On February 20, the news reported that "the world's first golden penguin was found in Antarctica", which experts said should be caused by albinism. In fact, not only penguins will appear albinism, but humans will also appear.
So what exactly is albinism?
Is it really all white? So let's take a look at albinism.
<h1 class="pgc-h-arrow-right" >What is albinism? </h1>
Albinism is a genetic disorder whose main clinical manifestation is pigment deficiency in various parts of the body. Albinism is divided into 3 types: ocular dermatoa (OCA affected by both the skin and eyes), ocular albinism (OA) and albinism-related syndromes (manifestations of systemic albinism with other systemic abnormalities).
is albinism common < h1 class="pgc-h-arrow-right" >? </h1>
Albinism is a rare disease, and the epidemiological data of albinism are mostly from Western populations (mainly In North America and Europe), and the overall incidence is about 1:17 000 (1:10 000 to 20 000). The incidence in some countries in Africa can be as high as 1:1400, which may be due to the inbreeding and founder effects. The overall incidence of albinism in Chinese group was 1:18 000
<h1 class="pgc-h-arrow-right" > how to identify albinism? </h1>
OCA is divided into 7 types. Patients have clinical manifestations at birth, due to the lack of skin pigmentation throughout the body, the skin capillaries are exposed, the skin is thin and soft, white and red, and accompanied by varying degrees of vasodilation. Patients are highly sensitive to ultraviolet rays and often develop diseases such as solar dermatitis, actinic cheilitis, basal cell carcinoma, and squamous cell carcinoma. The hair is pure white, silvery white, yellow, gold or brown. Eyelashes and eyebrows are white or yellowish. The color of the retina and iris is reduced, and the color of the pupil is reduced. Lightphobia is pronounced during the day and night vision is normal, but can also be accompanied by other visual changes such as decreased visual acuity, retinal fovea dysplasia, altered optic cross nerve pathways, and nystagmus.
<h1 class="pgc-h-arrow-right" > suspected albinism, what should I do? </h1>
If you experience those symptoms, see a doctor right away
Suppose that when a pregnant woman who has given birth to a child with albinism becomes pregnant again, through genetic counseling and prenatal diagnosis, prenatal diagnosis mainly includes the following methods.
(1) Diagnosis by biopsy of fetal scalp or skin hair follicles: observe whether there are mature melanocytes in melanocytes.
(2) Direct observation and diagnosis through fetal microscope: the method is to apply the fetal mirror into the amniotic cavity at the deepest part of the amniotic pool under the guidance of B ultrasound at 19 to 27 weeks of pregnancy, observe the color of fetal hair, and carry out prenatal diagnosis of albinism.
(3) Prenatal genetic diagnosis: first identify the genetic mutations in the family line, and then extract the fetal genomic DNA by villus puncture at 10 to 12 weeks of pregnancy, so as to achieve the purpose of prenatal diagnosis.
Genetic testing can also be done, and the molecular diagnosis process of albinism optimized for the characteristics of the Chinese population is as follows
() First, according to the clinical manifestations and the frequency and hotspot of mutations in the population, the genes such as TYROCA2.SLC45A2 are detected by Sanger sequencing and the mutation hotspot area is preferred.
(2) Those with negative or larger disease-causing genes (such as CHS1) can be sequenced for next-generation sequencing of genes related to hypopigmentation: including 18 known albinism-causing genes (Table 1) and 82 candidate genes for albinism;
(3) If the result is still negative, or if the patient is a homozygous variant and the parental source is unknown, the deletion of large fragments in the homologous region of the variation should be excluded. Or the patient found only one pathogenic variant. or NGS data indicate the presence of gene copy number variations that can be verified by fluorescence quantitative PCR or MLPA detection 01211;
(4) The above test is still negative. Whole exome or whole genome sequencing is required;
(5) Usually, the results of NGS testing need to be verified by Sanger sequencing to determine whether they are de nouo mutations. A definitive diagnosis is made when 2 trans-causative variants are found, or if the homozygous causative variants are from Liu Xin.
< h1 class= "pgc-h-arrow-right" > you are albinism, will the child be born with albinism? </h1>
If both parents are carriers of the albinism gene, there are 4 possibilities for having a child:
1. Completely normal; 2 and 3. Normal performance, but carrying albinism genes; 4. have albinism. In other words, a couple who each carry albinism genes has a 1 in 4 chance of giving birth to an albinism child.
If an albino patient marries a healthy person, there are 3 possibilities:
Healthy people carry the same albinism genes as each other, and two people will give birth to albinism children;
Healthy people do not carry the same albinism genes as each other, and the two will give birth to normally behaving children, but may carry albinism genes;
Healthy people carry albinism genes, but unlike each other, two people will have children who behave normally, but may carry albinism genes.
what is the prognosis of < h1 class="pgc-h-arrow-right" > albinism? </h1>
Albinism usually does not affect life expectancy, and development, intelligence, and fertility are normal, but light sensitivity can limit outdoor activities. The skin of people with albinism is not tanned, but it is easy to get sunburned.
Related network resources
Li Wei's research group at Beijing Children's Hospital affiliated to Capital Medical University designed a gene-oriented file format for human and mouse albinism-related genes, which collected mutations in different albinism genes and integrated relevant data while using bioinformatics tools for predictive analysis, and developed an HPSD database (http://www.genelab-bch.com.cn/HPSD/) at the University of Minnesota, USA William Oetting's lab has built an Albinism Database (http://www.ifpcs.org/albinism/) that includes known gene mutations and SNPs for some of the albinism. In addition, the European Society of Pigment Cells has established a database of color genes (http:// www.espcr.org/micemut/) that can lead to hypopigmentation or sedimentation, some of which have mutations in mice or other model animals that have been shown to cause albinism and are an important resource for human albinism candidate genes.
bibliography:
1. National Health Commission of the People's Republic of China. Guidelines for the diagnosis and treatment of albinism[A]. Chinese Practical Journal of Rural Doctor 2019 Vol.26 No.9.
2.GranskovK,EkJ,Brondum-Nielsenk,Oculocutaneousalbinism[J]. Orphanet J Rare Dis,2007,2:43.
3.Zuhlke C,Criee C,Gemoll T,etal. Polymorphisms in the genes for oculocutaneous albinism type 1and type 4 in the German population[J]. Pigment Cell Res,2007,20(3):225-227.
4.Rooryck C,Morice-Picard F,Elcioglu NH,etal. Molecular diagnosis of oculocutaneous albinism:new mutations in the OCA1-4 genes and practical aspects[J]. Pigment cell Melanoma Res,2008,21(5):583-587.
5.SpritzRA,Fukai K,Holmes SA,etal. Frequent intragenic deletion of the P gene in tanzanian patients with type II oculocutaneous albinism(OCA2)[J]. Am J Hum Genet,1995,56(6):1320-1323.
6.Cruz-Inigo AE,Ladizinski B,Sethi A.Albinism in Africa:stigma,slaughter and awareness campaigns[J]. Dermatol Clin,2011,29(1):79-87.
7. Gong Yaoqin,Shao Changshun. Genetic Epidemiology of Albinism[J]. Acta Genetica Sinica,1994,21(3):169-172.]
8.Bennett DC. Lamoreux MLThe color loci of mice - a genetic century[1]. PigmentCellRes200316(4):333-344.DOI:10.1034/.1600-0749.2003.00067.x.
9.Li w.He M.Zhou H.et al. Mutational data integration in gene oriented files of the Hermansky-Pudlak SyndromeDatabaseL]. Hum Mutat.2006.27(5):402-107. DOI.10.1002/humu.20309.