Imagine this. A young teenager, 17, years old, who is fully developed. Now imagine this, the same teenager has a fully developed extra set of limbs and a pelvis. That extra set of pair is attached with chest artery. But, how can this happen?

While it is extremely rare, and has a chance of less than one case occurring per 100,000 births. Such things do happen. This is called parasitic twin.

What Is A Parasitic Twin?

It is an extremely rare type of cojoined twin where a baby is born with an underdeveloped twin attached to its body. This condition is also known as vestigial twins. The condition is very closely related to conjoined twins, where babies are connected at birth and share organs. However, the main difference is that in conjoined twins, there are two developed babies, whereas in parasitic twins, only one is fully developed, other one is underdeveloped and non functional.

In such a case, the twin who is developed is medically known as the autositic or the dominant twin. The dominant twin is healthy in most aspect but may have extra tissue, organs, or limbs from the parasitic twin.

The parasitic twin may be attached with the dominant twin through several places. The common joints are at the head, torso, chest, pelvis, buttocks, or back. In these cases, the parasitic twin is not alive and they die either in the womb or during the childbirth.

Doctors Remove Parasitic Twin

Now, let's go back to the case we referred to, where a young teenager had an extra pair of limbs attached to chest. The teenager who has not been named is from Uttar Pradesh's Unnao neighbourhood, and was treated in AIIMS, Delhi. The team of doctors successfully removed the extra set of limbs from his body.

Dr Asuri Krishna, who led the team of specialist who surgically removed the extra limbs told the BBC that only 40 to 50 cases of parasitic twins have been documented in world medical literature, and in those cases, the surgery had been attempted on children. The doctor said that without much medical literature to guide them, the team of doctors depended on "intuition, skill and knowledge".

The doctor shared that the child had two fully formed legs, buttocks and external genitalia, which weighed around 15kg "protruding from his abdomen".

How Was The Surgery Performed?

The doctor shared that first they identified how interconnected the parasitic and host twins were. The doctors took scans and found that parasitic twin was attached to the teen's breastbone. The blood was being supplied from a vessel in his chest. However, "there wasn't much connection with other main organs like the liver or kidneys," said Dr Krishna. The team also found a large cyst in the teen's abdomen.

Then the surgery was performed in two stages. In the first stage, the parasitic twin was removed. Then the cystic mass was extracted from the surrounded area. The entire surgery was completed in two and a half hours and the team of doctors included radiologists, anaesthetists, and plastic surgeons.

The biggest challenge was when the teen's blood pressure dropped as 30 to 40% of his blood flowed to the parasitic twin, however, the doctors were prepared for it and they stabilized him.

In 2025, thanks to climate change, rapid urbanization, and frequent travels, new viruses, their strains, and infections have spread frequently. Infections have affect millions and some diseases have come back with their new strains, which have been more contagious, whereas other diseases are finding new ways to emerge.

As we look back at the year, which is about to end in just another month, let us look back at the top 5 infectious diseases of 2025.

Respiratory Infections

In 2025, respiratory infections were the most widespread, with new COVID-19 variants emerging every now and then. Along with this common flu too has emerged. This has weakened immunity and made elderly and infants, and people with comorbidities more vulnerable to the diseases.

The new COVID variants in India are linked with the JN.1 variant and its sub-variants like LF.7 and NB.1.8. The COVID variants in the UK which were active were XFG, NB.1.8.1, or known as the Stratus and Nimbus variants. Other variants were XFG.3, XFG.5, and XFG.3.4.1.

Tuberculosis (TB)

Tuberculosis still continues to be a major infectious disease in 2025, especially in countries like India. As per the World Health Organization (WHO), tuberculosis caused 1.25 billion deaths in 2023. It becomes the world's leading infectious disease after COVID-19.

Each day, close to 3,425 people lose their lives to TB, and close to 30,000 people fall ill with this preventable and curable disease. About 10.8 million people got TB in 2023, which include 6 million, 3.6 million women, and 1.3 million children.

Dengue and other mosquito-borne infections

Mosquito-borne diseases like dengue, chikungunya, malaria, and Zika continued to rise in 2025. The reason being changing weather patterns. Dr Sanjeev Bagai, Chairman of Nephron Clinic, and Senior Consultant Pediatrician and Nephrologist points out that earlier the mosquito-borne diseases were seasonal, however, due to rapid urbanization and climate changes, these diseases have stayed all round the year.

Hepatitis Infections

Hepatitis B and Hepatitis C are among the most common Hepatitis infections in 2025. However, there have been outbreaks of Hepatitis A and E in unsafe water and food. Chronic hepatitis can also damage liver and also lead to cancer. It is a concern because it spreads through contaminated food, unsafe water, blood, and sexual contact. While many people may not show symptoms until serious liver damage occurs.

Symptoms also include jaundice, dark urine, fatigue, nausea, and abdominal pain.

Gastrointestinal Infections

Food- and water-borne infections are still common across the world. Illnesses like salmonella, cholera, rotavirus, and norovirus often spread in areas where hygiene, sanitation, and food safety are poorly maintained.

Why are these infections risky?

They can spread extremely fast, especially among children and older adults. Severe diarrhea and vomiting can lead to dangerous dehydration if not treated in time.

What symptoms should you look out for?

Persistent diarrhea, vomiting, stomach cramps, fever, and signs of dehydration. The best prevention is simple: drink clean water, wash hands regularly, and eat properly cooked food.

When we think about cancer risk, it’s natural to wonder, “is it genetic?”

The truth is, sometimes it is, but in many cases, cancer develops from a mix of lifestyle, environmental factors, and DNA changes that occur over a lifetime. Understanding the difference between inherited genetic risks and those acquired along the way can help people make smarter decisions about screening, prevention, and treatment, and empower families to take proactive steps for their health.

Inherited genes or life choices?

Cancer arises from a series of changes/mutations in cells that disrupt normal growth control. Many of these changes happen over a person’s lifetime, influenced by exposures (like tobacco, UV rays, infections), aging, and random DNA errors. These are called “somatic mutations” and occur in our tissues—they are not inherited, and are not passed to children.

By contrast, a smaller fraction of cancers are influenced by inherited mutations called “germline mutations”; these are changes in the DNA that you are born with, and are present in every cell of your body. These mutations can predispose someone to cancer by impairing DNA repair, controlling cell division, or through other mechanisms. Approximately 5–10% of all cancers are thought to have a strong hereditary component.

So, while your DNA can influence your cancer risk, most cancers don’t occur because of an inherited gene defect. And even when a germline mutation is present, environment, lifestyle, and chance usually play significant roles in whether cancer actually develops.

Recognizing hereditary cancer syndromes

When should we suspect hereditary cancers? Here are red flags:

A strong family history of cancer, especially the same type (e.g. multiple members with breast cancer, or several relatives with colon cancer).

• Early-onset cancer, e.g. diagnosis before the age of 50 or 40 years.
• Multiple primary cancers in the same person (e.g., ovarian + breast).

Rare cancers or specific tumor types tied to known syndromes (e.g. medullary thyroid cancer, male breast cancer, pancreatic cancer in some families).

Known syndrome features, such as colon polyps and colon cancer in Lynch syndrome.

In such cases, genetic testing can identify mutations in genes like BRCA1/2, Lynch syndrome genes (MLH1, MSH2, MSH6, PMS2, EPCAM), TP53, PALB2, and others. Identifying carriers has implications for targeted screening (e.g. colonoscopic surveillance or mammography at regular intervals), preventive surgery like mastectomy, and sometimes therapy in case cancer does develop.

How do hereditary mutations lead to cancer?

Imagine your cells are factories, following a strict set of instructions (your DNA). Inherited mutations can mean that a “safety check” is broken from the start. For example:

A mutation in the BRCA1 or BRCA2 genes weakens the cell’s ability to repair DNA. Over time, unrepaired damage accumulates, raising the risk of developing breast, ovarian, prostate, and pancreatic cancer.

Mutations in DNA mismatch repair genes (as in Lynch syndrome) allow errors during DNA copying to persist, boosting mutation load and increasing the risk of developing colon, endometrium, stomach, and other cancers.

But even when a high-risk mutation is present, cancer doesn’t appear overnight. Additional “hits”, or more mutations, microenvironment changes, hormonal exposures, or lifestyle factors need to typically accumulate before cells turn cancerous.

Why does hereditary information matter?

You might ask: if it’s a small percentage of cancers, does knowing about hereditary risk make a difference?

The answer is, yes, absolutely. Knowing your hereditary risk of cancer has some important benefits:

Prevention & early detection: If you carry a pathogenic mutation, you can undergo more frequent surveillance, chemoprevention (e.g. tamoxifen for breast cancer), or risk-reducing surgeries (e.g. prophylactic mastectomy or oophorectomy).

Therapeutic choices: Certain inherited mutations also influence how cancers respond to therapy. For example, PARP inhibitors are effective in tumors with BRCA-related homologous recombination deficiency (HRD). Thus, knowing that a patient has a germline BRCA mutation may alter drug selection.

Family risk & cascade testing: Identifying a hereditary mutation allows cascade testing, where close relatives can also get genetic testing done. This helps them understand risks and take prevention measures before cancer develops.

Clinical trial access: Many modern trials require knowledge of inherited DNA defects. Patients with known germline mutations may qualify for therapies designed precisely for those DNA repair vulnerabilities.

However, it is also important to understand that absence of a germline mutation does not mean absence of risk. Many cancers are driven purely by somatic mutations, and many hereditary variants remain undiscovered or classified as Variants of Uncertain Significance (VUS). Testing negative for known genes does not guarantee immunity.

Also, hereditary risk is not absolute: a person may carry a mutation but never develop cancer, due to protective factors like healthy lifestyle, background genetics, or luck. Interpretation must be done thoughtfully, ideally with genetic counselling.

Conclusion

While hereditary mutations play a role in a minority of cases, their impact on prevention, therapy, and family planning can be profound. Knowing whether cancer “came from your DNA” is often less important than using that knowledge wisely—both for patients and their relatives.

As we move deeper into the era of precision medicine, clinicians and patients alike should appreciate that hereditary and somatic worlds coexist, and that DNA insight is a tool—not a verdict.

In a medical first, surgeons in China have successfully transplanted a gene-edited pig liver into a living human to temporarily support his failing liver. The procedure showed that a pig liver can function inside the human body for several weeks and act as a “bridge” for patients who have no other treatment options.

The patient was a 71-year-old man with severe hepatitis B–related liver cirrhosis and a large liver cancer tumor. His condition made traditional surgery or a human liver transplant impossible. With no donor organs available and his health rapidly worsening, doctors decided to try the experimental pig liver transplant under compassionate use.

How the Pig Liver Was Engineered

The donor organ came from a specially bred Diannan miniature pig. Scientists had made 10 specific genetic changes to the animal so its liver would be more compatible with the human body.

These changes included:

• Removing pig genes that usually trigger strong immune rejection
• Adding seven human genes to help the liver work smoothly with human blood, immunity and clotting systems

Once the liver was connected to the patient’s blood supply, it began working immediately. It produced bile, supported metabolism, made important proteins like albumin and helped with blood clotting. Early tests showed stable liver and kidney function, and there were no signs of sudden or severe rejection, which is usually the biggest challenge in pig-to-human organ transplants.

A Serious Complication Emerges

But the case also revealed a major challenge for future xenotransplants. After about a month, the patient developed a condition called xenotransplantation-associated thrombotic microangiopathy (xTMA).

This complication caused:

• Breakdown of red blood cells
• A drop in platelets
• Activation of the complement system (part of the immune response)
• Small blood clots forming in blood vessels

Doctors tried multiple treatments, including blood thinners, a complement-blocking drug (eculizumab) and plasma exchange. However, the condition continued to worsen.

On day 38, the medical team decided to remove the pig liver to protect the patient. Fortunately, during this period, the patient’s remaining left portion of his own liver had grown and was able to take over enough liver function. After the pig liver was removed, the signs of xTMA gradually resolved.

The patient later developed complications unrelated to the xenotransplant — mainly repeated bleeding in his digestive tract due to his pre-existing liver condition — and he died on postoperative day 171.

What This Means for the Future

Researchers conclude that this groundbreaking case proves pig-to-human liver transplantation is technically possible and can meaningfully support patients for weeks. This offers hope for people with acute liver failure or advanced liver cancer who have no donor organs available.

However, major barriers remain. The biggest challenges highlighted include:

• xTMA
• Blood clotting incompatibilities
• Overactivation of the immune system
• The need for better gene-editing strategies

Scientists say more work is needed before such transplants can become routine. But this case sets an important foundation for future clinical trials and brings the medical world a step closer to using animal organs to save human lives.