthood in Danish patients with albinism and to evaluate the effect of foveal developmental stage on refractive development; (2) Methods: Patients with a clinical diagnosis of ocular or oculocutaneous albinism were invited for a refractive evaluation and comprehensive phenotyping including macular optical coherence tomography (OCT) scans. Foveal hypoplasia was graded based on OCT from 0 (normal) to 4 (absence of any signs of foveal specialization). Medical files were reviewed for historical refractive values in individual patients; (3) Results: Hyperopia (spherical equivalent refraction (SEQ) of ≥+1 Diopter (D)) was common in both children (81.3%) and adults (67.1%). The lower prevalence of hyperopia in adults was predominantly explained by increasing astigmatism with age. Emmetropization (>2D change from before 3 years to adolescence) was seen in 22.2%. There was no influence on foveal hypoplasia grade on the degree of refractive errors throughout life; (4) Conclusions: We found that emmetropization was uncommon in Danish patients with albinism and that the degree of foveal developmental stage did not influence emmetropization or the distribution of refractive errors. High degrees of hyperopia and astigmatism were common. These results indicate that fear of impeding emmetropization should not refrain the clinician from providing adequate correction for refractive errors in young children with albinism.

Genetic landscape of forensic DNA phenotyping markers among Mediterranean populations

Forensic DNA Phenotyping can reveal the appearance of an unknown individual by predicting the External Visible Characteristics (EVC) from DNA obtained at the crime scene. Our aim is to characterize the genetic landscape of Human identification markers responsible for EVC among Mediterranean populations compared to other worldwide groups. We conducted an exhaustive search for genes involved in EVC variation. Then, variants located on these genes were extracted from public genotypic data of Mediterranean, American, African and East Asiatic populations. The genetic landscape of these Human identification markers, their allelic distribution and admixture analyses, were determined using plink, R and ADMIXTURE softwares. Our results showed that the Mediterranean populations appear close to the Mexican populations and distinguished from sub Saharan African populations living in the USA and from East Asiatic populations. We highlighted a total of 103454 common variants shared between the studied populations and among them, 25 common variants associated with EVC. Interestingly, genotype frequencies results showed that the rs17646946, rs13016869, rs977588, rs1805008 and rs2240751 variants located respectively in the TCHH, PRKCE, OCA2, MC1R and MFSD12 genes are significantly different between the Mediterranean and Asiatic populations. The genotype frequencies of the variants rs977589 and rs7179994 located in the OCA2 gene, and of rs12913832 and rs2240751 located respectively in HERC2 and MFSD12 genes are significantly different between the Mediterranean and American populations. Our work generates a large number of EVC variants that could be a valuable resource for future studies in the forensic field.

Reduction of lens size in PAX6-related aniridia

Heterozygous mutation of PAX6 in humans leads to congenital aniridia (OMIM 106210) which is typified by congenital iris and foveal defects, and later onset glaucoma, aniridic keratopathy, and cataract. Mice heterozygous for Pax6 mutations phenocopy many aspects of aniridia including the iris defects, keratopathy and cataract, although Pax6 mutant mice have small lenses, a phenotype which is not typically reported in human aniridia, perhaps due to difficulties in measuring lens diameter during typical ophthalmic examinations as the lens periphery is shielded by the iris. In order to overcome this, records of patients diagnosed with congenital aniridia between April 2015 and May 2021 at the Necker-Enfants Malades Hospital, and genetically confirmed with a disease-causing PAX6 variant, were retrospectively reviewed for those with normal axial length whose iris defects allowed visualization of the lens margins and corneal diameter to allow calculation of a lens/corneal diameter ratio. This value was compared with values obtained from a cohort of patients with Sjödell grade IV oculocutaneous albinism type 1 (OCA1; OMIM 203100) which allowed visualization of the lens periphery via iris transillumination. This analysis revealed that patients with congenital aniridia had a significantly lower lens/corneal ratio when compared to those with albinism, suggesting that humans haploinsufficient for PAX6, like mice, rats, frogs, and zebrafish, exhibit reductions in lens size.

The molecular landscape of oculocutaneous albinism in India and its therapeutic implications.

Oculocutaneous albinism is an inherited disorder of melanin biosynthesis, characterized by absent or reduced pigmentation of the skin, hair, and eyes. Molecular alterations of genes that cause non-syndromic albinism in Asian Indians are poorly characterized. This information would be useful for developing therapies for this disorder. We analyzed 164 persons with non-syndromic albinism, belonging to unrelated families from all parts of India, for molecular changes in the causative genes. Subjects with white hair, white skin, and red iris had their tyrosinase gene sequenced and were also tested by MLPA for deletions/duplications. Subjects with negative results or with darker skin, golden/brown or darker hair had sequencing of TYR, P, TYRP1, SLC45A2 and GPR143 genes. Pathogenic variants in TYR (OCA1) were observed in 139 (84.7%) patients, in the P gene (OCA2) in 20 (12.2%), in TYRP1 (OCA3) in two (1.2%), in SLC45A2 (OCA 4) in one (0.61%), and in GPR143 (X-linked ocular albinism) in two (1.2%) patients. Of 278 alleles with variants in TYR, 179 (64.3%) alleles had (p.R278*) alteration, suggesting the possibility of therapy with a stop codon readthrough molecule. We report 20 patients with 13 disease associated variants in the P gene and 18 novel pathogenic variants in TYR, P, TYRP1, SLC45A2 and GPR143 genes. The data are compared with those reported from India, Pakistan and rest of the world. The therapeutic options in albinism are briefly described, opening this field for future therapies.