Lessons of a day hospital: Comprehensive assessment of patients with albinism in a European setting

What Have We Learned about the Prevention of NMSC from Albino Patients from Malawi? Secondary Prevention Maintained over Time

BACKGROUND

We have conducted cooperative campaigns focusing on albino patients in a rural area of Malawi. What have we learned?

METHODS

Three surgical campaigns were performed in Nkhotakota district (2019-2023). Albino clinical and tumor characteristics were collected.

RESULTS

Between 22 and 75 albinos were evaluated in each campaign (mean age < 28 years old). Most patients did not use sunscreen in a way that provided optimal photoprotection. Regarding tumors, the proportion of basal and squamous cell carcinomas ranged from 1:1 to almost 2:1. Of 156 albino patients, 34 attended more than once. However, of the 19 patients with 30 tumors operated on in 2021, only seven were assessed the following year (12 were lost to follow-up). At least 14 albinos with locally advanced tumors were evaluated.

CONCLUSIONS

Distributing photoprotective clothing could be more efficient or perhaps an earlier measure of sunscreen in rural Africa as it does not require permanent repositioning. Very-high-risk patients (previous interventions with positive margins or high-risk tumors, intense actinic damage, and new tumors constantly appearing, especially those presenting SCCs) require close follow-up and treatment and represent our main target. Secondary prevention with Malawian collaboration and the use of teledermatology is essential for patient tracking, as they are able to offer curative treatments.

Clinical and mutational characteristics of oculocutaneous albinism type 7

The purpose of this paper is to expand on the phenotype of oculocutaneous albinism type 7 (OCA7). We described three patients with OCA7: two from a consanguineous family of Kurdish origin and one patient of Dutch origin. We compared them with all patients described to date in the literature. All newly described patients had severely reduced visual acuity (VA), nystagmus, hypopigmentation of the fundus, severe foveal hypoplasia, and chiasmal misrouting. None had iris translucency. All patients had normal pigmentation of skin and hair. We found one novel mutation in the Dutch patient: c.565G > A; p.(Gly189Ser). We compared our patients to the 15 described in the literature to date. All 18 patients had substantially pigmented skin and hair, very poor VA (0.4-1.3 logMAR), nystagmus, (mild) ocular hypopigmentation, foveal hypoplasia, and misrouting. Although pigmentation levels were mildly affected in OCA7, patients had a severe ocular phenotype with VA at the poorer end of the albinism spectrum, severe foveal hypoplasia, and chiasmal misrouting. OCA7 patients had a phenotype restricted to the eyes, and similar to that of X-linked ocular albinism. We therefore propose to rename the disorder in ocular albinism type 2. Unfolding the role of LRMDA in OCA7, may bring us a step closer in identifying the responsible factors for the co-occurrence of foveal hypoplasia and misrouting.

Oculocutaneous albinism type 4: Novel compound heterozygous mutations in the SLC45A2 gene in a Chinese case

BACKGROUND

Oculocutaneous albinism type 4 (OCA4) is a rare autosomal recessive disorder characterized by a reduction of pigmentation in skin, hair, and eyes, and OCA4 is mainly seen in the SLC45A2 gene variants.

OBJECTIVE

To report a Chinese patient suspected of oculocutaneous albinism and identify the causing mutation.

METHODS

Genomic DNA was extracted from the peripheral blood samples of the patient, his parents, and elder brother. Whole exome sequencing was performed in the family, and Sanger sequencing was then used to verify the mutations.

RESULTS

Compound heterozygous variants, c.1304C>A (p.S435Y) and c.301C>G (p.R101G) in SLC45A2 gene, were detected in the proband, which were inherited from his father and mother respectively. Based on the ACMG guidelines, we can interpret the c.1304C>A (p.S435Y) variant as a suspected pathogenic variant and the c.301C>G (p.R101G) variant as a clinically significant unspecified variant. The diagnosis of OCA4 is confirmed.

CONCLUSION

We firstly reported this case of OCA4 with the compound heterozygous variants in the SLC45A2 gene. Our findings further enrich the reservoir of SLC45A2 mutations in OCA4.

MIR204 n.37C>T variant as a cause of chorioretinal dystrophy variably associated with iris coloboma, early-onset cataracts and congenital glaucoma

Four members of a three-generation Czech family with early-onset chorioretinal dystrophy were shown to be heterozygous carriers of the n.37C>T in MIR204. The identification of this previously reported pathogenic variant confirms the existence of a distinct clinical entity caused by a sequence change in MIR204. Chorioretinal dystrophy was variably associated with iris coloboma, congenital glaucoma, and premature cataracts extending the phenotypic range of the condition. In silico analysis of the n.37C>T variant revealed 713 novel targets. Additionally, four family members were shown to be affected by albinism resulting from biallelic pathogenic OCA2 variants. Haplotype analysis excluded relatedness with the original family reported to harbour the n.37C>T variant in MIR204. Identification of a second independent family confirms the existence of a distinct MIR204-associated clinical entity and suggests that the phenotype may also involve congenital glaucoma.

Oculocutaneous albinism: epidemiology, genetics, skin manifestation, and psychosocial issues

Oculocutaneous albinism (OCA) is a group of rare, inherited disorders associated with reduced melanin biosynthesis. Clinical manifestations of the eight known subtypes of OCA include hypopigmented skin, eyes, and hair and ocular manifestations, such as decreased visual acuity and nystagmus. OCA affects people globally but is most prevalent in African countries. Individuals with oculocutaneous albinism lack UV protection and are prone to skin damage and skin cancers. For many African albino individuals, there are significant challenges in seeking treatment for skin cancer and preventing sun damage due to psychosocial factors and poor education. This review summarizes the current understanding of the epidemiology, genetics, and clinical manifestations of OCA. We also discuss the medical and psychosocial challenges that affect individuals with OCA and the current landscape of albinism treatment modalities. The extent of the psychosocial challenges needs to be better understood and additional educational interventions may improve quality of life for people with albinism.

OCA7 is a melanosome membrane protein that defines pigmentation by regulating early stages of melanosome biogenesis

Mutations in C10orf11 (oculocutaneous albinism type 7 [OCA7]) cause OCA, a disorder that presents with hypopigmentation in skin, eyes, and hair. The OCA7 pathophysiology is unknown, and there is virtually no information on the OCA7 protein and its cellular function. Here, we discover that OCA7 localizes to the limiting membrane of melanosomes, the specialized pigment cell organelles where melanin is synthesized. We demonstrate that OCA7 is recruited through interaction with a canonical effector-binding surface of melanosome proteins Rab32 and Rab38. Using newly generated OCA7-KO MNT1 cells, we show OCA7 regulates overall melanin levels in a melanocyte autonomous manner by controlling melanosome maturation. Importantly, we found that OCA7 regulates premelanosome protein (PMEL) processing, impacting fibrillation and the striations that define transition from melanosome stage I to stage II. Furthermore, the melanosome lumen of OCA7-KO cells displays lower pH than control cells. Together, our results reveal that OCA7 regulates pigmentation through two well-established determinants of melanosome biogenesis and function, PMEL processing, and organelle pH.

Oculo-Cutaneous Albinism Type 4 (OCA4): Phenotype-Genotype Correlation

Albinism is a genetic disorder, present worldwide, caused by mutations in genes affecting melanin production or transport in the skin, hair and eyes. To date, mutations in at least 20 different genes have been identified. Oculo-cutaneous Albinism type IV (OCA4) is the most frequent form in Asia but has been reported in all populations, including Europeans. Little is known about the genotype-phenotype correlation. We identified two main phenotypes via the analysis of 30 OCA4 patients with a molecularly proven diagnosis. The first, found in 20 patients, is clinically indistinguishable from the classical OCA1 phenotype. The genotype-to-phenotype correlation suggests that this phenotype is associated with homozygous or compound heterozygous nonsense or deletion variants with frameshift leading to translation interruption in the SLC45A2 gene. The second phenotype, found in 10 patients, is characterized by very mild hypopigmentation of the hair (light brown or even dark hair) and skin that is similar to the general population. In this group, visual acuity is variable, but it can be subnormal, foveal hypoplasia can be low grade or even normal, and nystagmus may be lacking. These mild to moderate phenotypes are associated with at least one missense mutation in SLC45A2.

Amelanotic/hypopigmented melanoma in a sibship with oculocutaneous albinism

Oculocutaneous albinism (OCA) is a rare condition characterized by hypopigmentation. A female proband and her sister, both with primary amelanotic/hypopigmented melanoma, underwent three-dimensional total-body photography and dermoscopy. Both sisters had exome sequencing along with their brother, who had OCA but no history of melanoma. Imaging analysis was consistent with OCA in terms of individual typology angle scores, degree of sun damage, and high naevus counts. Exome data filtered for variants in known OCA and melanoma/naevi susceptibility genes (n = 98) found all siblings were compound heterozygous for TYR mutations (Arg402Ter and Val275Phe), previously reported as causative OCA variants. A rare missense variant in PARP1 (p.Pro377Ser) was solely present in the melanoma-unaffected brother, which is noteworthy as this was previously reported as potentially protective in a familial melanoma pedigree positive for CDKN2A mutations. Evaluation and confirmation of functional impact in larger cohorts could personalize melanoma screening in OCA.

Expanding the Spectrum of Oculocutaneous Albinism: Does Isolated Foveal Hypoplasia Really Exist?

Oculocutaneous albinism is an autosomal recessive disorder characterized by the presence of typical ocular features, such as foveal hypoplasia, iris translucency, hypopigmented fundus oculi and reduced pigmentation of skin and hair. Albino patients can show significant clinical variability; some individuals can present with only mild depigmentation and subtle ocular changes. Here, we provide a retrospective review of the standardized clinical charts of patients firstly addressed for evaluation of foveal hypoplasia and slightly subnormal visual acuity, whose diagnosis of albinism was achieved only after extensive phenotypic and genotypic characterization. Our report corroborates the pathogenicity of the two common TYR polymorphisms p.(Arg402Gln) and p.(Ser192Tyr) when both are located in trans with a pathogenic TYR variant and aims to expand the phenotypic spectrum of albinism in order to increase the detection rate of the albino phenotype. Our data also suggest that isolated foveal hypoplasia should be considered a clinical sign instead of a definitive diagnosis of an isolated clinical entity, and we recommend deep phenotypic and molecular characterization in such patients to achieve a proper diagnosis.

Identification of 12 OCA Cases in Chinese Population and Two Novel Variants

OCA (oculocutaneous albinism) refers to a group of heterogeneous congenital disorders of which the common manifestations are variable degrees of cutaneous hypopigmentation and significant visual impairment, including poor visual acuity, photophobia, and nystagmus. Molecular analysis may elucidate its pathogenesis and be in favor of accurate diagnosis. High-throughput sequencing and Sanger sequencing were performed to detect mutational alleles and in silico analysis was performed for prediction of variant pathogenicity. Ten TYR-related and two OCA2-related patients were identified with 16 different variants with potential pathogenicity. Two novel missense variants [TYR: c.623T > G, p(Leu208Arg) and OCA2: c.1325A > G, p(Asn442Ser)] are identified in this study, and three OCA cases are reported for the first time in Chinese population based on their associated variants. Analysis of crystal structures of TYR ortholog and its paralog TYRP1 suggests that the substitution of Leu²⁰⁸ may have an impact on protein stability. This study may facilitate OCA diagnosis by expanding the mutational spectrum of TYR and OCA2 as well as further basic studies about these two genes.

Ophthalmological Manifestations of Oculocutaneous and Ocular Albinism: Current Perspectives

Albinism describes a heterogeneous group of genetically determined disorders characterized by disrupted synthesis of melanin and a range of developmental ocular abnormalities. The main ocular features common to both oculocutaneous albinism (OCA), and ocular albinism (OA) include reduced visual acuity, refractive errors, foveal hypoplasia, congenital nystagmus, iris and fundus hypopigmentation and visual pathway misrouting, but clinical signs vary and there is phenotypic overlap with other pathologies. This study reviews the prevalence, genetics and ocular manifestations of OCA and OA, including abnormal development of the optic chiasm. The role of visual electrophysiology in the detection of chiasmal dysfunction and visual pathway misrouting is emphasized, highlighting how age-associated changes in visual evoked potential (VEP) test results must be considered to enable accurate diagnosis, and illustrated further by the inclusion of novel VEP data in genetically confirmed cases. Differential diagnosis is considered in the context of suspected retinal and other disorders, including rare syndromes that may masquerade as albinism.

Evidence that the Ser192Tyr/Arg402Gln in cis Tyrosinase gene haplotype is a disease-causing allele in oculocutaneous albinism type 1B (OCA1B)

Oculocutaneous albinism type 1 (OCA1) is caused by pathogenic variants in the TYR (tyrosinase) gene which encodes the critical and rate-limiting enzyme in melanin synthesis. It is the most common OCA subtype found in Caucasians, accounting for ~50% of cases worldwide. The apparent 'missing heritability' in OCA is well described, with ~25-30% of clinically diagnosed individuals lacking two clearly pathogenic variants. Here we undertook empowered genetic studies in an extensive multigenerational Amish family, alongside a review of previously published literature, a retrospective analysis of in-house datasets, and tyrosinase activity studies. Together this provides irrefutable evidence of the pathogenicity of two common TYR variants, p.(Ser192Tyr) and p.(Arg402Gln) when inherited in cis alongside a pathogenic TYR variant in trans. We also show that homozygosity for the p.(Ser192Tyr)/p.(Arg402Gln) TYR haplotype results in a very mild, but fully penetrant, albinism phenotype. Together these data underscore the importance of including the TYR p.(Ser192Tyr)/p.(Arg402Gln) in cis haplotype as a pathogenic allele causative of OCA, which would likely increase molecular diagnoses in this missing heritability albinism cohort by 25-50%.

The Phenotypic and Mutational Spectrum of the FHONDA Syndrome and Oculocutaneous Albinism: Similarities and Differences

Purpose

The purpose of this study was to further expand the mutational spectrum of the Foveal Hypoplasia, Optic Nerve Decussation defect, and Anterior segment abnormalities (FHONDA syndrome), to describe the phenotypic spectrum, and to compare it to albinism.

Subjects and Methods

We retrospectively collected molecular, ophthalmic, and electrophysiological data of 28 patients molecularly confirmed with FHONDA from the Netherlands (9), Israel (13), France (2), and the United States of America (4). We compared the data to that of 133 Dutch patients with the 3 most common types of albinism in the Netherlands: oculocutaneous albinism type 1 (49), type 2 (41), and ocular albinism (43).

Results

Patients with FHONDA had a total of 15 different mutations in SLC38A8, of which 6 were novel. Excluding missing data, all patients had moderate to severe visual impairment (median visual acuity [VA] = 0.7 logMAR, interquartile range [IQR] = 0.6-0.8), nystagmus (28/28), and grade 4 foveal hypoplasia (17/17). Misrouting was present in all nine tested patients. None of the patients had any signs of hypopigmentation of skin and hair. VA in albinism was better (median = 0.5 logMAR, IQR = 0.3-0.7, P 0.006) and the phenotypes were more variable: 14 of 132 without nystagmus, foveal hypoplasia grades 1 to 4, and misrouting absent in 16 of 74.

Conclusions

Compared to albinism, the FHONDA syndrome appears to have a more narrow phenotypic spectrum, consisting of nonprogressive moderately to severely reduced VA, nystagmus, severe foveal hypoplasia, and misrouting. The co-occurrence of nystagmus, foveal hypoplasia, and misrouting in the absence of hypopigmentation implies that these abnormalities are not caused by lack of melanin, which has important implications for understanding the pathogenesis of these features.

Evaluation of the acceptance and efficacy of a bespoke sun protection package for persons with oculocutaneous albinism living in Malawi

INTRODUCTION

Skin cancer is the main cause of death in persons with albinism (PWA) in Africa. Education would minimize sun damage.

OBJECTIVE

To evaluate the efficacy and acceptance of a photoprotection educative and sunscreen (Umozi Max) package designed for PWA in reducing sunburns and skin cancer.

PATIENTS AND METHODS

A multicenter, noncontrolled, before-and-after, interventional study was conducted in PWA > 12 years of age, from February to May, 2019, in Malawi. During the baseline and the follow-up visits (at 8 and 15 weeks), subjects received an educational program designed to PWA and use of Umozi Max. At every visit, photoprotection behavior and knowledge were checked and cutaneous lesions were recorded. Univariate and bivariate analysis were performed.

RESULTS

A total of 210 PWA were analyzed, 50% males, with a mean age of 24.5 (SD 11.29) years. The percentage of people using sun protective clothing increased from 80% to 100% and sunscreen from 81.9% to 99.5%. People avoiding the midday sun increased by 38.9% (P < 0.05). Participants that erroneously applied the sunscreen at night diminished from 40% to 4% (P < 0.001). Absent erythema on the face increased from 40% to 90% (P < 0.05). The percentage of patients with actinic keratoses (AK) on all locations significantly decreased during the study. All the participants preferred Umozi Max to previously used sunscreens. The satisfaction with the program was unanimous.

CONCLUSION

The educational program enhanced the use of all photoprotection measures, improved behaviors, and decreased the incidence of solar erythema and contributed to decreasing the incidence of new AKs.

Prevalence of premalignant and malignant skin lesions in oculocutaneous albinism patients

OBJECTIVE

Oculocutaneous albinism describes a group of pigmentary disorders that lead to skin sensitivity and predisposition to skin malignances.

AIMS

To analyze clinical and epidemiological data in oculocutaneous albinism patients and to determine the prevalence of malignant skin lesions, assessing possible risk factors for skin cancer.

METHODS

Cross-sectional study evaluating epidemiological data, habits of sun exposure and sun protection, and clinical examination of albino patients followed in a reference dermatology outpatient clinic in Brasil. Our primary outcome was the occurrence of malignant skin lesions in biopsied tissues.

RESULTS

Of 74 patients analyzed, 11 (15%) had one or more suspicious lesions and were biopsied, of which 8 (72.7%) patients presented with basal cell carcinomas, 7 (63.3%) presented with squamous cell carcinoma, and 1 (9%) presented with melanoma. Moreover, 32(43%) patients presented with actinic keratosis. Age, female gender, previous history of sunburn, history of malignant lesions and history of sun exposure without photoprotection were associated with the presence of malignant lesions.

LIMITATIONS

Unicentric, non-aleatory sample.

CONCLUSIONS

There was a high prevalence of malignant and pre-malignant lesions in this population. Some potentially modifiable risk factors were associated with the occurrence of malignant skin lesions.

Evident hypopigmentation without other ocular deficits in Dutch patients with oculocutaneous albinism type 4

To describe the phenotype of Dutch patients with oculocutaneous albinism type 4 (OCA4), we collected data on pigmentation (skin, hair, and eyes), visual acuity (VA), nystagmus, foveal hypoplasia, chiasmal misrouting, and molecular analyses of nine Dutch OCA4 patients from the Bartiméus Diagnostic Center for complex visual disorders. All patients had severely reduced pigmentation of skin, hair, and eyes with iris transillumination over 360 degrees. Three unrelated OCA4 patients had normal VA, no nystagmus, no foveal hypoplasia, and no misrouting of the visual pathways. Six patients had poor visual acuity (0.6 to 1.0 logMAR), nystagmus, severe foveal hypoplasia and misrouting. We found two novel variants in the SLC45A2 gene, c.310C > T; (p.Pro104Ser), and c.1368 + 3_1368 + 9del; (p.?). OCA4 patients of this Dutch cohort all had hypopigmentation of skin, hair, and iris translucency. However, patients were either severely affected with regard to visual acuity, foveal hypoplasia, and misrouting, or visually not affected at all. We describe for the first time OCA4 patients with an evident lack of pigmentation, but normal visual acuity, normal foveal development and absence of misrouting. This implies that absence of melanin does not invariably lead to foveal hypoplasia and abnormal routing of the visual pathways.

Management of albinism: French guidelines for diagnosis and care

Albinism is a worldwide genetic disorder caused by mutations in at least 20 genes, identified to date, that affect melanin production or transport in the skin, hair and eyes. Patients present with variable degrees of diffuse muco-cutaneous and adnexal hypopigmentation, as well as ocular features including nystagmus, misrouting of optic nerves and foveal hypoplasia. Less often, albinism is associated with blood, immunological, pulmonary, digestive and/or neurological anomalies. Clinical and molecular characterizations are essential in preventing potential complications. Disease-causing mutations remain unknown for about 25% of patients with albinism. These guidelines have been developed for the diagnosis and management of syndromic and non-syndromic forms of albinism, based on a systematic review of the scientific literature. These guidelines comprise clinical and molecular characterization, diagnosis, therapeutic approach and management.

Skin cancers in people with albinism in Togo in 2019: results of two rounds of national mobile skin care clinics

Background

In people with albinism (PWA), the deficiency of melanin increase the risk of skin cancers. The aim of this study was to determine the prevalence of skin cancers and characteristics of these detected skin cancers (histological types, localization) in PWA in 10 cities in Togo in 2019.

Methods

This is a cross-sectional study of medical records of PWA systematically examined during two mobile skin care clinics in 2019, as part of a programme for the prevention and management of skin cancers in these subjects.

Results

During the study period, 280 (95.2%) of the 294 PWA consulted, had developed skin lesions. Of the 280 PWA, the pathological reports from the medical records of 33 patients (11.8%; (95%CI = [8.2–16.2]) had concluded to non-melanoma skin cancers. The mean age of these 33 patients was 38.6 ± 15.2 years and the sex-ratio was 1. Their occupations were mainly resellers (21.2%), traders (15.2%) and farmers (12.2%). In the 33 patients, 54 cases of non-melanoma skin cancers were identified, with some patients having more than one tumor, and some of them having more than one (histologically confirmed) diagnosis. These 54 non-melanoma skin cancers were divided into 21 cases of invasive squamous cell carcinomas, 2 cases of Bowen’s disease and 31 cases of basal cell carcinomas. These non-melanoma skin cancers mainly occurred in the head and neck (33 cases; 61.1%), the upper limbs (15 cases; 27, 8%) and the trunk (4 cases; 7.4%).

Conclusion

The results of this study show a high prevalence of skin cancers among PWAs in Togo in 2019, only non-melanoma skin cancers. In addition, they illustrate the role of ultraviolet rays with regard to the localization of skin cancers and the occupations of patients. Popularization and compliance with photo protection measures, systematic and regular examination of the skin of these PWAs will allow early detection and treatment of these skin cancers.

Dermatological and epidemiological profile of patients with albinism in Togo in 2019: results of two consultation campaigns

BACKGROUND

People with albinism (PWA) are targets of prejudice and social exclusion and have limited access to specialized medical care and resources. Our study aimed to describe the epidemiological and dermatological profile of PWA in Togo.

METHOD

We carried out a cross-sectional study of 294 medical records of PWA systematically examined during two mobile skin care clinics in 2019.

RESULTS

The mean age of the patients was 22 ± 16.5 years, and the gender ratio (M/F) was 1. A family history of albinism was reported in 27.9% of cases, and consanguinity between the parents was found in 24.1% of PWA. Dermatological lesions on physical examination were present in 95.2% of PWA. These lesions were elastosis/wrinkles (82.9%), ephelides (79.6%), actinic keratoses (60.0%), actinic cheilitis (50.0%), and cutaneous carcinomas (11.8%). The mean age of PWA with skin carcinomas was 38.6 years. Fifty-four cases of cutaneous carcinomas had been diagnosed (31 cases of basal cell carcinoma, 21 cases of squamous cell carcinoma, and 2 cases of Bowen's disease) and were located mainly in the cephalic region (61.1%) and upper limbs (27.8%). Cryotherapy and/or excisional biopsies were the treatments for premalignant and malignant lesions. All PWA were sensitized on sun protection.

CONCLUSIONS

This study shows the basic picture of dermatological characteristics of PWA with a high frequency of photo-induced lesions and skin cancers. The popularization and respect of photoprotection measures and regular skin examination of these PWA for early detection and management of lesions will reduce their morbidity and mortality.

Non-syndromic Oculocutaneous Albinism: Novel Genetic Variants and Clinical Follow Up of a Brazilian Pediatric Cohort

Oculocutaneous albinism (OCA) is a genetic disorder characterized by skin, hair, and eye hypopigmentation due to a reduction or absence of melanin. Clinical manifestations include vision problems and a high susceptibility to skin cancer. In its non-syndromic form, OCA is associated with six genes and one chromosomal region. Because OCA subtypes are not always clinically distinguishable, molecular analysis has become an important tool for classifying types of OCA, which facilitates genetic counseling and can guide the development of new therapies. We studied eight Brazilian individuals aged 1.5–18 years old with clinical diagnosis of OCA. Assessment of ophthalmologic characteristics showed results consistent with albinism, including reduced visual acuity, nystagmus, and loss of stereoscopic vision. We also observed the appearance of the strabismus and changes in static refraction over a 2-year period. Dermatologic evaluation showed that no participants had preneoplastic skin lesions, despite half of the participants reporting insufficient knowledge about skin care in albinism. Whole-exome and Sanger sequencing revealed eight different mutations: six in the TYR gene and two in the SLC45A2 gene, of which one was novel and two were described in a population study but were not previously associated with the OCA phenotype. We performed two ophthalmological evaluations, 2 years apart; and one dermatological evaluation. To the best of our knowledge, this is the first study to perform clinical follow-up and genetic analysis of a Brazilian cohort with albinism. Here, we report three new OCA causing mutations.

Clinical and genetic variability in children with partial albinism

Individuals who have ocular features of albinism and skin pigmentation in keeping with their familial background present a considerable diagnostic challenge. Timely diagnosis through genomic testing can help avert diagnostic odysseys and facilitates accurate genetic counselling and tailored specialist management. Here, we report the clinical and gene panel testing findings in 12 children with presumed ocular albinism. A definitive molecular diagnosis was made in 8/12 probands (67%) and a possible molecular diagnosis was identified in a further 3/12 probands (25%). TYR was the most commonly mutated gene in this cohort (75% of patients, 9/12). A disease-causing TYR haplotype comprised of two common, functional polymorphisms, TYR c.[575 C > A;1205 G > A] p.[(Ser192Tyr);(Arg402Gln)], was found to be particularly prevalent. One participant had GPR143-associated X-linked ocular albinism and another proband had biallelic variants in SLC38A8, a glutamine transporter gene associated with foveal hypoplasia and optic nerve misrouting without pigmentation defects. Intriguingly, 2/12 individuals had a single, rare, likely pathogenic variant in each of TYR and OCA2 - a significant enrichment compared to a control cohort of 4046 individuals from the 100,000 genomes project pilot dataset. Overall, our findings highlight that panel-based genetic testing is a clinically useful test with a high diagnostic yield in children with partial/ocular albinism.

Albinism: epidemiology, genetics, cutaneous characterization, psychosocial factors

Oculocutaneous albinism is an autosomal recessive disease caused by the complete absence or decrease of melanin biosynthesis in melanocytes. Due to the reduction or absence of melanin, albinos are highly susceptible to the harmful effects of ultraviolet radiation and are at increased risk of actinic damage and skin cancer. In Brazil, as in other parts of the world, albinism remains a little known disorder, both in relation to epidemiological data and to phenotypic and genotypic variation. In several regions of the country, individuals with albinism have no access to resources or specialized medical care, and are often neglected and deprived of social inclusion. Brazil is a tropical country, with a high incidence of solar radiation during the year nationwide. Consequently, actinic damage and skin cancer occur early and have a high incidence in this population, often leading to premature death. Skin monitoring of these patients and immediate therapeutic interventions have a positive impact in reducing the morbidity and mortality associated with this condition. Health education is important to inform albinos and their families, the general population, educators, medical professionals, and public agencies about the particularities of this genetic condition. The aim of this article is to present a review of the epidemiological, clinical, genetic, and psychosocial characteristics of albinism, with a focus in skin changes caused by this rare pigmentation disorder.

Dermatological and Epidemiological Profiles of Patients with Albinism in São Paulo, Brazil, between 2010 and 2017: A Cross-Sectional Study

INTRODUCTION

Oculocutaneous albinism is an autosomal recessive disease caused by complete absence of or decrease in melanin biosynthesis in melanocytes. Due to the reduction or absence of melanin, albinos are highly susceptible to the harmful effects of ultraviolet radiation and are at greater risk of actinic damage and skin cancer. There are no epidemiological data on the incidence of albinism in Brazil.

OBJECTIVE

To analyze the clinical and epidemiological profile of patients with albinism treated by the Pró-Albino Program of the Dermatology Clinic of Santa Casa de Misericórdia from its beginning in 2010 until 2017.

METHODS

In this cross-sectional study, the records of all consecutive albino patients admitted to the service in the study period were reviewed. Sociodemographic data, family history, and dermatological clinical data were collected.

RESULTS

Between March 2010 and April 2017, 191 patients were admitted, of whom 109 were female (57.07%) and the age range was 0-92 years, with >30% under the age of 18 years. Consanguinity among the parents was confirmed by 26% of the patients. Unprotected sun exposure was reported by 109 (57.07%), and 138 (72.25%) had a history of sunburn. Of the 146 records with information, 38 had skin cancer (26%), with a mean age of 47.4 (p < 0.0001); the youngest patient diagnosed with a cutaneous tumor was 23 years old. The prevalence of actinic damage was high. There was information on solar elastosis and actinic keratosis in 148 medical records, of which 96 (64.8%) patients had elastosis and 75 (50.67%) keratoses. Elastosis, keratosis, and skin cancer were significantly associated with age, unprotected sun exposure, and sunburn (p < 0.05). Of the 37 (26% of the sample of 146) patients with a previous or current history of skin cancer, it was possible to identify the histological type in 29 (13 men and 16 women); of these, 18 (62%) were basal cell carcinomas (BCC), 15 (51%) were squamous cell carcinomas (SCC), and 2 (7%) were melanomas. Of these, 4 cases (14%) presented the 2 types of carcinoma (BCC and SCC), and the 2 that had a diagnosis of melanoma also had BCC. Some patients had multiple ulcerated tumors. The tumor site was preferentially in the head and neck (43%), trunk (37%) and limbs (20%).

CONCLUSIONS

Albinos represent a risk group for skin cancer and other actinic lesions. These lesions were found to be prevalent in the albinos seen by the program and probably reflect the characteristics found in the Brazilian albino population. Access to health care, especially through multidisciplinary programs that enable the diagnosis and early treatment of these lesions, health education, and the use of photoprotective measures can reduce morbidity and mortality and improve the quality of life of patients with this rare genetic condition.

Comprehensive analysis of spectral distribution of a large cohort of Chinese patients with non-syndromic oculocutaneous albinism facilitates genetic diagnosis

Non-syndromic oculocutaneous albinism (nsOCA) is a group of genetically heterogeneous autosomal recessive disorders with complete lack or decrease pigmentation in skin, hair, and eyes. TYR, OCA2, TYRP1, SLC45A2, SLC24A5, and LRMDA were reported to cause OCA1-4 and OCA6-7, respectively. By sequencing all the known nsOCA genes in 114 unrelated Chinese nsOCA patients combined with In silico analyses, splicing assay, and classification of variants according to the standards and guidelines of American College of Medical Genetics and Genomics, we detected seventy-one different OCA-causing variants separately in TYR, OCA2, SLC45A2, and SLC24A5, including thirty-one novel variants (13 in TYR, 11 in OCA2, and 7 in SLC45A2). This study shows that OCA1 is the most common (75/114) and OCA2 ranks the second most common (16/114) in Chinese. 99 patients of our cohort were caused by variants of all the known nsOCA genes. Cutaneous phenotypes of OCA1, OCA2, and OCA4 patients were shown in this study. The second OCA6 case in China was identified here. These data expand the spectrum of OCA variants as well phenotype and facilitate clinical implement of Chinese OCA patients.

Mild form of oculocutaneous albinism type 1: phenotypic analysis of compound heterozygous patients with the R402Q variant of the TYR gene

AIM

Oculocutaneous albinism type 1 (OCA1) is due to TYR mutations. c.1205G>A/p.Arg402Gln (R402Q) is a thermosensitive variant of the TYR gene that has been reported to be responsible for mild forms of OCA1. The aim of our study was to define the phenotype associated with this variant.

METHODS

In our retrospective series, among 268 patients diagnosed with OCA1, 122 (45.5%) harboured one pathogenic variant of TYR, and the R402Q variant ensured to be in trans by segregation analysis in 69 patients (25.7%), constituting the 'R402Q-OCA1' group. 146 patients harboured two pathogenic variants of the TYR gene other than R402Q. Clinical records were available for 119 of them, constituting the 'Classical-OCA1' group.

RESULTS

Most R402Q-OCA1 patients presented with white or yellow-white hair at birth (71.43%), blond hair later (46.97%), a light phototype but with residual pigmentation (69.64%), and blue eyes (76.56%). Their pigmentation was significantly higher than in the classical-OCA1 group. All patients from the R402Q-OCA1 group presented with ocular features of albinism. However the prevalence of photophobia (78.13%) and iris transillumination (83.87%) and the severity scores of iris transillumination, retinal hypopigmentation and foveal hypoplasia were lower in the R402Q-OCA1 group. Visual acuity was higher in the R402Q-OCA1 group (0.38±0.21 logarithm of the minimum angle of resolution vs 0.76±0.24). Investigations concerning a possible additive effect of the c.575C>A/p.Ser192 (S192Y) variant of TYR in cis with R402Q, suggested by others, showed no significant impact on the phenotype.

CONCLUSION

The R402Q variant leads to variable but generally mild forms of albinism whose less typical presentation may lead to underdiagnosis.