Will genetic disorders caused by more or fewer chromosomes continue to be inherited?

Chromosomal abnormalities are most likely to have offspring on XYY-type chromosomes. This is a normal childbearing, and the offspring are also likely to have abnormalities.

Human chromosomes are divided into autosomes (22 pairs) and sex chromosomes (x,y for males x, x for females 1 pair).

If the sex chromosome abnormality causes the fertility abnormality, it cannot be inherited, and if it is possible, it can be inherited.

For example, sex chromosomes mutate into x,x,y

After he marries a normal woman (x, x), the chromosomes of the children can be of three types: (x, x, x x, x, y, y).

If the child is an autosomal abnormality, such as trisomy 21, the child has a 50% chance of being normal, which means that half of the children are abnormal.

If the fertilized gametes are also less or more chromosomal, they are inherited.

Trisomy 21 syndrome, which is more commonly known to the world, has an extra chromosome 21, and the common manifestations are abnormal appearance and mental retardation.

In the case of humans, there are 23 pairs of chromosomes, of which 22 are autosomes (1 22) and one pair of sex chromosomes (x and y). Chromosomes carry genetic information – genes that determine biological traits.

Inherited genes are divided into dominant genes and recessive genes. When dominant genes are present, dominant genes work, recessive genes do not. It only works if two recessive genes are present.

For example, suppose A is the dominant gene and A is the recessive gene.

Then: If the first generation of fathers exhibits a certain trait, the genotype is AA. The maternal genotype can be AA or AA.

In the second generation (offspring), the son genotype may be AA, and the shape determined by the recessive gene A will not be exhibited. The genotype of the spouse is AA or AA.

In the third generation (grandchildren), the grandchildren may have an AA genotype, and in this case, they will show the traits of the first generation, that is, their grandfather.

However, the hereditary traits of organisms are extremely complex issues, not only related to the theories of genetics, quantitative genetics, epigenetics and other related disciplines, but also directly and indirectly related to other disciplines and environmental factors.

Autosomal recessive disorder The causative gene is on the autosomal body, and the genetic trait is recessive, that is, the disease is only shown when it is homozygous. Both parents are carriers of the disease-causing gene, so it is more common in the children of consanguineous marriages. (The carrier is not sick, the patient is in the next generation).

Inherited disease genes are on the autosome, and only when the genetic trait is recessive, that is, homozygous, the disease is displayed. To put it simply, the carrier is not sick, and the patient is in the next generation.

d.Monogenic disorders are disorders that are controlled by one gene.

This option is wrong, monogenic disorders are disorders that are controlled by paired alleles on homologous chromosomes rather than having one gene.

1. First of all, it is judged whether it is Y chromosome inheritance, and the characteristics are: the son will get the father, the father will get the son, and the male will not pass on the female;

2. According to the formula: there is a hidden nature of the disease (the parents are not sick, and the children are sick) and the middle generation is not the dominant (the parents are sick, and the children are not sick) to judge the explicit and hidden nature of the disease;

3. If it is judged to be a recessive disease: if there is no middle-born female disease, it must be an autosomal recessive disease; If all the fathers and sons of the female patient are affected, it is likely that the disease is recessive on the X chromosome. If there are no female patients, all male patients should be judged according to the additional conditions in the question, but it is more likely to be an X-chromosome recessive disease, because there are more male patients than female patients with this disease;

4. If it is judged to be a dominant disease: if there is a middle-aged girl without disease, it must be an autosomal dominant disease; If all mothers and daughters of a male patient are affected, it is likely to have an X-dominant disease. If there are no male patients, but only female patients, it will be judged according to the additional conditions in the question.

5. If it is not possible to judge the obvious explicit and recessive relationship (there is no out of nothing or there is nothing in the question), it can only be judged by the additional conditions in the question, such as: the question tells that the disease is inherited with sex, or someone is homozygous, or a man does not carry the pathogenic gene, etc. Some topics can be hypothesized if what type of disease is .........

In addition, if there is no special explanation in the title, if it can be judged as X explicit (recessive) STD, it can never be ruled out as a common explicit (recessive) STD.

Companion inheritance is divided into: 1. Companion x dominant; 2. With x recessive; 3. Y genetics.

How to determine the use of elimination, if none of the above three conditions are met, it is autosomal inheritance.

1. With x dominant: father and daughter will be sick. 2. With x recessive: the mother and the child will be sick. 3. With Y genetics: all the affected patients are male.

Companion X inheritance also has the characteristics of intergenerational inheritance and cross-inheritance.

The male parent of the dominant trait and the female parent of the recessive trait were crossed, and the phenotypic ratio of male and female offspring was the same. It is autosomal inheritance, and if the offspring do not have a male and female phenotype ratio, it is sex chromosome inheritance.

Fathers and daughters will suffer, mothers and children will suffer, and children and grandchildren will be endless (both men will suffer) as companion inheritance.

Others are generally autosomal and cytoplasmic (related to motherhood).

According to Mendel's laws of inheritance, if it is a recessive trait, one of the parents has a sick AA and the other has a normal AA, then the offspring is AA and will not show the recessive trait. And if it is a dominant genetic disease, one of the parents has a sick AA and a normal AA, that is half of the parents may be normal AA and half may be diseased, or one of the parents is sick AA and one is normal AA, then all of them are diseased, you think about it, the recessive needs two A to appear, but the dominant only need at least one A is fine, and the probability of disease is much more dominant if it is dominant!

In the cells of dioecious organisms, there are two types of chromosomes, namely autosomes and sex chromosomes, and no matter what type of chromosomes they are, there are many genes distributed on them. This article takes the human body as an example to focus on the distribution and inheritance of genes on sex chromosomes.

The sex determination of human beings belongs to the XY type, and in their somatic cells, the size and morphology of the XY pair of sex chromosomes are different. The X chromosome is slightly larger, the Y chromosome is slightly smaller, and their different segments (see the four segments A, B, C, and D in the figure show) are distributed with different genes, and the inheritance of genes in each segment is different, which is summarized as follows

Genes on the A segment of chromosome 1 X, alleles or identical genes can be found on the D segment of the Y chromosome. In fact, this segment is the cognate segment of x and y. Genes located in this segment are inherited as genes on a pair of homologous chromosomes in autosomes.

If a pair of genes is involved, the inheritance follows the law of gene segregation; If two or more pairs of genes are involved, the inheritance follows the law of linkage and interchange of genes. The inheritance of genes in this segment is not significantly related to the sex of the organism.

2 The gene on the C segment of the Y chromosome does not find a corresponding allele or the same gene on the X chromosome, which belongs to the non-homologous segment of the Y chromosome. Genes in this segment, whether dominant or recessive, can only be passed on to males with the Y chromosome, and traits controlled by this gene are only manifested in males. This is inherited on the Y chromosome.

3 X chromosome B segment on the gene in Y

No corresponding allele or the same gene can be found on the chromosome, and the segment belongs to the non-homologous segment of the X chromosome. The human color blindness gene and hemophilia gene are located in the non-homologous segment of the X chromosome. There are two scenarios regarding the inheritance of genes on this segment:

1) If the gene on this segment is recessively pathogenic and has the same genetic characteristics as color blindness and hemophilia, that is, there are more male patients than females, and it is cross-inherited (the father passes the disease-causing gene from daughter to grandson).(2) If the gene on this segment is a dominant pathogenic gene, then there are 3 genotypes in females, xbxb

diseased), xbxb (diseased), xbxb (normal); There are 2 genotypes in males, XBY (diseased) and XBY (normal).It is not difficult to see that males only need one XB to behave normally, while females only have two XBs at the same time, so the heredity in this case tends to be more female than male. In addition, according to the law of parent-child inheritance, the father is sick.

xby), the daughter must be sick; If the son is sick (XBY), the causative gene must have come from the mother, which is obviously consistent with the characteristics of cross-inheritance.

In summary, there are gene distributions on sex chromosomes X and Y, and the inheritance of genes in sections A and D has no obvious relationship with sex, and the inheritance of genes in sections B and C is closely related to sex!

In autosomal recessive disorders, both parents are heterozygous, and the probability of developing the disease in children is 25%.One of the parents is heterozygous, and the probability of the disease in the child is zero, but 100% carrier. One parent is heterozygous and the other is homozygous, with 5% of children affected and 50% carriers. If both partners are homozygous, 100% of the children are affected.

In the case of associated X-linked recessive disorders, if the mother is a carrier and the father is normal, the probability of developing the disease in the offspring is 50%.50% of the daughters are carriers. If the father is patient and the mother is normal, the daughters are carriers and the sons are normal. If the father is a patient and the mother is a carrier, 50% of the offspring are daughters and 50% are carriers; Of the sons, 50% were patients and 50% were normal.

In general, the recurrence rate of chromosomal disorders in offspring is the same as that of the general population, but in a small number of chromosomal disorders, due to the abnormality of the parents themselves in terms of chromosomal disorders, it is estimated according to the chromosomal condition of the parents.

According to the incidence and heritability of polygenic genetic diseases in the population, the probability of the occurrence of the above offspring is in terms of "overall", for example, the incidence of a hereditary disease in the offspring is 25%, and the first child is already a child, but it does not mean that the birth of the second child can be guaranteed to be normal, but only that there is still 25% in the second child, which is a possible disease.

Regardless of what kind of hereditary disease, in the marriage of close relatives, the chance of their children suffering from hereditary diseases is hundreds of times higher than that of the normal ordinary population, so the marriage law stipulates that the marriage of immediate family members and relatives within three generations is prohibited, which is an important criterion to ensure the eugenics of offspring, and reduces the incidence of genetic diseases in offspring.

4 Congenital and genetic diseases

As the name suggests, congenital diseases are those who are born with a disease. It causes both certain genetic diseases and certain viral infections that occur during pregnancy.

Genetic diseases refer to the occurrence of these diseases that require one or more inherited genes and pass them on to offspring in a certain way. Obviously, congenital diseases involve both environmental factors and genetic factors, whereas heredity involves only genetic factors. The two are both related and distinct.

The relationship between the two is divided into several situations:

(1) It is a congenital and hereditary disease.

It is a congenital, but non-hereditary disorder。The disease is caused by environmental factors or changes in maternal conditions, such as radiation, hypoxia, or viral infections, such as congenital cataracts.

This needs to prevent consanguineous marriage, and his infectious chromosome heritability rate is about 50% is very high, which means that one of the two people may have some autosomal inherited diseases. So it is very wise for China to prevent consanguineous marriages.

The inheritance of chromosomes is about 80% hereditary, because this chromosome will slowly enter the body through the fertilized egg, in which case the gender gap will be formed.

This can't be avoided, the heritability is about 30% 50%, chromosomal inheritance is inherent, there is no way to avoid it,

Polygenic genetic diseases are inherited diseases controlled by multiple pairs of alleles, such as progressive muscular dystrophy and so on;

Chromosomal abnormalities are genetic disorders caused by variations in chromosomal structure or quantity, such as trisomy 21, Turner's syndrome, and many more.

Polygenic genetic diseases are diseases caused by changes in more than one pair of genes, and all of them have a high dominant incidence.

Chromosomal genetic disorders are genetic diseases caused by chromosomal aberrations, and the mechanism of occurrence is changes in the number and structure of chromosomes.