What are two examples of genetic diseases

Disorders, Syndromes & Diseases

Genetic diseases and syndromes

Genetic disorders can cause serious diseases in humans and have a negative effect on our fertility. This can, for example, lead to impairment of the reproductive organs and even to miscarriages. Especially for those couples who have already suffered a few setbacks and are trying to get pregnant with medical help, the combination of reproductive medicine and genetics can contribute to the fulfillment of their desire to have children.

If you take a closer look at the genetic disorders mentioned at the beginning, the specialist literature shows two main causes which various genetic diseases can trigger.

A) Chromosomal aberrations

numerical and / or structural changes in the set of chromosomes

B) gene mutations

Changes in the genetic make-up in a gene, gene segment or in several genes

Syndromes due to Chromosomal aberration (Changes in the set of chromosomes)

  • Klinefelter Syndrome
  • Turner syndrome
  • Down syndrome (trisomy 21)
  • Edwards syndrome (trisomy 18)
  • Patau syndrome (trisomy 13)
  • Wolf-Hirschhorn Syndrome
  • Cat-eye syndrome
  • Williams-Beuren Syndrome
  • Prader-Willi Syndrome
  • Angelman Syndrome
  • Miller-Dieker Syndrome
  • Smith-Magenis Syndrome
  • Di George Syndrome

Diseases caused by Gene mutations (monogenetic or polygenetic disease)

  • Cystic fibrosis (cystic fibrosis)
  • Phenylketonuria
  • Neurofibromatosis
  • Chorea huntington
  • Duchenne muscular dystrophy
  • Hemophilia A.
  • Polycystic Kidney Disease
  • Spinal muscular atrophy
  • Myotonic dystrophy
  • Sickle cell anemia

Chromosomal aberration

A) numerical changes

In genetic diseases due to chromosomal aberrations, a distinction is made between numerical and structural anomalies. These changes in the chromosomes are responsible for around half of all spontaneous miscarriages, for example.
Aneuploidy is a numerical abnormality, i.e. individual chromosomes are also present or missing.

Trisomy 21 (Down syndrome) as an example of aneuploidy: Chromosome 21 usually occurs twice in the human chromosome set. In Down syndrome, however, this chromosome is present three times.

B) structural changes

If the genetic disease is triggered by a structural chromosomal aberration, it can be a deletion, duplication, inversion, insertion or translocation.

With gene mutations, a change in the genetic material takes place in a gene, gene segment or in several genes and leads to so-called monogenetic or polygenetic diseases.

In monogenic diseases, individual genes / gene segments are affected.

There are basically two possibilities with regard to the way in which a genetic disease is transmitted or occurs. Either this disease is already present in the family and is passed on to the offspring according to a certain principle (AD, AR, X-linked) (e.g. cystic fibrosis), or it occurs "spontaneously" and is thus a new one (e.g. down Syndrome).

Inheritance of monogenic diseases

This representation of the inheritance of monogenic diseases illustrates the risk of transmission of severe hereditary diseases to the offspring, caused by the mutation of a single gene.

AD = autosomal dominant inheritance | AR = autosomal recessive inheritance | X-linked = X-linked recessive inheritance
Graphic | Source: "Recent Advances in the Field of Preimplantation Genetic Analysis" M. Hruba, OEGRM Annual Meeting 2016
autosomal dominant inheritance
autosomal recessive inheritance
X-linked recessive inheritance