Arxiu d'etiquetes: family

Rare diseases: fight against oblivion

We are ending the month of February, and this means that the Rare Disease Day is approaching. Marfan syndrome, Williams syndrome, DiGeorge syndrome, Crohn’s disease, Fanconi anaemia, mucopolysaccharidosis, among many others make up the list of these diseases. Why are they called minority diseases or rare diseases?

WHAT ARE MINORITY DISEASES?

A minority disease is that which affects less than 1 in 2,000 people. Although individually they are rare, there are many diseases of this type (6,000-7,000), so there are many affected patients.

Although the definition of minority disease is what I have just said, in the pharmaceutical industry it is that disease in which it is not profitable to develop a drug due to the low number of patients, the limited information available, the poor diagnosis, the lack of clinical studies and the difficult location of patients. It is for this reason that the families themselves create their own foundations to obtain financing for the investigation of these diseases.

A few years ago these diseases were socially forgotten, but, fortunately, they are now socially transcendental and recognized.

As I said, there are around 7,000 minority diseases described and every year between 150 and 250 new ones are described, thanks to new technologies.

A large number of these diseases affects children, that is, they manifest themselves at an early age. It is necessary to know that most have a genetic basis, caused by mutations in specific genes such as cystic fibrosis or several muscular dystrophies. But there are also related to environmental factors, such as some types of anaemia due to lack of vitamins or due to medications. This is the case of malignant mesothelioma, a breast cancer, in which more than 90% of cases are due to asbestos exposure. However, there are still many without knowing their origin or data on their prevalence.

MINORITY DISEASES IN NUMBERS

The fact that these diseases affect few people and the ignorance of their symptoms by the public and professionals, it is estimated that the time that elapses between the appearances of the first symptoms until diagnosis is 5 years. In 1 of every 5 cases, more than 10 years may pass until the correct diagnosis is obtained. This means not receiving support or treatment or receiving inadequate treatment and worsening the disease.

Not all hospitals have the means to treat those affected, for this reason it is estimated that practically half of sufferers have had to travel and travel in the last 2 years out of their province because of their illness, either in look for a diagnosis or treatment.

Minor diseases represent a significant economic cost. The cost of diagnosis and treatment accounts for around 20% of the annual income of each affected family. This means an average of more than 350€ per family per month, a figure very representative of the high cost involved in the care of rare diseases. The expenses to cover in the majority of cases are related to the acquisition of medicines and other health products, medical treatment, technical aids and orthopaedics, adapted transport, personal assistance and adaptation to housing.

TREATMENT FOR MINORITY DISEASES

Only 1-2% of minority diseases currently have some type of treatment, therefore, much remains to be investigated.

There are 4 basic types of treatment for rare genetic diseases:

PHARMACOLOGICAL THERAPIES

It consists in the modification of a normal or pathological biochemical reaction by an external chemical agent.

The development of a drug is a very expensive process and difficult to quantify. Currently many millions have to be invested for a new drug to reach the patient.

But what is a medication? A medicine is a small organic molecule, which typically has to be:

  • Specific to solve a molecular problem (ex: prevent an abnormal interaction between two proteins)
  • Very active and very tuned for your target
  • Very little toxic
  • Distribute well throughout the body and reach the target tissue
  • Cheap to produce or, at least, that can be synthesized in industrial quantities
  • Stable
  • New (patentable)
  • It has to be commercialized

GENE THERAPY

Attempt to correct defective genes responsible for diseases in the somatic (non-sexual) line, either by:

  • Loss of function: incorporate the normal gene (ex: phenylketonuria)
  • Function gain: eliminate the responsible mutation, eliminating the protein (ex: Huntington)

Limitations:

  • Only the reversible characteristics of a genetic disease can be corrected
  • The size of the DNA to be incorporated in the patient’s genome
  • Immune response against the viral vector (retroviruses, adenoviruses, adenoassociates)
  • Inactivation of an essential gene that can cause a problem greater than the disease
  • Directionally to appropriate target cells

CELLULAR THERAPY

Describes the process of introducing new cells into an affected tissue, with or without previous gene therapy. It is necessary to introduce many cells because the treatment is effective and, sometimes, these cells can go to unwanted tissues or have some types of abnormal growth.

SURGERY

For example in congenital heart defects.

RARE DISEASE DAY

For rare diseases to cease to be, Rare Disease Day is celebrated on the last day of February, with the aim of raising awareness and awareness among the public about rare diseases; as well as showing the impact on patients’ lives and reinforcing their importance as a priority in public health.

It was established in 2008 because, according to the European Organization for Rare Diseases (EURORDIS), the treatment of many rare diseases is insufficient, as well as in social networks to support people with minority diseases and their families. In addition, while there were already many days devoted to people suffering from individual diseases (such as AIDS, cancer, etc.) before there was not a day to represent people suffering from minority diseases. It was chosen on 29th February because it is a “rare” day. But it is celebrated on the last day of February in years that are not leap years.

Then I leave the promotional video for the Rare Disease Day 2015:

Video 1. Rare Disease Day 2015 Official Video (Source: YouTube)

REFERENCES

MireiaRamos-angles2

Classification and phylogeny for beginners

In this blog, we usually use therms related with the classification of living beings and their phylogeny. Due to the difficulty of these therms, in this post we will explain them for those who are introducing to the topic. 

INTRODUCTION

Before introducing in the topic, it is necessary to explain two concepts, which are usually confused: systematics and taxonomy.

Systematics is the science of the classification and reconstruction of phylogeny, it means that is responsible for reconstructing the origin and diversification of a taxon (unit that we want to classify, such as a species, a family or an order).

On the other hand, taxonomy is the study of the principles of scientific classification, the order and the name of organisms.

In other words, while systematics is responsible for creating systems of classification, which are represented by trees, taxonomy establishes the rules and methods to identify, name and classify each species in the different taxonomic categories based on systematics.

ABOUT SPECIES AND BEYOND

We cannot begin to talk about how to classify species without knowing what is a species and other classification levels of organisms.

WHAT IS A SPECIES?

Along history, it has been given several definitions to the concept species with different approaches.

  • Morphological concept of species: a species is a group of organisms with fix and essential features that represent a pattern or archetype. This concept is totally discarded nowadays, despite morphological features are used in guides to identify species.

INFO-BALLENA
Despite all guides use morphological features to identify species, morphological concept of species is not used (Picture: Revista Viva).

  • Biological concept of species: a species is a group of natural populations which reproduce among them and reproductively isolated and have their own niche in nature. So, a species has common ancestry and share traits of gradual variation.  This definition has some problems: it is only applicable in species with sexual reproduction and it is not applicable in extinct species.
  • Evolutionary concept of species: a species is a single lineage of ancestor-descendent populations that maintains its identity in front of other lineages and has its evolutionary tendencies and historical destination. This approach and the biological one are, in fact, complementary because they are talking about different phenomenons.
  • Phylogenetic concept of species: according to this point of view, a species is an irreducible group of organisms, diagnostically distinguishable from other similar groups and inside which there is a parental pattern of ancestry and descendants.  This point of view covers sexual and asexual reproduction.

ensatina_phylogeny
According to the phylogenetic definition of species, A, B and C are different species. In the C group, all of them are the same species with different types (Picture: Sesbe).

BEYOND SPECIES

Species are classified into a hierarchical system based on more taxonomical categories. From the highest to the lowest category, organisms can be classified in: Domain> Kingdom> Phylum> Class> Order> Family> Genus> Species> Subspecies> Variety> Form. 

We are giving an example: imagine dogs.  Dogs, like wolf, are included in the same species: Canis lupus, but dog is the subspecies Canis lupus familiaris. The naming of a species is its genus (Canis) followed by the specific epithet (lupus). The other taxonomical categories of dogs are: Eukarya Domain, Animal Kingdom, Chordata Phylum, Vertebrata Subphylum, Mammalia Class, Carnivora Order and Canidae Family.

DSC02196
Dogs and wolfs are included in the same species, but they are different subspecies (Picture: Marc Arenas Camps).

HOW IS TREE OF LIFE RECONSTRUCTED?

To reconstruct tree of life, it is the relationships between living and extinct species (phylogeny), we use traits. Traits are features of organisms that are used to study the variation inside a species and among them.

To reconstruct the phylogeny, it is used the shared traits among different taxa. We have to distinguish two types of similarity: when similarity of traits is a result of a common lineage is called homology, while when it is not the result of common ancestry is known as homoplasy.

Probably, it will be easier to understand it with an example. The wings of owls and quails are similar because they have the same origin (homology), but the wings of insects, birds and bats, despite they have the same function, they do not have the same origin (homoplasy).

bio_evoluc_convergente
The wings of insects, birds and bats are an homoplasy (Picture: Natureduca).

There are three types of homoplasy:

  • Parallelism: the ancestral condition of a variable trait (plesiomorphic) is present in the common ancestor, but the derived state (apomorphic) has evolved independently. An example is the development of a four-cavity heart in birds and mammals.
  • Convergence: in this case, the homoplastic trait is not present in the common ancestor. The structures originated by convergence are called analogy. An example is the wings of insects and birds.
  • Secondary loss or reversion: consist on the reversion of a trait to a state that looks ancestral. So, it looks and old state but, in fact, is derived.

paralelismo, convergencia, reversion
Biological parallelism, convergence and reversion (Picture: Marc Arenas Camps).

There are different types of traits that are used to order living beings: morphological, structural, embryological, palaeontological, ethological, ecological, biochemical and molecular.

Species that share derived states of a trait constitute clades and the trait is known as synapomorphy. Synapomorphies are traits that were originated in a common ancestor and are present in that ancestor and all its descendants. So, mammary glands are a synapomorphy of mammals.

animalia54
Mammary glands are a synapomorphy of mammals (Picture: Tiempo de éxito).

After the selection of traits, the several classification schools use them in different ways to get the best relationship between living beings.

REFERENCES

  • Notes of the subject Advanced Biology Basics, Degree in Biology (University of Barcelona).
  • Hickman, Roberts, Larson, l’Anson & Eisenhour (2006). Principios integrales de zoología. Ed. McGraw Hill (13 ed).
  • Izco (2004). Botánica. Ed. McGraw Hill (2 ed).
  • Shnek & Massarini (2008). Biología. Ed. Médica Panamericana (7 ed).
  • Vargas (2009). Glosario de Cladística: Introducción a la sistemática filogenética.
  • Cover picture: Tree of life mural, Kerry Darlington

Difusió-anglès

Symbiosis: relationships between living beings

Predation, parasitism, competition… all living beings, besides interacting with the environment, we relate to other living beings. What types of relationships in addition to those you know? Do you feel like to know them?

INTRODUCTION

The group of all living beings in an ecosystem is called biocenosis or community. The biocenosis is formed in turn by different populations, which would be the set of individuals of the same species occupying an area. For survival, it is imperative that relations between them are established, sometimes beneficial and sometimes harmful.

INTERESPECIFIC RELATIONSHIPS

They are those that occur between individuals of different species. This interaction it is called symbiosis. Symbiotic relationships can be beneficial to a species, both, or harmful to one of the two.

Detrimental to all the species involved:

Competition: occurs when one or more resources are limiting (food, land, light, soil …). This relationship is very important in evolution, as it allows natural selection acts by promoting the survival and reproduction of the most successful species according to their physiology, behavior …

Las selvas son un claro ejemplo de competencia de los vegetales en busca de la luz. Selva de Kuranda, Australia. Foto de Mireia Querol
Rainforests are a clear example of competition between vegetals in the search for light. Kuranda rainforest, Australia. Photo by Mireia Querol

One species has benefits and the other is detrimented:
  • Predation: occurs when one species (predator) feeds on another (prey). This is the case of cats, wolves, sharks

foca, león marino,
Great white shark (Carcharodon carcharias) jumping to depretade a marine mamal, maybe a sea lion. Photo taken from HQ images.

  • Parasitism: one species (parasite) lives at the expense of other (host) and causes it injury. Fleas, ticks, pathogenic bacteria are the best known, but there are also vertebrate parasites, like the cuckoo that lay their eggs in the nests of other birds, which will raise their chicks (brood parasitism). Especially interesting are the “zombie parasites”, which modify the behavior of the host. Read this post to learn more!

    Carricero (Acrocephalus scirpaceus) alimentando una cría de cuco (Cuculus canorus). Foto de Harald Olsen
    Reed warbler (Acrocephalus scirpaceus) feeding a cuckoo’s chick (Cuculus canorus). Photo by Harald Olsen

    Parasites that live inside the host’s body are called endoparasites (such as tapeworms), and those who live outside ectoparasites (lice). Parasitism is considered a special type of predation, where predator is smaller than prey, although in most cases does not cause the death of the host. When a parasite causes illness or death of the host, it is called pathogen.

    Cymothoa exigua es un parásito que acaba sustituyendo la lengua de los peces por su propio cuerpo. Foto de Marcello Di Francesco.
    Cymothoa exigua is a parasite that replaces the tongue of fish with their own body. Picture by Marcello Di Francesco.

Kleptoparasitism is stealing food that other species has caught, harvested or prepared. This is the case of some raptors, whose name literally means “thief.” See in this video a case of kleptoparasitism on an owl:


Kleptoparasitism can also occur between individuals of the same species.

One species has benefits and the other is not affected:
  • Commensalism: one species (commensal) uses the remains of food from another species, which does not benefit or harm. This is the case of bearded vultures. It is also commensalism the use as transportation from one species over another (phoresy), as barnacles attached to the body of whales. The inquilinism is a type of commensalism in which a species lives in or on another. This would apply to the woodpeckers and squirrels that nest in trees or barnacles living above mussels. Finally, metabiosis is the use of the remains of a species for protection (like hermit crabs) or to use them as tools.

    El pinzón carpintero (Camarhynchus pallidus) utiliza espinas de cactus o pequeñas ramas para extraer invertebrados de los árboles. Foto de
    The woodpecker finch (Camarhynchus pallidus) uses cactus spines or small branches to remove invertebrates from the trees. Picture by Dusan Brinkhuizen.

    Both species have benefits:
  • Mutualism: the two species cooperate or are benefited. This is the case of pollinating insects, which get nectar from the flower and the plant is pollinated. Clownfish and anemones would be another typical example, where clown fish gets protection and food scraps while keeps predators away and clean parasites of the sea anemonae. Mutualism can be optional (a species do not need each other to survive) or forced (the species can not live separately). This is the case of mycorrhizae, an association of fungi and roots of certain plants, lichens (mutualism of fungus and algae), leafcutter ants

    Las hormigas Atta y Acromyrmex (hormigas cortadoras de hogas) establecen mutualismo con un hongo (Leucocoprinus gongylophorus), en las que recolectan hojas para proporcionarle nutrientes, y ellas se alimentan de él. Se trata de un mutualismo obligado. Foto tomada de Ants kalytta.
    Atta and Acromyrmex ants (leafcutter ants) establish mutualism with a fungus (Leucocoprinus gongylophorus), in which they gather leaves to provide nutrients to the fungus, and they feed on it. It is an obligate mutualism. Photo taken from Ants kalytta.

INTRAESPECIFIC RELATIONSHIPS

They are those that occur between individuals of the same species. They are most beneficial or collaborative:

  • Familiars: grouped individuals have some sort of relationship. Some examples of species we have discussed in the blog are elephants, some primates, many birds, cetaceans In such relationships there are different types of families.
  • Gregariousness: groups are usually of many unrelated individuals over a permanent period or seasonal time. The most typical examples would be the flocks of migratory birds, migration of the monarch butterfly, herds of large herbivores like wildebeest, shoal of fish

    El gregarismo de estas cebras, junto con su pelaje, les permite confundir a los depredadores. Foto tomada de Telegraph
    Gregariousness of these zebras, along with their fur, allow them to confuse predators. Photo taken from Telegraph
  • Colonies: groups of individuals that have been reproduced asexually and share common structures. The best known case is coral, which is sometimes referred to as the world’s largest living being (Australian Great Barrier Reef), but is actually a colony of polyps (and its calcareous skeletons), not single individual.
  • Society: they are individuals who live together in an organized and hierarchical manner, where there is a division of tasks and they are usually physically different from each other according to their function in society. Typical examples are social insects such as ants, bees, termites

Intraspecific relations of competition are:

  • Territorialityconfrontation or competition for access to the territory, light, females, food can cause direct clashes, as in the case of deer, and/or develop other strategies, such as marking odor (cats, bears), vocalization

    Tigres peleando por el territorio. Captura de vídeo de John Varty
    Tiger figthing for territory. Video caption by John Varty
  • Cannibalism: predation of one individual over another of the same species.

And you, as a human, have you ever thought how do you relate with individuals of your species and other species?

MIREIA QUEROL ALL YOU NEED IS BIOLOGY

REFERENCES