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PubMed1980

Yellow mutant albinism: cytochemical, ultrastructural, and genetic characterization suggesting multiple allelism.

This report describes three sisters, including monozygotic (MZ) twins, with clinical, ultrastructural, and histochemical features typical of yellow mutant albinism; This form of albinism is clinically similar to the tyrosinase-positive type, but hair bulbs showed (1) organelles similar to red hair pheomelanosomes and (2) absence of tyrosinase activity. Classical tyrosinase-negative albinism was found in a maternal cousin of the probands. Pedigree analysis of this family suggests multiple alleles occupying a single locus.

Adult↗
PubMed1996

Might the refractive state in oculocutaneous albino patients be a clue for distinguishing between tyrosinase-positive and tyrosinase-negative forms of oculocutaneous albinism?

In oculocutaneous albinism (OCA), one can distinguish between a tyrosinase-negative form (no residual activity of the enzyme tyrosinase) and a tyrosinase-positive form (with detectable residual enzymatic activity) and their respective subtypes. In infancy and early childhood the clinical discrimination between tyrosinase-positive OCA and tyrosinase-negative OCA can be very difficult. To date, only the hair-bulb L-dopa incubation test has been helpful in discriminating between the tyrosinase (ty)-negative and ty-positive forms of OCA. In 68 patients with albinism of the eye, 24 had an oculocutaneous form of albinism. We determined the ty relationship either by the L-dopa incubation test (younger patients) or by clinical appearance (older patients). We determined the full cycloplegic refraction in all patients and looked for a possible correlation of the refraction with the ty relationship. Our data suggest that an OCA patient with a hyperopic refractive error of > 4.0 D might have a ty-positive form of OCA. A patient with a moderate to high degree of myopia is more likely to have a ty-negative form of OCA. Determination of ty relationship is more reliable in patients with high degrees of hyperopia and, therefore, in patients with a ty-positive form of OCA. Statistical evaluation of the data was not possible in a sensible way due to the small number of patients involved in the present study.

Adolescent↗
PubMed1990

Comparative genetics of albinism.

Albinism in laboratory mammals is equivalent to human tyrosinase-negative oculocutaneous albinism, and thus the result of recessive mutation in the structural locus for tyrosinase (TYR), which prevents melanin biosynthesis. In the mouse, eight mutant alleles are now known at this locus, with differing effects on eye colour and on the degree of reduction in eumelanin and phaeomelanin pigmentation. Three of these alleles, namely chinchilla, himalayan (acromelanistic) and albino (c) itself, have also been recognized in a number of other species but only albino has been identified in man so far. The himalayan allele (equivalent to Siamese in the cat) is of particular interest because it converts tyrosinase into a thermolabile form, with greater production of melanin in colder areas of the body. The optic track misrouting found in human albinos also occurs in albino alleles in other mammals, which may also show reduced activity and stress responses. The TYR locus is on human chromosome 11, which now has at least 11 loci with homologues on mouse 7. However, their order is markedly different in the two species. For instance, c and Hbb (beta-globin), which are closely linked in mouse, rabbit, cat etc., are far apart on human 11q and 11p respectively. Moreover, some loci (e.g., Fes and Mod-2) which are close to c in the mouse appear to be on human chromosomes other than 11. This extensive chromosomal restructuring in mammalian evolution means that the effects of human albino deletions may differ greatly from those studied in the mouse, which are associated with defects of kidney, liver and thymus. Tyrosinase-positive albinos or near-albinos are known at a number of loci in mice and other mammals. They are the result of the absence or inhibition of melanocytes in the affected areas, so that no melanin is produced. In general they are associated with pathological pleiotropisms which may lead to anaemia, inner ear defects, megacolon, neurological effects, skeletal defects, microphthalmia, osteopetrosis, spina bifida, sterility and so on. Homologies between these and human loci affecting pigmentation are now being discovered.

Albinism↗
PubMed1981

Hermansky-Pudlak syndrome: albinism with lipofuscin storage.

The Hermansky-Pudlak Syndrome, a "tyrosinase positive' form of oculocutaneous albinism, is a triad comprising albinism, a hemorrhagic diathesis and ceroid-lipofuscin storage. A pedigree is presented showing consanguinity with a pattern of pseudodominance. Electroretinography in two isolated Hermansky-Pudlak subjects was distinctly abnormal, showing decreased rod and cone responses (as well as abnormal flicker fusion responses) in one patient, and reduced photopic and scotopic responses in another. The decreased ERG responses are discussed with reference to the known retinal abnormalities in both generalized oculocutaneous albinism and Batten's disease, another ceroid-lipofuscin storage disorder.

Adolescent↗
PubMed2000

Partial albinism in a semi-isolated population of great reed warblers.

Albinism in birds is thought to result from the expression of recessive alleles that disrupt melanin pigmentation at feather development. We have studied great reed warblers Acrocephalus arundinaceus in a recently founded and increasing population in Sweden during 15 years for the presence of birds with albinistic feathers. The study population was founded in 1978 and the few cases of albinism was exclusively recorded during the first five years of our study (1985-1989). This fits to the expected pattern if albinism is governed by recessive alleles; we have previously demonstrated that the population suffered from inbreeding during the first years of our study. The albinistic birds experienced a similar lifetime reproductive success as normally coloured birds.

Animals↗
PubMed1989

Bunegin-Albin catheter improves air retrieval and resuscitation from lethal venous air embolism in upright dogs.

Three types of catheters, the Arrow multi-orifice catheter, the American Edwards 7 Fr Swan-Ganz catheter and the Cook Bunegin-Albin multi-orifice CVP catheter were evaluated for their ability to retrieve venous air emboli and effect on the success rate of resuscitation from venous air emboli. The catheters were inserted in dogs anesthetized with isoflurane (1.7%, inspired) and N2O (66%) in O2 and placed in the sitting position with the head 90 degrees to the horizontal. Swan-Ganz catheters were positioned with the right atrial (RA) port just above the junction of the superior vena cava (SVC) and the RA and the pulmonary artery (PA) port in the pulmonary artery. The Arrow and Bunegin-Albin multi-orifice catheters were placed with the proximal orifice just above the SVC-RA junction and the distal orifice near the mid-RA. Dogs were then given a predetermined lethal dose of air (5 ml.kg-1) over 30 sec via the jugular vein. Attempts to aspirate venous air emboli were begun with the first decrease in expired CO2. Both RA and PA ports of the Swan-Ganz catheter were used for aspiration. The amounts of gas retrieved expressed as a percent of the injected air and the incidence of successful resuscitation were compared. Significantly greater percentages of injected venous air were retrieved with the Bunegin-Albin catheter (63 +/- 14%, mean +/- SEM) than with the Arrow multi-orifice catheter (6 +/- 2%) or the Swan-Ganz catheter (14 +/- 5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Evoked potential analysis of visual pathways in human albinism.

PURPOSE: To explore the abnormal crossing of the retinogeniculate pathways in human albinos with visual-evoked potentials (VEPs). METHODS: The authors studied the symmetry of the topographic distribution of pattern onset/offset VEPs over the posterior part of the scalp elicited by monocular stimulation of each eye in 31 consecutive patients with different types of albinism. RESULTS: Twenty-one patients had asymmetric responses, with the major amplitude recorded over the lateral part of the scalp contralaterally to the stimulated eye in 14 patients and ipsilaterally in 7 patients. In two patients, the responses had a symmetric topographic distribution. In eight patients, the amplitude was so low that studying the symmetry was not possible. CONCLUSIONS: These findings demonstrate a non-uniform pattern of asymmetry as a result of the miswiring of the visual pathways in human albinism. Moreover, the low amplitude of the VEP recorded in a consecutive series of patients shows the difficulty of the study of this phenomenon in a clinical setting.

Adolescent↗
PubMedDate not supplied

Oculocutaneous albinism: variable expressivity of nystagmus in a sibship.

Traditionally, the diagnosis of ocular or oculocutaneous albinism (OCA) is based on a constellation of features including the presence of nystagmus associated with iris transillumination defects, hypopigmentation of the fundus, and hypoplasia of the fovea and optic nerve head. Nystagmus is the most frequent ocular sign for the ascertainment of albinism particularly in individuals who have lightly-pigmented parents. We report two siblings, a male and female, with minimal, if any, pigmentation of skin and hair, iris transillumination defects, blond fundi, and hypoplasia of the foveae and optic nerve heads who were discordant for nystagmus; the diagnosis of OCA was based on the clinical findings. These siblings presumably have the same genetic hypopigmentation defect and demonstrate that nystagmus is not a consistent finding in OCA and may not be an absolute criterion for diagnosis.

Albinism↗
PubMed1998

Mutations of the human P gene associated with Type II oculocutaneous albinism (OCA2). Mutations in brief no. 205. Online.

Mutations in the human P gene lead to oculocutaneous albinism type 2 (OCA2, MIM #203200), the most common type of albinism in humans. The P gene encodes a 110 kDa protein that is associated with melonosomal membranes and contains 12 potential membrane spanning domains. The specific function of the P protein is currently unknown. We report 7 new mutations in the P gene associated with OCA2. This includes 6 missense mutations (S86R, C112F, A368V, T592I, A724P and A787V) and one frameshift mutation (1047del7). We also report 8 polymorphisms including one amino acid substitution, D/A257. We and others have found many polymorphisms of the P gene in the coding region, several of which result in amino acid substitutions, making molecular diagnosis problematic. In contrast to this is the tyrosinase gene associated with OCA1, with a limited number of polymorphic variations in the coding region. There is also no apparent clustering of P gene missense mutations in contrast to the clustering observed by the tyrosinase gene missense mutations that define functional domains of the protein. Further mutational analysis is needed to help define the critical functional domains of the P protein and to allow a definitive diagnosis of OCA2.

Albinism, Oculocutaneous↗
PubMed2002

Sister and brother with Vici syndrome: agenesis of the corpus callosum, albinism, and recurrent infections.

A sister and brother with Vici syndrome are described. They both had oculocutaneous albinism, agenesis of the corpus callosum, cataracts, and cardiomyopathy. They were born to healthy unrelated parents, and had postnatal growth retardation, profound developmental delay, hypotonia, and cataracts. The sister had recurrent infections, and died of progressive heart failure at age 19 months. The brother is alive at age six months with mild cardiomyopathy, and had a single episode of acute bronchitis at age three months. Review of the clinical manifestations of the sibs we described and six children reported in the literature indicates that Vici syndrome is a distinct clinical entity. Its main clinical manifestations include growth retardation, profound developmental delay, hypotonia, albinism, agenesis of the corpus callosum, cataracts, cardiomyopathy, and recurrent infections. The occurrence of the syndrome in three pairs of sibs of both sexes born to unaffected parents supports autosomal recessive inheritance.

Abnormalities, Multiple↗
PubMed1990

Aland Island eye disease (Forsius-Eriksson ocular albinism) and an Xp21 deletion in a patient with Duchenne muscular dystrophy, glycerol kinase deficiency, and congenital adrenal hypoplasia.

Glycerol kinase deficiency (GKD) has been described in isolation and in complex phenotypes including either congenital adrenal hypoplasia, Duchenne muscular dystrophy, or both. Cytogenetic and molecular studies have localized these defects to a deletion involving the X chromosome at band Xp21, consistent with its X-linked recessive pattern of inheritance. Other clinical findings in the complex glycerol kinase deficiency (CGKD) patients are mental retardation, short stature, and hypogonadotropic hypogonadism. We report on a 6-year-old boy who, in addition to the CGKD phenotype described above, had ocular hypopigmentation consistent with Forsius-Eriksson ocular albinism, also known as type 2 ocular albinism or Aland Island eye disease. Cytogenetic analysis shows an interstitial deletion in the short arm of the X-chromosome at Xp21.

Adrenal Insufficiency↗
PubMed1994

Oculocutaneous albinism, immunodeficiency, hematological disorders, and minor anomalies: a new autosomal recessive syndrome?

We report on 2 related children, a boy and a girl, from a large Turkish clan. Their parents are both first cousins and have several common ancestors. Both children have tyrosinase-positive oculocutaneous albinism, recurrent bacterial infections, granulocytopenia, intermittent thrombopenia, and microcephaly, a protruding midface, rough and projecting hair, and mild mental retardation. Chromosomes are normal. Metabolic disorders were excluded. None of 14 well-known types of albinism, including Hermansky-Pudlak syndrome and Chediak-Higashi syndrome, nor any other genetic syndrome, characterizes our patients sufficiently. Thus, this combination of symptoms is considered a new autosomal recessive syndrome.

Abnormalities, Multiple↗
PubMed1995

Autosomal-recessive neural crest syndrome with albinism, black lock, cell migration disorder of the neurocytes of the gut, and deafness: ABCD syndrome.

We report on a macrosomic newborn girl with albinism, a black lock at the right temporo-occipital region, and retinal depigmentation. Bilateral deafness was confirmed by brainstem auditory-evoked potentials. In addition, the infant had a severe defect of intestinal innervation. Biopsy showed aganglionosis of the large intestine, and total absence of neurocytes and nerve fibers in the small intestine, indicating a total lack of sympathetic and parasympathetic innervation. The infant died of intestinal dysfunction at 5 weeks. She was the 14th child of consanguineous Kurdish parents. Four sibs of our patient had the same syndrome and died a few days after birth. The other 9 sibs are well, with an unremarkable phenotype. A syndrome of albinism, black lock, deafness, and a total lack of intestinal neural innervation has not yet been reported. It represents a new neural crest syndrome with autosomal-recessive inheritance.

Albinism↗
PubMed2006

Aberrant splicing in the ocular albinism type 1 gene (OA1/GPR143) is corrected in vitro by morpholino antisense oligonucleotides.

An intronic point mutation was identified in the ocular albinism type 1 (OA1) gene (HUGO symbol, GPR143) in a family with the X-linked form of ocular albinism. Interestingly, the mutation creates a new acceptor splice site in intron 7 of the OA1 gene. In addition to low levels of normally spliced mRNA product of the OA1 gene, the patient samples contained also an aberrantly spliced mRNA with a 165 bp fragment of intron 7 (from position +750 to +914) inserted between exons 7 and 8. The abnormal transcript contained a premature stop codon and was unstable, as revealed by Northern blot analysis. We defined that mutation NC_000023.8:g.25288G>A generated a consensus binding motif for the splicing factor enhancer ASF/SF2, which most likely favored transcription of the aberrant mRNA. Furthermore, it activated a cryptic donor-splice site causing the inclusion between exons 7 and 8 of the 165 bp intronic fragment. Thus, the aberrant splicing is most likely explained by the generation of a de novo splicing enhancer motif. Finally, to rescue OA1 expression in the patient's melanocytes, we designed an antisense morpholino modified oligonucleotide complementary to the mutant sequence. The morpholino oligonucleotide (MO) was able to rescue OA1 expression and restore the OA1 protein level in the patient's melanocytes through skipping of the aberrant inclusion. The use of MO demonstrated that the lack of OA1 was caused by the generation of a new splice site. Furthermore, this technique will lead to new approaches to correct splice site mutations that cause human diseases.

Albinism, Ocular↗
PubMed2001

Mutation analysis of the tyrosinase gene in oculocutaneous albinism.

Type I oculocutaneous albinism (OCA) is an autosomal recessive disorder caused by the reduction or the absence of tyrosinase (TYR) activity in melanocytes of the skin, hair and eyes. Here we report an analysis of 45 patients with OCA. We found five novel mutations in the tyrosinase gene involved in the pathogenesis of oculocutaneous albinism type IA or type IB (OCA-1A/B) in five unrelated patients. Three mutations are missense mutations (G109R, P205T and H256Y) and two are nucleotide deletions (336-337delCA and 678-680delAGG). One patient is homozygous for the previously known V275F mutation but has an extremely mild OCA phenotype and has no eye features typical of OCA. In several patients we discovered only one or even no mutation in the coding sequence of the TYR gene. Thus, this disease may also result from mutations in non coding regions of the gene or in another gene involved in the biosynthesis of melanin. Hum Mutat 17:352, 2001.

Albinism↗
PubMed2004

Detection of 53 novel DNA variations within the tyrosinase gene and accumulation of mutations in 17 patients with albinism.

Oculocutaneous albinism (OCA) in man may be caused by mutations within the tyrosinase gene (TYR) resulting in OCA1. Analysing patients with recessively inherited albinism we found DNA variations in 82 unrelated individuals. 53 out of 78 mutations and polymorphisms revealed by this study are not published previously. The changes include 68 nucleotide substitutions resulting in amino acid changes, stop mutations and polymorphisms as well as four nucleotide insertions and six deletions. Furthermore, we found an accumulation of three to five mutations in 17 patients with OCA1.

Albinism, Oculocutaneous↗
PubMed2006

Rapid genetic analysis of oculocutaneous albinism (OCA1) using denaturing high performance liquid chromatography (DHPLC) system.

OBJECTIVES: To present the prenatal genetic diagnoses and counseling for two cases of oculocutaneous albinism (OCA) type I family by detection of mutations in the OCA1 gene by denaturing high performance liquid chromatography (DHPLC) system and a review of the literature. METHODS: All DNA samples were extracted from peripheral whole blood and amniocentesis-derived cells. Mutation analysis was performed for all five coding exons of the TYR gene, which were amplified by PCR. DHPLC was used for heteroduplex detection and sequence analysis was performed to demonstrate the mutation loci. RESULTS: Case 1: After sampling of blood from the family members and performing amniocentesis of the fetus, it was demonstrated that the affected boy and the female fetus were shown to be compound heterozygotes for mutations in the TYR gene. In addition, it was shown that the parents were carriers of the two mutations. However, the couple chose to keep the baby. Case 2: Mutation analysis of the DNA of the siblings revealed two heterozygous mutations in the TYR gene. Her husband is free of the disease. According to the principles of autosomal recessive inheritance, the incidence of affected offspring is very low. CONCLUSIONS: Herein we introduce a novel application for molecular diagnostic of DHPLC coupled with direct sequencing, which can provide an effective and exact diagnosis in patients with albinism. Clinicians should be cognizant of the risk of OCA inheritance by the offspring through careful identification of genetic mutations and the inheritance mode, both important to ensure comprehensive genetic counseling.

Adult↗
PubMed1993

Prenatal diagnosis of syndromes associating albinism and immune deficiencies (Chediak-Higashi syndrome and variant).

We have successfully undertaken the prenatal diagnosis of two hereditary syndromes associating albinism and immune defects. Because the genes responsible for these diseases have not yet been mapped and the immune abnormalities are too subtle to be diagnosed in utero, the prenatal diagnosis was made using a morphological approach. In the case of Chediak-Higashi syndrome, it was based on light microscopic examination of the hair shaft and on light and electron microscopic study of polymorphonuclear cells. In the syndrome associating immune deficiency and partial albinism, the Griscelli syndrome, only examination of the hair was feasible. The diagnosis was negative in 12 fetuses at risk and positive in four.

Albinism↗