Sex-linked signs and diseases. chromosomes autosomal (non-sexual) sexual xx and xy sex of the offspring is determined by the type of sperm (male gamete) - presentation

Examples of diseases

1) Phenylketonuria 2) Marfan syndrome 3) Ichthyosis (not sex-linked) 4) Progeria 5) Arachnodactyly

Phenylketonuria

Phenylketonuria is a disease of amino acid metabolism. Described in 1934 by A. Fehling. The pathology is associated with a deficiency of the liver enzyme, phenylalanine hydroxlase, which impairs the conversion of phenylalanine to tyrosine. Signs: increased excitability and muscle tone, tremor, mental retardation.

Marfan syndrome

Hereditary disease connective tissue, manifested by skeletal changes: tall stature with a relatively short body, long spider-like fingers, loose joints, often scoliosis, kyphosis, deformities chest, arched sky. Eye lesions are also common.

Ichthyosis

Ichthyosis is a hereditary dermatosis characterized by a diffuse disorder of keratinization, such as hyperkeratosis, manifested by the formation of fish-like scales on the skin.

Progeria

Progeria is a very rare genetic defect. In this case, changes in internal organs and skin appear. The reason for this is the aging of the body, which occurs prematurely. The classification includes childhood and adult progeria. There are no more than eighty cases of this disease in the world.

This rare disease manifests itself in rapid aging, which begins in childhood.

Arachnodactyly

High release of adrenaline, characteristic of the disease,

contributes not only to the development of cardiovascular complications, but also to the emergence in some individuals of special fortitude and mental talent.

• Genetics of sex. Sex-linked inheritance.
• Genetics of sex. Sex-linked inheritance.
• Genetics of sex. Sex-linked inheritance.
• Genetics of sex. Sex-linked inheritance.

“We all stand on the shoulders of our ancestors”

Biology teacher MBOU "Levkovskaya Secondary School No. 7

Chernakova Nina Evgenievna

… all happy families are alike, but every unhappy family is unhappy in its own way

L.N. Tolstoy

• Map of human chromosome set

The human karyotype contains 22 pairs of chromosomes, identical in males and females. female body, and one pair of chromosomes that distinguishes both sexes. Chromosomes that are the same in both sexes are called autosomes. The chromosomes by which male and female sexes differ from each other are sex or heterochromosomes. The sex chromosomes in women are the same, they are called X chromosomes. Men have an X chromosome and one Y chromosome.

Customer:

Sex ratio

In humans, most vertebrates, many

In insects and dioecious plants, the homogametic sex is the female sex (XX), and the heterogametic sex is the male sex (XY).

In birds, butterflies, reptiles, and tailed amphibians, the homogametic sex is the male sex (XX), and the heterogametic sex is the female sex (XY). The sex chromosomes in these species are sometimes designated by the letters W and Z, with males designated by the symbols ZZ and females by WZ.

In Orthoptera (grasshoppers) homogametic

The sex is female (XX), and the monogametic sex is male (XO).

Haploidy is widespread in bees and ants. These organisms do not have sex chromosomes: females are diploid and males are haploid.

In some animals, sex determination depends on external conditions. For example, in the sea worm Bonelia, individuals that remain free-swimming in the larval stage become females, and larvae attached to the body of an adult female become males as a result of the muscularizing effect of a hormone secreted by the female.

Traits inherited with sex chromosomes X and U, got the name interlocked with the floor

Inheritance of diseases linked to X- chromosome

* classic hemophilia

*absence of gonads

*color blindness (color blindness)

*hypoplasia (darkening of teeth)

*hydrocephalus

• Inheritance linked to - chromosome

* hypertrichosis

*webbed

• Detailed map Human X chromosomes

More than 370 diseases associated with

X chromosome.

Since males have one X chromosome, all genes localized on it, even recessive ones, immediately manifest themselves in the phenotype .

• Clinical signs:
• sub- and intradermal bleeding, hemorrhages in large joints, subcutaneous and intermuscular hematomas, hematuria, severe bleeding from injuries. Cause: deficiency of antihemophilic globulin.
• Inheritance type: X - recessive
• Population frequency– 1: 2500 (boys)

Inheritance of hemophilia

X X

X Y

Female carrier

Healthy man

X Y

X Y

X X

Healthy daughter

Bearer daughter

Healthy son

Sick son

Pedigree of descendants Queen of England Victoria. It is believed that the hemophilia gene arose as a result of a mutation in Queen Victoria herself or in one of her parents .

Pattern of inheritance of hemophilia

Mother is a carrier of the hemophilia gene ( XHXh ), father is healthy (KhNU).

Females heterozygous for any of the sex-linked traits are phenotypically normal, but half of their gametes carry a recessive gene. Despite the father having a normal gene, sons of carrier mothers have a 50% chance of developing hemophilia.

• In people's minds, any mention of hemophilia is primarily associated with the image of Tsarevich Alexei - the son of the last Russian Emperor Nicholas II.
• Alexey was sick with hemophilia, having received it from his mother, Empress Alexandra Feodorovna, who inherited the disease from her mother Princess Alice, who in turn received it from her mother, Queen Victoria

Hemophilia.

a hereditary disease characterized by a lifelong disorder of the blood clotting mechanism. In 80% of cases this is due to the absence or insufficiency of antihemophilic globulin in the blood plasma. As a result, blood clotting time is prolonged and patients suffer from severe bleeding even after minimal trauma.

Inheritance of hemophilia in the family of Tsar Nikolai Alexandrovich

Nicholas II

Alexandra

Anastasia

• Sex-linked inheritance
• Sex-linked inheritance
• Sex-linked inheritance
• Sex-linked inheritance

Color blindness, partial color blindness, is a type of color vision disorder. This disease was first described in 1794. Color blindness occurs in 8% of men and 0.5% of women.

When one of these elements is lost, partial color blindness occurs - dichromasia.

Using these tables, color perception can be impaired. In table No. 1, people with normal vision see the number 16.

People with acquired visual impairment have difficulty or do not distinguish the number 96 in Table No. 2 at all.

• In humans, the gene for color blindness is recessive and is located on the X chromosome. In what case can a colorblind man have a colorblind son?

Solution

M.colorblind

D. colorblind

• Clinical signs: increase in head volume, expansion of the ventricles of the brain; thinning and divergence of the skull bones, disproportion of the brain and facial parts of the skull, strabismus, mental retardation and developmental delay, movement and coordination disorders, nystagmus, atrophy of the white matter of the brain.
• Inheritance type: X-recessive.
• Population frequency – 1: 2000

PEDIGREE WITH X-LINKED TYPE OF INHERITANCE

• 1. Only boys on their mother’s side are affected.
• 2. The proband’s parents are healthy.
• 3. The sick man does not transmit the disease, but all his daughters are carriers.
• In a marriage of a carrier woman with a sick man, 50% of daughters and 50% of sons are sick.

Traits linked to the y chromosome

at -the chromosome is called genetically inert or genetically empty, since it contains very few genes.

In humans, the Y chromosome contains a number of genes that regulate spermatogenesis, the manifestation of histocompatibility antigens, affecting the size of teeth, etc.

Anomalies associated with Y -chromosome, which are passed on from the father to all sons (scaly skin, webbed fingers, heavy hair growth on the ears).

• Clinical signs: Excessive hair growth on all parts of the body except the palms and soles. Since the Middle Ages, only 50 cases of congenital hypertyrchiosis have been recorded. There are no other developmental abnormalities. Local hypertrichosis can occur with metabolic disorders.
• Type of inheritance: AD. Population frequency unknown.

• Hypertrichosis is inherited as a trait linked to the y chromosome.

What is the probability of having children with this anomaly in a family where the father has hypertrichosis?

Functional disorders

Action

gametes

alcohol

Slowing embryo growth

nicotine

mutations

Inhibits the development of nerve cells

Narcotic substances

radiation

x-ray

radioactive

ultraviolet

Sun, ultrasound, fluorography, x-ray examination, computer, cell phone, household appliances (microwave, TV)

cell

mutation

Damaged DNA

• Phenylketonuria(PKU) is a congenital disease caused by a violation of the transition of phenylalanine to tyrosine and leading to mental retardation.
• Clinical picture Neurological and mental disorders Mental retardation Increased excitability in childhood Specific gait Specific posture and sitting position Unusual position of the limbs Stereotypical movements Increased tendon reflexes Seizures Skin changes Dryness Eczema Vomiting in the newborn period Specific mouse body odor.

• 47 chromosomes – extra X chromosome – XX Y
• Seen in young men
• High growth
• Violation of body proportions (long limbs, narrow chest)
• Developmental delay
• Infertility

• Shereshevsky-Turner syndrome (45; X0) is observed in women. It manifests itself in delayed puberty, underdevelopment of the gonads, and infertility.
• Women with Shereshevsky-Turner syndrome are short, their body is disproportionate - the upper body is more developed, the shoulders are wide, the pelvis is narrow - lower limbs shortened, short neck with folds, “Mongoloid” eye shape and a number of other features.

• Down syndrome occurs when the baby's cells have not 46, but 47 chromosomes. Such children are mentally retarded, 50% have heart defects, a weak immune system... In a newborn, the disease can be diagnosed based on the characteristic appearance child: a rounded skull, a slanted back of the head, an oblique eye shape, a wide bridge of the nose, an additional eyelid, light gray spots on the iris, a “Gothic” palate, small ears. The mouth is usually half open; the tongue is thick, often protrudes from the mouth, covered with transverse grooves; the hand is wide, the fingers and toes are shortened, the little finger is often curved; sometimes the fingers are fused (partial or complete syndactyly). The palm often shows a complete transverse fold (monkey fold).

• Remember! The health of your future children is in your hands!
• Remember!
• The health of your future children is in your hands!

You have a choice:

stay healthy and live without problems or...

• You have a choice: stay healthy and live without problems or...

Remember that the health of your future children depends on your health.

• In humans, pseudohypertrophic muscular dystrophy ends in death at 10–20 years of age. In some families, the disease is influenced by a sex-linked recessive gene. The disease has been reported only in boys. If affected boys die before childbearing, why does this disease not disappear from the population?

Smirnova Z. M.

Genetics of sex

• Chromosome complex of a woman 44 autosomes + XX heterochromosomes.
• For a man - 44A + XY = 46.
• Sex is determined at the time of fertilization and depends on the combination of sex chromosomes in the gamete. Since gametes with X- and Y-chromosomes are formed in men during meiosis in equal quantities, the sex ratio is 1:1

• A sex whose individuals have identical sex chromosomes and form 1 type of gametes is called homogametic; a sex whose individuals have different sex chromosomes and form 2 types of gametes is called heterogametic.

P XX x XY

G X X Y

F1 XX XY

Homogametic sex Heterogametic sex

Sex chromosomes determine the development of primary and secondary sexual characteristics

Primary sexual characteristics - gonads and organs, take a direct part in the processes of reproduction (gametogenesis, insemination, fertilization).

Secondary sexual characteristics are not directly involved in reproduction. Develop under the influence of sex hormones

(in a person aged 11-15 years). These are features of the skeleton, subcutaneous fat, hair, timbre of voice, and behavior.

Sex-linked inheritance

• Sex chromosomes have homologous regions (inheritance

the genes contained in them do not differ from the autosomal one).

• But there are also non-homologous regions in the X chromosome and Y chromosome.

X-linked traits are caused by genes located in a non-homologous region of the X chromosome

(color blindness, hemophilia, etc.).

Holandric characteristics are caused by genes located in a non-homologous region of the Y chromosome (ichthyosis, hairiness of the middle phalanges of the fingers, etc.).

A region that does not have a homolog on the Y chromosome

A region that does not have a homologue on the X chromosome

Homologous regions of sex chromosomes

Sex-linked inheritance

• Sex chromosomes, in addition to genes that determine sex, contain genes

not related to gender. The signs they define are called gender-linked characteristics.

• If a gene is linked to the X chromosome and is recessive - X h (hemophilia, color blindness), then in women it can only manifest itself in

homozygous state (X h X h ).

• Men do not have a second X chromosome, and there is no homologous chromosome in the Y chromosome. section of the X chromosome, so in men these genes always appear and are dominant for them (X h Y).

• The phenomenon when a gene (hemophilia, color blindness in men) is present in an individual not in

form of a pair of alleles, and in singular called hemizygous condition.

• Males are hemizygous for genes located in

X chromosome. Therefore, recessive hereditary diseases caused by genes such as hemophilia, color blindness, more often found in men.

Sex-linked inheritance

• If the gene is located on the X chromosome (gene for hemophilia, color blindness, etc.).

It can only be passed on from father to daughters.

• From the mother it is distributed equally among daughters and sons.

X H X h

x X H Y

X H

X H

X h

F 1

X h Y

X H Y

X H X H ;

X h X H ;

X h Y

X H X h

X H Y;

X H X H

X-linked recessive gene

Dominant gene (normal)

Dominant gene (normal)

Sick

Healthy

Carriers

X h X H ;

X h X H ;

X H Y;

X H Y ;

X h X H ;

X h Y

X H Y;

X H X H

Hemophilia

X H X h

X H X h x X H Y

X H

X h

X H

X H X H ; X H Y; X h X H ; X h Y

Sex-linked traits

Normal color perception

color blindness

X d X d

color blindness

X D Y – norm

X d Y

X D X d

or normal

X D X D

Sex-linked traits

If the gene is linked to the Y chromosome (hairy ears, webbing between toes), then it can only be passed on from father to sons, because A sperm with a Y chromosome, fertilizing an egg with an X sex chromosome, determines the development of the embryo according to the male type.

XX x XY Z

Y Z

It has 23 pairs of chromosomes, of which 22 pairs are autosomal, and the 23rd is sexual. In women, the 23rd pair is XX, in men - XY. The Y chromosome plays a decisive role in determining sex. Human WomanMan Has only X chromosomes (one from the mother, the other from the father) Carries only X chromosomes Has an X chromosome from the mother and a Y -chromosome from father Can carry both X chromosomes and Y chromosomes X XY

SEX-LINKED TRAITS Sex-linked inheritance is the transmission of genes located on the sex chromosomes and the inheritance of traits controlled by these genes. Sex-linked traits are non-sexual characteristics whose genes are located on the sex chromosomes. There are usually more of them in the X-chromosomes. chromosome

HERITABLE SEX-LINKED DISEASES Gene diseases and abnormalities Chromosomal diseases Depend on the sex chromosomes of the parent organisms. Disorders of genetic processes Do not depend on parents, occur due to disturbances in the divergence of chromosomes