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At least 19 recordsLinked to original sources
PubMed1978

Autosomal recessively inherited ocular albinism. A new form of ocular albinism affecting females as severely as males.

A new form of ocular albinism, autosomal recessively inherited ocular albinism (AROA), was studied in seven females and two males from five unrelated Caucasian kindreds. Affected patients have the impaired vision, translucent irides, congenital nystagmus, photophobia, albinotic fundi with hypoplasia of the fovea, and strabismus that are also found in X-linked ocular albinism (XOA). Unlike XOA, however, this form of ocular albinism is inherited as an autosomal recessive trait, with females affected as severely as males. Obligate heterozygotes of AROA lack the ocular abnormalities that are present in females heterozygous for XOA. Also, skin and hairbulb biopsy specimens do not reveal any abnormalities in patients with AROA, whereas giant pigment granules are found in patients heterozygous and hemizygous for XOA. The recognition of this disorder is imperative for proper diagnosis and responsible genetic counseling.

Adult↗
PubMed1992

Ocular albinism in a male with del (6)(q13-q15): candidate region for autosomal recessive ocular albinism?

We describe a boy with an interstitial deletion of 6(q13-q15) and include "coarse" facial features, upslanting palpebral fissures, thin vermilion border of the upper lip, elongated philtrum, developmental delay, and profound hypotonia. The child's eye findings, pedigree, paucity of maternal ocular changes, and lack of melanin macroglobules in the skin suggest that this individual's phenotype is clinically similar to that of autosomal recessive ocular albinism. Though it is possible that this deletion and his ophthalmic disorder are coincidental, we postulate that the ocular albinism may be due to hemizygosity for a paternally derived ocular albinism gene located on chromosome 6 in the region q13-q15. This patient's deletion is secondary to a recombination of a maternal intrachromosomal inverted insertion of this region. Of the 7 reported 6q1 deletions, this is the only case that is due to a familial chromosome rearrangement.

Albinism, Ocular↗
PubMed1978

X-linked ocular albinism in Blacks. Ocular albinism cum pigmento.

X-linked ocular albinism can be an unsuspected cause of congenital nystagmus in blacks. In this study, eight of ten black ocular albinos from two kindreds had nonalbinotic, moderately pigmented fundi and no transillumination of the iris. We refer to this paradoxical condition as "ocular albinism cum pigmento." The only constant ophthalmoscopic feature was a foveal hypoplasia. Biopsy of clinically normal skin to demonstrate giant pigment granules is the most accurate means of diagnosis.

Adolescent↗
PubMed1990

[Eumelanin and pheomelanin contents in hairs of healthy Japanese and patients with oculocutaneous albinism, and 5-S-cysteinyldopa and 5-hydroxy-6-methoxyindole-2-carboxylic acid levels in urine of oculocutaneous albinism].

The contents of eumelanin and pheomelanin in the scalp hairs of 4 Japanese patients with total albinism (3 tyrosinase-positive and one negative) and 100 healthy Japanese were measured by the melanin microquantitation method of Ito and Fujita. The urinary 5-S-Cysteinyldopa (5-S-CD) and 5-Hydroxy-6-Methoxyindole-2-Carboxylic acid (5H6MI2C) contents in the 4 albino subjects were also determined. Our findings included that (1) Regardless of ge, black hairs of all the healthy subjects contained phemelanin at a level of about 5% of the total melanin contents. The hair color of the 3 tyrosinase-positive subjects was pale-yellow, and their hairs contained only pheomelanin. The hair color of the one tyrosinase-negative subject was white, and neither eumalanin nor pheomelanin could be detected. (2) Urinary 5H6M12C, an indicator of eumelanin production in the body, could not be detected in either the tyrosinase-positive or tyrosinase-negative subjects, while the urinary 5-S-CD content of the tyrosinase-negative subject was much lower than that of the tyrosinase-positive subjects. These results suggested that the yellow hair color of patients with tyrosinase-positive albinism is attributable to the production of only pheomelanin and that the urinary 5-S-CD content does not necessarily reflect the ability to produce melanin.

Adolescent↗
PubMed1979

Albinism.

There are seven forms of oculo-cutaneous albinism, which are all autosomal recessive: three are tyrosinase-negative (complete oculo-cutaneous albinism, Amish albinism, Hermansky-Pudlak syndrome) and four are tyrosinase-positive (incomplete oculo-cutaneous albinism, Chediak-Higashi syndrome, Cross syndrome, Bergsma's albinism). There are three forms of sex-linked albinism: ocular albinism, which is intermediary sex-linked, François-De Rouck syndrome and Ziprkowski syndrome, which show a generalized albinism and are recessive sex-linked. There are two principal forms of cutaneous albinism, one without deafness and the other with deafness (Waardenburg-Klein syndrome).

Albinism↗
PubMed1990

Red or rufous albinism in southern Africa.

Red or rufous albinism is a rare type of oculocutaneous albinism described, but not as yet fully investigated, in Africa and New Guinea. Twelve rufous albino subjects from 10 families participated in this preliminary study. The prevalence of rufous albinism was found to be approximately one in 8,580 among school children in the negroid population. The combination of the unusual red skin colour, ginger to reddish hair colour, low susceptibility to sun damage, and minimal visual problems, in affected individuals, suggested that they form a group which is distinct from the brown and other types of albinism. The mode of inheritance was found to be recessive. Tyrosinase assays showed that rufous albinos are tyrosinase positive and on electron microscopy studies normal melanosomes and melanocytes were observed in hair bulbs and skin. Visual evoked potential testing did not show the gross decussation abnormalities of the optic pathway detected in other types of albinism. Rufous albinism might be at one end of the spectrum of types of oculocutaneous albinism and, because affected people have such mild symptoms, their inclusion in this group might be debatable.

Adolescent↗
PubMed1991

Variable expression of vision in sibs with albinism.

Oculocutaneous albinism is defined by the presence of cutaneous and ocular hypopigmentation, the latter associated with nystagmus, iris transillumination, reduced retinal pigment, foveal hypoplasia, and misrouting of the optic fibers at the chiasm. The visual acuity is variable but almost always reduced. We report on two brothers with oculocutaneous albinism and markedly different visual acuity. One brother has a visual acuity of 20/100, while the second has similar cutaneous pigmentation and visual acuity of 20/20 and had not previously been recognized as having oculocutaneous albinism. Both brothers have foveal hypoplasia and misrouting of the optic fibers at the chiasm. Biochemical analysis suggests that this is a tyrosinase-related type of oculocutaneous albinism. This study demonstrates that careful observation of foveal development in relatives with normal vision is necessary to detect all individuals with albinism in a family. A suspected diagnosis of albinism may be confirmed when the visual-evoked potentials show excessive decussation of the optic fibers at the chiasm.

Adolescent↗
PubMed1990

Albinism and Hermansky-Pudlak syndrome in Puerto Rico.

Five types of oculocutaneous albinism and two types of ocular albinism were found among 349 Puerto Rican albinos. The most prevalent type of albinism was the Hermansky-Pudlak syndrome (HPS). HPS was observed in five of every six albinos in Puerto Rico. The prevalence of HPS was highest in the northwestern quarter of the island, affecting approximately one in 1,800 persons, and approximately one in 22 are carriers of the gene. HPS is an autosomal recessively inherited triad of a tyrosinase-positive type of albinism, a hemorrhagic diathesis due to storage pool deficient platelets and accumulation of ceroid in tissues. The pigmentary phenotype of HPS albinos resembled that of any other type of oculocutaneous or ocular albinism. The most reliable method of diagnosing HPS is by a deficiency of platelet dense bodies observed by electron microscopy. The accumulation of ceroid in the tissues is associated with fibrotic restrictive lung disease and granulomatous enteropathic disease. The enteropathic disorder resembles Crohn's disease and with few exceptions, had its onset after 13 years of age. The major causes of death were fibrotic restrictive pulmonary disease, hemorrhagic episodes and sequelae of granulomatous enteropathic disease. Menometrorrhagia was common in women with HPS. No immune deficiency was found in HPS patients. The majority of patients with HPS had visual acuities of 20/200 or worse and consequently were legally blind. Albinos of all types, including HPS, lacked binocular vision due to nearly complete crossing of the optic tracts.

Albinism, Ocular↗
PubMed1990

Hypoplastic corpus callosum in ocular albinism: indication of a global disturbance of neuronal migration.

Ocular albinism is distinguished from the more common oculocutaneous albinism by the presence of normal pigmentation of skin and hair in the former condition. Recent studies of ocular albinism have shown that the hypopigmentation of the optic fundus is associated with a number of anomalies of neuronal wiring involving the visual system. We present a patient with ocular albinism who also has a hypoplastic corpus callosum as determined by analysis of midsagittal magnetic resonance imaging scans. Previous studies of the hypoplastic corpus callosum indicate that this anomaly is a defect in neuronal migration as well. The finding of a hypoplastic corpus callosum in a patient with ocular albinism suggests a more generalized defect in neuronal migration not limited to the visual system.

Abnormalities, Multiple↗
PubMed1979

Partial oculocutaneous albinism in Mystromys albicaudatus: nonhomology with the Chediak-Higashi syndrome.

Partially albinic Mystromys albicaudatus were examined to determine if the condition in these animals was homologous with the Chediak-Higashi syndrome. Tissues and cells from partially albinic and normal Mystromys albicaudatus were studied by light and electron microscopy. No evidence of cytoplasmic granule enlargement, which is characteristic of the Chediak-Higashi syndrome, was detected in the cells of the partially albinic rats when compared to controls. It was concluded that the inherited condition of partial albinism of Mystromys albicaudatus was not homologous with the inherited partially albinic disease known as the Chediak-Higashi syndrome.

Albinism↗
PubMed1978

[Cytogenetics of albinism in polecats of the genus Putorius (Carnivora, Mustelidae)].

Karyotypes of two ferret species, Putorius eversmanni (2n = 38) and P. putorius (2n = 40), differ in a single Robertsonian rearrangement, resulting in decreased chromosome number in P. eversmanni. Interspecific hybrids from crosses between P. eversmanni and domesticated albino ferret P. putorius furo are fertile. Hybrid individuals have a chromosome set 2 = 39. Analysis of offspring from crosses of these hybrids showed that albinism is a recessive character. Offspring obtained from crosses between interspecific hybrid ferrets and between these hybrids and parental species was subjected to chromosome analysis. A statistically significant correlation was observed between the chromosome number and albinism. As a rule, albino hybrids have a chromosome number 2n = 40. This suggests that the locus, controlling albinism, is located at one of the two pairs of acrocentric chromsomes involved in Robertsonian rearrangement. The rare occurrence of albino hybrids with 2n = 39 may be attributed to recombination. According to our data, recombination probability is less than 0.5 which indicates that the albinism locus located near the centromere. Possible extrapolation of the data obtained for ferrets to other Mustelidae is discussed.

Albinism↗
PubMed2025

Multi-Omics Analysis of the Potential Mechanisms of Skin Albinism in Edangered Percocypris pingi: Abnormal Ubiquitination and Calcium Signal Inhibition.

Percocypris pingi is an endangered protected fish species in China. Its albino variants exhibit growth retardation and physiological abnormalities. Understanding its albinism mechanism holds significant scientific importance for molecular breeding programs and disease model development. This study integrated transcriptomic and proteomic analyses, combined with histopathological and molecular biological techniques, to systematically compare molecular differences in skin tissues between albino and wild-type P. pingi, with a focus on elucidating the multidimensional regulatory mechanisms underlying skin albinism. Our findings suggest that albinism in P. pingi is synergistically driven by hyperactivation of ubiquitin-mediated proteolysis (which suppressed TYR/TYRP1 enzymatic activity and disrupted the pH homeostasis of melanosomes), and inhibition of calcium signaling (which impeded melanin transport). This discovery provides novel insights into the mechanisms of pigment loss in fish species and offers a valuable reference for molecular breeding of endangered species as well as research on pigmentation-related disorders.

Animals↗
PubMed1991

Albinism--a clinician's low vision perspective.

Albinism is inherited as autosomal recessive, with one exception: Ocular albinism, which has an x-linked trait. Visual symptoms include photophobia, varying degrees of nystagmus, reduction in visual acuity from 20/30 to 20/400 and varying degrees of moderate to high amounts of corneal astigmatism. Albinism patients respond very well to low vision devices and glare filters.

Albinism, Ocular↗
PubMed1976

X-linked ocular albinism. An oculocutaneous macromelanosomal disorder.

Three unrelated kindreds with the Nettleship-Falls type of X-linked ocular albinism were studied. Postmortem examination of the eyes of an affected man revealed the presence of macromelanosomes in the pigment epithelia. Skin biopsy specimens of this patient, seven other affected male, and nine carrier female kindred members revealed the presence of Fontana-positive and dopa oxidase-positive macromelanosomes within the epidermis and dermis. Although clinically this disorder has been considered to be a form of albinism confined to the eyes, these findings indicate that an unusual disturbance in melanosome production characterized by macromelanosome formation affects the skin and the eyes. Histopathologic study of the skin is a useful adjunct in the diagnosis of X-linked ocular albinism, both in the affected and the carrier states. Linkage studies confirmed the close association of the Xg blood group with this disorder.

Adult↗
PubMed1992

Cloning and sequence analysis of the tyrosinase gene from a patient with tyrosinase-positive oculocutaneous albinism.

Tyrosinase is synthesized on membrane-bound ribosomes and transported into melanosomes through smooth endoplasmic reticulum and Golgi apparatus. Melanin polymers are produced only in melanosomes but never in smooth endoplasmic reticulum or Golgi apparatus, indicating that posttranslational modifications of tyrosinase are completed with melanosomes where tyrosinase becomes an active form. Based on a working hypothesis that tyrosinase-positive oculocutaneous albinism is a consequence of the structurally altered tyrosinase due to a point mutation in the gene of its gene coding for a glycosylation site or a membrane-binding site, which leads to the impairment in the posttranslational modification of tyrosinase and its catalytic activity, we have cloned the tyrosinase gene of one patient affected with tyrosinase-positive oculocutaneous albinism and determined its nucleotide sequence. Thus demonstrated all exons' nucleotide sequence of the patient's tyrosinase gene was found to be identical to that of the wild-type gene. The results indicate that the patient's tyrosinase itself is not altered. We therefore propose that the molecular basis for the development of tyrosinase-positive oculocutaneous albinism exists as a defect in other proteins required for the activation of tyrosinase or in other regions of the tyrosinase gene.

Adult↗
PubMed1990

A frequent tyrosinase gene mutation in classic, tyrosinase-negative (type IA) oculocutaneous albinism.

We have identified a tyrosinase gene mutation in several patients with classic, tyrosinase-negative (type IA) oculocutaneous albinism. This mutation, which results in a proline----leucine substitution at codon 81 of the tyrosinase polypeptide (EC 1.14.18.1), was observed in 20% (6 of 30) of oculocutaneous albinism alleles from independent probands, but it was not observed in any normal individuals. This mutation thus appears to be a frequent cause of tyrosinase-negative oculocutaneous albinism.

Albinism↗
PubMedDate not supplied

Albinism in Icelandic sheep.

A description is given of complete albinism in Icelandic sheep. The albino animals, which have occurred both among white and nonwhite strains of sheep, are pure white in color with pink eyes and impaired vision in bright light. The condition is shown to be autosomal, recessive, and is assumed to be caused by a mutation of C to c, thereby being homologous to albinism in rodents. Data on mating results are tabulated. This is believed to be the first case of albinism reported in sheep.

Albinism↗