“An 8-year-old girl is the first unique case of chromosome 6p deletion. She can not feel pain, hunger, and the requirement of sleep. It is a congenital condition in which some of the parts of chromosome 6 deleted during the process of cell division.”
A chromosome is a complex network of proteins and DNA. We humans have 46 number of chromosomes, however, the number of chromosomes varies among organisms. How DNA fits inside the nucleus? Read the article: DNA packaging in eukaryotes
The chromosome has three distinct parts; centromere, arms, and telomeres. Each part performs a specific function, for instance, the telomere sequences help to maintain replication properly.
Likewise, the centromere helps chromosomes to arrange properly during the process of replication, the two arms (“p” arm and “q” arm) have genetic information in the form of genes and the telomeres are the cap of the chromosomes which protects the genetic information of it.
Depending upon the location of the centromere the chromosomes are divided into several categories such as acrocentric, metacentric or submetacentric. Chromosome 6 is a medium submetacentric chromosome having the “p” arm slightly shorter than the “q” arm.
Take a look at the different forms of chromosome 6 depending upon its length:
Mutations are the reason for occurring abnormalities. Those mutations are either gene mutations or chromosomal mutations. Read our article on the present topic: Genetic Mutations- Definition, Types, Causes and Examples.
Common gene mutations are deletion, duplication, single nucleotide polymorphism and insertion while common chromosomal mutations are change in chromosome number or structure.
Structural chromosomal anomalies cause a change in chromosome structure, on the other side, numerical abnormalities change the number of chromosomes in an organism. For instance, in the case of Down syndrome, an extra number of chromosome 21 is present.
Various types of numerical chromosomal anomalies are enlisted here,
The cry-do-cat syndrome is a type of structural aberration in which some portion of the “p” arm of the chromosome 5 deleted.
Similarly, 6p deletion is such a type of structural aberration that causes several congenital problems which are very rare throughout the world. Now let’s understand some of the basics about chromosome 6.
Genetic information on chromosome 6
Chromosome 6 contains more than 1000 genes (~1200-1300 genes) with more than 170 million base pairs on it. The majority of the genes present on chromosome 6 are associated with the immune system. The genes for major histocompatibility complexes are present on it.
Read the article on Genetics of the immune system:
- Generation of Antibody Diversity
- Immunogenetics class 2: antibody diversity
- Immunogenetics class 3: T cell gene rearrangement
The major histocompatibility genes are HLA-A, HLA-B, HLA-C, HLA-DQA1, HLA-DQB1, HLA-DQ, HLA-DRA, HLA-DRB1, HLA-DRB3, HLA-DRB4, HLA-DRB5, HLA-DPA1, HLA- DPB1, HLA-Cw present on the “p” arm of chromosome 6. See the image which shows the location of the HLA genes on the p arm of chromosome 6:
The total size of chromosome 6 is 170Mb in which the short “p” arm and longer “q” arm contains a 60Mb portion and a 110Mb portion of the total size, respectively.
Chromosome 6 is involved in some of the well-known diseases such as maple syrup urine disease, Parkinson’s disease, polycystic kidney disease and Rheumatoid arthritis.
Also, ring chromosome, del 6q, del 6q16, del 6p22 and insertion in the proximal end on the p arm are some of the common types of the structural chromosomal aberration associated with chromosome 6.
Chromosome 6p Deletion:
An 8-year-old girl named Olivia Farnsworth is the first unique case of chromosome 6p deletion. The story of her came in light when she was hit by the car and injured badly. However, she had not felt pain even not cried.
Once her condition was diagnosed, her mother admitted that she doesn’t need sleep or to eat. Furthermore, she confessed that she never feels danger, pain, hunger, and need for sleep. She feels lesser emotions in comparison with other girls as well.
Doctors named her as the first “Bionic girl” for her superhuman capability. Tons of articles are available on the Internet which covered the story of Olivia Farnsworth but none of the articles explained which part of chromosome 6 or how many genes from chromosome 6 are deleted.
The cytological analysis reveals that the major portion of the “p” arm was deleted from the single copy of chromosome 6 in Olivia’s case.
The major portion of chromosome 6 is associated with the immunes system as we said. The immune system gives power to the organism to resist any pathological condition. We can feel the pain when a signal to the brain is given from the site of cut or damage.
The genes for the major histocompatibility complex are located on the p arm of chromosome 6. So hypothetically, it is possible that some of the genes from this “HLA genes clouds” may be deleted which gives the insane resistance power to Olivia.
Interestingly, other genes which are present on the chromosomes 6 mainly associated with diabetes, developmental delay, distinctive facial features, intellectual disability and other mantle problem but not with hunger, pain or sleep.
The severity of the phenotype depends on the size of the deleted fragment. Further, the condition is congenital and non-inherited. Other 6p deletions are reported in CCD (Cleido Cranial Dysplasia) del 6p12.3, deletion of 6p22, and terminal deletion of 6p arm.
Related article: Do Identical Twins Have The Same DNA?.
In all these deletions, the major phenotypic abnormalities are associated with developmental delay, mental retardation and intellectual disability.
Though more than 100 cases like Olivia are reported, she is the only person in the world who has all three phenotypes of “no pain, no sleep and no hunger”. Moreover, approximately, 3000 cases are reported worldwide in which chromosome 6 deletion is involved (but none of the cases is like Olivia).
“1 in 200 children born with chromosomal abnormalities worldwide”
Is she superhuman?
Most people think so but she is not. It is not power, it is her limitation.
Feel of pain and hunger is the first line of defense for our body. The pain is the signal for the danger that some portion of our body is damaged. Also, hunger is a signal for the requirement of energy for our body.
When we feel hunger, we eat. Suppose if we can not feel hunger, the carbohydrate, protein, and energy level of our body decreases and we can not feel it. We might be unconscious or dies due to hunger. Imagine the condition in which we are injured badly and we even don’t know about it. What will happen?
Further, due to lack of sleep, the working efficiency of our brain can be decreased.
“If we do not sleep for a longer time, we can not differentiate between reality and illusion.”
So scientifically, it is not a superpower. Still, she is different from us. We can say that she is the “naturally genetically modified organism”. Nonetheless, the reason for the less hunger and sleeplessness is not cleared.
Interesting article: 20 Incredible DNA Facts: The 20th One Is Actually Shocking.
The chromosome 6p deletion case of Olivia is a unique and only case in the world.
I personally believe that mutation or any other alteration gives the survival power to the organism and Olivia is the example of it. In the future, we can hope that Non-oxygen depended GMOs can be created. And, that will change the fate of the human race.