KID syndrome is a rare genetic condition that usually affects the skin, hearing, and eyes from infancy or early childhood. People with KID syndrome often have thick, red, scaly skin, hearing loss, and eye irritation, and early symptoms of KID syndrome may include skin changes that do not settle as expected. Not everyone will have the same experience. KID syndrome is lifelong, and some people develop serious infections, ongoing vision problems, or a higher risk of certain skin cancers. Treatment for KID syndrome focuses on long-term care, such as skin moisturizers and other skin treatments, hearing support, eye care, and close follow-up with specialists.
How many people live with Kid syndrome?
KID syndrome is thought to affect fewer than 1 in 1 million people, which suggests fewer than about 8,000 people worldwide, although exact counts are not available (Orphanet, 2024). Using that same rare-disease estimate, fewer than about 350 people may be living with KID syndrome in the United States, but this is an estimate rather than a direct count (Orphanet, 2024).
Overview
Kid syndromeSymptoms
KID syndrome often causes thick, red, scaly skin, hearing loss, and eye irritation or sensitivity to light. Many living with KID syndrome also have fragile skin and a higher risk of eye infections.
Outlook and prognosis
With KID syndrome, outlook varies. Ongoing skin, hearing, and eye care can help protect vision, comfort, and communication. Many people with KID syndrome need lifelong follow-up because infections, worsening eye damage, and skin cancer risk can affect long-term health.
Causes and risk factors
KID syndrome is usually caused by a change in the GJB2 gene, often happening for the first time in a child rather than being inherited. Risk is mainly genetic; lifestyle or environmental factors do not cause KID syndrome, but they can affect complications.
Genetic influences
Genetics are central to KID syndrome. It is usually caused by a change in the GJB2 gene, and most cases happen for the first time in one family, though the altered gene can sometimes be passed on.
Diagnosis
Diagnosis of KID syndrome usually starts with its pattern of skin, eye, and hearing findings. Doctors often confirm it with a physical exam, hearing and eye tests, and genetic testing.
Treatment and drugs
KID syndrome care focuses on protecting the skin, eyes, and hearing. Treatment may include moisturizers, medicines for skin infections or thickened skin, hearing aids, and regular eye care. Some people need close follow-up with specialists.
Symptoms
Many living with KID syndrome have a mix of hearing loss, skin changes, and eye problems that can affect communication, comfort, and vision from early life. In daily routines, this might show up as small but noticeable changes. The early features of KID syndrome often begin in infancy or childhood, but the pattern and severity can vary widely.
Many people with KID syndrome are born with hearing loss or develop it very early in life. It can range from moderate to profound and may make spoken language harder to hear and learn.
Skin may become red, rough, and thick, especially on the face, scalp, hands, and feet. For many, this can mean soreness, itching, or cracking that makes walking or everyday tasks uncomfortable.
The front surface of the eye can become dry, irritated, and inflamed, which may cause a gritty feeling, pain, or redness. Light sensitivity and blurry vision can develop, and some people with KID syndrome have worsening vision over time.
Cracked skin and irritated eyes can make infections more likely. These infections can come back repeatedly and may add pain, drainage, or slow healing.
How people usually first notice Kid syndrome?
KID syndrome is usually first noticed in infancy or early childhood, often because a baby has thick, red, scaly skin patches and hearing problems that become clear when they do not respond to sound as expected. As children grow, doctors and families may also notice eye irritation, unusual sensitivity to light, or ongoing inflammation of the surface of the eye, which can become more obvious over time. Because the first signs of KID syndrome often involve the skin, hearing, and eyes together, this pattern is what usually leads doctors to suspect the condition early in life.
Types of Kid syndrome
No distinct types of Kid syndrome are widely recognized.
Can I slow down the onset of symptoms?
No, there is no good evidence that lifestyle changes or medicines can meaningfully delay when symptoms begin in KID syndrome, because it is a rare genetic condition that usually starts at birth or in early childhood. Healthy habits still matter for overall well-being, but they have not been shown to prevent KID syndrome or push back its onset; what can help is early, regular care for the skin, hearing, and eyes so problems are found and treated quickly, which may reduce complications but does not prevent the condition itself. Research is ongoing, and while it may not change when symptoms start, close follow-up with experienced doctors can still help many living with KID syndrome protect comfort and day-to-day function.
What genetics can tell you about symptoms
Yes. In KID syndrome, changes in a gene called GJB2 are the known cause, and these genetic differences help explain why people can have the same core pattern of skin problems, hearing loss, and eye irritation but differ in which symptoms show up first, how severe they become, and how quickly they progress. Most people are affected from birth or early infancy, but the exact variant can influence the severity of skin and eye disease and the overall course, although there can still be noticeable differences even among people with the same genetic change.
Causes and risk factors
When people ask what causes KID syndrome, the main answer is a change in the GJB2 gene. This change affects a protein that helps cells in the skin, inner ear, and eye surface communicate. It is often a new change in the child, but sometimes it is inherited from a parent, so family history is the main risk factor. Genetic testing can sometimes clarify your personal risk. Lifestyle or environmental exposures do not cause KID syndrome, but things like skin infections, dry air, and eye irritation can affect how severe the symptoms become.
What are the most common causes or risk factors?
KID syndrome is almost always caused by a change in a gene called GJB2, which helps cells in the skin, inner ear, and surface of the eye work together properly. Most cases happen as a new genetic change in the child, with no family history, but if a parent has the condition, each child has a 1 in 2, or 50%, chance of inheriting it. There are no well-known lifestyle, diet, or environmental risk factors.
Environmental and biological risk factors
When people look up risk factors for KID syndrome, the honest answer is that very few non-genetic ones are known. Researchers have not found clear environmental exposures or pregnancy-related medical factors that consistently increase the chance of KID syndrome. In most cases, there is no evidence that something a parent ate, touched, or did during pregnancy caused it.
No specific chemical, infection, radiation, or air pollution exposure has been proven to increase the likelihood of KID syndrome. Because the condition is so rare, studies have not identified a consistent outside trigger.
Common health problems during pregnancy have not been shown to directly cause KID syndrome. Routine stress, typical illnesses, and everyday activities are also not established risk factors.
Advanced maternal or paternal age is not a clearly established risk factor for KID syndrome. Unlike some congenital conditions, that link has not been firmly shown for this disorder.
Prematurity, cesarean birth, and other events around labor or delivery are not known to raise the chance of KID syndrome. It is not usually traced to something that happened during birth or newborn care.
Genetic risk factors
For many living with KID syndrome, the reason is a gene change present from birth that affects how skin, hearing, and eye-surface cells communicate. The genetic causes of KID syndrome are most often changes in GJB2, a gene that makes a cell-connection protein called connexin 26. Most cases happen for the first time in one child, but the condition can also be inherited in families. In some cases, genetic testing can give a clearer picture of your personal risk.
GJB2 gene: Most people with KID syndrome have a change in GJB2. This gene helps make connexin 26, a protein that lets nearby cells in the skin, inner ear, and cornea pass signals to each other.
New gene change: Many cases happen because the gene change is new in the child and was not inherited from either parent. This means KID syndrome can appear even when no one else in the family has it.
Dominant inheritance: KID syndrome is usually inherited in an autosomal dominant pattern, which means one changed copy of the gene can cause the condition. If a parent has the same gene change, each pregnancy has a 1 in 2, or 50%, chance of passing it on.
Family history: Having a parent with KID syndrome raises the chance that the same gene change may be present in other relatives. Still, some families have only one affected person because the variant started new in that individual.
Lifestyle risk factors
KID syndrome is not caused by lifestyle habits, but daily routines can meaningfully influence symptom control and complication risk. In practice, how lifestyle affects KID syndrome is most noticeable in the skin, eyes, ears, and risk of repeated infections. Care habits that reduce irritation, dryness, overheating, and delayed treatment can help limit worsening and support comfort and function.
Dry skin, harsh soaps, frequent friction, and skipping moisturizers can worsen cracking, pain, and scaling. Gentle cleansing and regular use of emollients may help protect the skin barrier and lower the chance of secondary infection.
Many people with KID syndrome have skin that handles heat poorly, so hot environments and heavy exertion can increase discomfort and overheating. Cooling strategies, loose clothing, and pacing activity may reduce stress on already fragile skin.
Dry air, smoke, wind, and poor eye-lubrication habits can aggravate keratitis and surface irritation. Using prescribed eye care, limiting irritant exposure, and seeking prompt care for redness or pain may help protect vision.
Inconsistent hearing-device use, poor ear hygiene, or delaying assessment of hearing changes can worsen communication problems and quality of life. Regular hearing follow-up and careful ear care can improve function and help detect complications earlier.
Risk prevention
KID syndrome is a rare genetic condition, so there is no proven way to prevent the condition itself. For many living with KID syndrome, prevention is mostly about lowering the risk of complications such as skin infections, eye damage, hearing-related delays, and skin cancer. Prevention is about lowering risk, not eliminating it completely. Because symptoms can vary, care is usually tailored to the areas most affected.
Daily skin care can help protect the skin barrier and lower the chance of cracks, pain, and infection in people with KID syndrome. Thick moisturizers, gentle cleansing, and quick treatment of cuts or sores are often central parts of care.
Skin and ear infections can become a recurring problem, so early treatment matters. If you are wondering how to prevent skin infections in KID syndrome, keeping skin clean, avoiding picking, and getting new redness, drainage, or fever checked promptly can help.
Regular eye care can help prevent worsening irritation and reduce the risk of corneal damage, which is the clear front surface of the eye. Lubricating drops, protection from dryness or smoke, and timely specialist visits are often important.
Early hearing testing and hearing support can reduce delays in speech, learning, and social development. Many people with KID syndrome benefit from repeat hearing checks because hearing needs may change over time.
Can you prevent Kid syndrome?
No, KID syndrome usually cannot be prevented because it is caused by a change in a gene, often present from birth. In some families, that gene change is inherited, while in others it happens for the first time by chance. If KID syndrome runs in your family, genetic counseling before pregnancy may help you understand the chances for a child to be born with it, but it cannot fully prevent the condition.
Transmission
KID syndrome is not an infection, so it cannot be passed from one person to another through touch, coughing, kissing, sex, or shared food and objects. Instead, the genetic transmission of KID syndrome happens through a change in a gene, most often one that helps skin and hearing cells communicate.
Many people living with KID syndrome are the first in their family to have it because the gene change happened new in them, around the time of conception. In some families, though, KID syndrome can be inherited in a dominant pattern, which means a parent with the condition can pass it to a child with a 1 in 2, or 50%, chance in each pregnancy.
When to test your genes
Genetic testing is worth discussing as soon as KID syndrome is suspected, especially in a baby or child with hearing loss, thickened or scaly skin, and eye irritation or keratitis. Confirming the diagnosis, often by testing GJB2, can help tailor hearing, eye, skin, and skin cancer monitoring, and it can inform family planning.
Diagnosis
KID syndrome is usually suspected when a child or adult has a striking combination of skin changes, hearing loss, and eye problems that affect daily life. For many, the first step comes when everyday activities start feeling harder, such as needing the TV louder, dealing with painful light sensitivity, or having thick, rough skin that keeps coming back. The diagnosis of KID syndrome is often based on these recognizable features and then confirmed with genetic testing.
Doctors look for the classic pattern of thick, scaly or warty skin, reduced or absent sweating, hearing loss, and irritation or damage on the front surface of the eyes. This combination can strongly point toward KID syndrome, especially when symptoms begin early in life.
A close skin examination helps show where the skin is thickened and whether there are areas of redness, cracking, or repeated infections. These findings can help separate KID syndrome from other inherited skin conditions.
Formal hearing tests check for sensorineural hearing loss, which is common in people with KID syndrome. In babies and young children, age-appropriate hearing exams are especially important because early hearing support can affect speech and language development.
An eye specialist looks for keratitis, which is inflammation and damage of the clear front part of the eye. They may also check for dry eyes, light sensitivity, and changes that can affect vision over time.
How is Kid syndrome diagnosed?
Doctors usually diagnose KID syndrome by looking at the pattern of symptoms and features it causes, especially thick or rough skin, hearing loss, and ongoing eye problems, along with a careful exam and medical history. Hearing tests and a detailed eye exam help show how much the ears and eyes are affected and support the diagnosis. A genetic test, usually from a blood or saliva sample, can help confirm the diagnosis, especially when the signs are not completely clear.
Stages of Kid syndrome
Kid syndrome does not have defined progression stages. That is because it is a lifelong genetic condition that can look different from one person to another, rather than moving through a set series of steps over time. Doctors usually start with a conversation about the early symptoms of Kid syndrome, such as hearing problems, ongoing skin changes, and eye irritation, along with a physical exam and hearing and eye testing. Diagnosis may be confirmed with genetic testing, and follow-up usually focuses on watching the skin, hearing, and eyes over time because these problems can vary in severity.
Outlook and prognosis
Outlook in KID syndrome varies widely and depends on the severity of skin disease, hearing loss, and eye involvement, but many affected people live into adulthood with ongoing specialist care. Prognosis is often shaped by chronic complications such as recurrent skin infections, progressive keratitis with vision loss, and significant hearing impairment that can affect communication and development. A major long-term concern is the markedly increased risk of squamous cell carcinoma of the skin and mucous membranes, which can occur at a young age and requires lifelong surveillance. Mortality is not well defined because the condition is very rare, but severe infections, aggressive skin cancers, and complications of extensive skin barrier dysfunction can be life-threatening in some individuals. Early multidisciplinary management, careful skin and eye care, hearing support, and prompt evaluation of suspicious lesions can improve quality of life and may reduce serious complications.
Long-term effects
For many living with KID syndrome, the long-term picture is often shaped by changes in the skin, hearing, and eyes rather than by one single problem. Long-term effects vary widely, so some people have milder day-to-day limits while others develop more serious complications over time. In childhood these features may be easier to spot in the skin and hearing, while in adolescence and adulthood, eye damage and cancer risk can become more important.
Thick, rough, reddened skin can persist for life and may crack, feel sore, or limit comfort with walking or daily hand use. Over time, areas of skin can become more inflamed or widespread, although severity differs from person to person.
Skin that is cracked or chronically inflamed is more prone to bacterial and fungal infections. These infections can keep coming back and may add pain, drainage, odor, or slow healing to the long-term effects of KID syndrome.
Many people with KID syndrome have permanent hearing loss that starts early in life and affects speech, learning, and everyday communication. The degree of hearing loss can vary, but it is often a major lifelong feature.
Eye involvement may begin with light sensitivity, irritation, or a gritty feeling, then progress to ongoing inflammation of the clear front surface of the eye. Some may develop scarring, clouding, or worsening vision over the years, which is one of the more serious long-term features of KID syndrome.
How is it to live with Kid syndrome?
Living with KID syndrome often means managing several challenges at once: thick, inflamed skin that can crack or become painful, hearing loss that affects communication, and eye problems that may make light uncomfortable and vision less clear. For many people with KID syndrome, daily life includes regular skin care, hearing support such as hearing aids or sign language, and close follow-up with specialists to help protect vision, prevent infections, and ease discomfort. This can also shape family and school or work life, because loved ones may help with treatments, communication, and medical visits, but with the right support many people build routines that make life more manageable and help them stay connected to others.
Treatment and drugs
Kid syndrome is treated by managing its main day-to-day problems rather than curing the condition itself. Care usually includes regular skin care with thick moisturizers, treatment for skin infections when they happen, and close follow-up for eye problems and hearing loss, often with a team that may include skin, eye, and hearing specialists. Doctors sometimes recommend a combination of lifestyle changes and drugs, such as antibiotic or antifungal medicines for infections, lubricating eye drops, and in some cases prescription skin medicines for severe thickening or cracking. Because early symptoms of Kid syndrome can worsen over time, treatment is usually adjusted as needs change, with hearing aids or other hearing support added when helpful.
Can you cure Kid syndrome?
No, KID syndrome cannot currently be cured because it is a lifelong genetic condition. Treatment focuses on helping with day-to-day problems, such as protecting and moisturizing the skin, treating infections, supporting hearing, and caring for eye problems. Many people living with KID syndrome need regular follow-up, and care can improve comfort and help prevent complications, but it does not remove the condition itself.
Non-drug treatment
KID syndrome can affect everyday life in several ways at once, especially hearing, skin comfort, and eye health. Managing this condition often means building a steady care routine with several specialists rather than relying on one single treatment. Non-drug care for KID syndrome aims to protect vision and hearing, ease skin problems, support communication, and help prevent complications. Because symptoms vary, the best plan depends on age, severity, and which parts of the body are most affected.
Daily skin care helps reduce dryness, cracking, buildup, and discomfort that can make walking, dressing, or sleeping harder. Gentle bathing, regular moisturizing, and soft clothing can protect the skin barrier and lower irritation. For many families, daily care for KID syndrome skin and eyes becomes part of the routine.
Regular visits with an eye specialist are important because KID syndrome can damage the clear front surface of the eye and affect vision over time. Moisture protection, careful lid hygiene, and shielding the eyes from wind, dust, and bright light can help reduce irritation. Some people may also need procedures if scarring or other eye complications develop.
Many people with KID syndrome have significant hearing loss, so early hearing testing and ongoing hearing care matter. Hearing aids, cochlear implants, and other listening devices can improve access to sound, speech, and learning. Not every approach works the same way, so settings and devices often need adjusting over time.
Speech therapy and communication support can help children and adults make the most of their hearing and language skills. Some may also find sign language, cued speech, or visual communication tools useful in daily life. Family members often play a role in supporting new routines and communication strategies.
Your genes may have an impact on how drugs work for you
For people living with KID syndrome, treatment is usually aimed at managing skin infections, dry or thickened skin, eye problems, and hearing loss, and there is no well-established proof that the gene change causing the condition reliably changes how most of these medicines work. In day-to-day life, this means doctors usually choose treatments based on symptoms, age, and how the skin or eyes respond over time, rather than using a genetic test to pick a medicine. While the broader field of using genes to guide drug choice, called pharmacogenomics, is important in some parts of medicine, it is not a routine part of care for KID syndrome at this time.
Pharmacological treatments
Treatment for KID syndrome usually focuses on the skin, eyes, and infections rather than curing the condition itself. Many living with KID syndrome need a mix of medicines over time, because symptoms can change from childhood into adult life. Finding the right medication can be a process of trial, patience, and adjustment. Doctors also watch closely for side effects, especially with long-term treatment.
Acitretin and isotretinoin are oral medicines that can reduce thick, scaly skin and may make daily skin care easier for people with KID syndrome. They are often used for more severe skin symptoms, but they need careful monitoring because they can affect the liver, blood fats, and pregnancy safety.
Topical tretinoin or tazarotene may help soften smaller areas of thickened skin, especially when plaques crack or make movement uncomfortable. These medicines can irritate sensitive skin, so doctors usually start slowly and adjust how often they are used.
Urea, salicylic acid, and ammonium lactate are medicated creams or lotions that help loosen built-up scale and smooth rough skin. For many, this can mean less pulling, less cracking, and some relief from the early symptoms of KID syndrome that affect walking or using the hands.
Topical antibiotics such as mupirocin, and sometimes oral antibiotics like cephalexin or clindamycin, are used when damaged skin becomes infected. This can be important in KID syndrome because breaks in the skin may let bacteria in more easily.
Genetic influences
For many living with KID syndrome, the skin, hearing, and eye problems usually trace back to a change in the GJB2 gene. This gene helps nearby cells communicate, so when it does not work properly, the skin, inner ear, and the clear front surface of the eye can all be affected. KID syndrome is usually inherited in an autosomal dominant pattern, which means one altered copy of the gene is enough to cause the condition, although many children with KID syndrome are the first in their family to have it because the change happened new in them. DNA testing can sometimes identify these changes. Knowing the genetic cause of KID syndrome can help families understand the chance of it happening again, especially if a parent also has KID syndrome, and it can guide genetic counseling and long-term care.
Is Kid syndrome genetic?
Genetics are central to KID syndrome. It is usually caused by a change in the GJB2 gene, and most cases happen for the first time in one family, though the altered gene can sometimes be passed on.
Having a genetic risk is not necessarily a diagnosis
Genetic variants are a usual part of human biology and are common throughout the general population. Most do not have a direct effect on health and are simply part of normal human diversity. For many genes, having a variant connected to a condition suggests a possible association, not a definite diagnosis, especially when several genes and environmental factors are involved. In some situations, though, a single well-characterized variant in a particular gene can be enough to confirm the diagnosis.
Pharmacogenetics—how genetics influence drug effects
For many people with KID syndrome, treatment is shaped first by everyday issues like thick or fragile skin, repeated infections, eye irritation, and hearing problems, so genetic testing usually helps guide overall care more than it points to one exact medicine. Most cases are linked to a change in the GJB2 gene, and confirming that result can help doctors plan earlier skin, eye, and hearing support and watch more closely for complications. Not every difference in response is genetic, but in KID syndrome the underlying gene change can influence how severe the condition is, which may affect how cautiously certain skin treatments or procedures are used. If you are wondering how genes affect treatment for KID syndrome, the answer is usually through diagnosis, prognosis, and monitoring rather than classic drug matching. At this point, there is no widely used pharmacogenetic test that can reliably tell doctors which antibiotic, eye drop, or skin medicine will work best for KID syndrome, so treatment is still adjusted mainly by symptoms, response, and side effects.
Interactions with other conditions
For many living with KID syndrome, the condition can affect more than the skin, ears, and eyes, and this can shape overall health in important ways. The fragile skin barrier often makes bacterial or fungal skin infections more likely, so a rash that is already sore or cracked may become more inflamed and harder to heal. Ongoing eye surface problems can overlap with severe dry eye and repeated irritation, which may raise the risk of corneal damage and vision loss over time. Doctors call it a comorbidity when two conditions occur together, and in KID syndrome this can include hearing loss alongside speech, learning, or social communication challenges, especially in children who do not get early hearing support. People with KID syndrome also have a higher risk of some skin cancers, particularly squamous cell carcinoma, so new lumps, nonhealing sores, or changing thickened areas need prompt medical review. Because the early symptoms of KID syndrome can resemble eczema, chronic infections, or other skin disorders, coordinated care with dermatology, eye, hearing, and primary care specialists is often important.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
What other conditions can cause similar symptoms to Kid syndrome?
Other rare inherited conditions that affect the skin, hearing, and sometimes the eyes can look a lot like KID syndrome, especially Clouston syndrome, Vohwinkel syndrome, and some forms of ectodermal dysplasia, which are conditions that change how the skin, hair, nails, sweat glands, and ears develop. Doctors may also think about other causes of very dry, thick, scaly skin, such as certain types of ichthyosis, as well as severe eczema or long-lasting skin infections, depending on which symptoms are most noticeable.
History
For many living with KID syndrome, the history of the condition helps explain why diagnosis was once slow and confusing. Doctors first recognized it by noticing a pattern rather than understanding the cause: people had unusual skin changes, hearing loss from early life, and later, in some cases, eye problems that could affect vision. These features did not always appear in the same way or at the same age, so early reports were often incomplete.
In recent decades, awareness has grown, but the condition began to take shape in the medical literature during the 20th century, when physicians described patients with this distinctive combination of skin, hearing, and eye findings. The name KID syndrome came from the first letters of keratitis, ichthyosis, and deafness, although doctors later realized that the skin changes are not always exactly the same as classic ichthyosis. As medical science evolved, KID syndrome came to be recognized as a rare disorder with a broad range of severity. Some people have more serious eye disease, while others are affected mainly by skin problems and hearing loss.
This growing understanding changed everyday care. Instead of viewing the skin, hearing, and eye issues as separate problems, clinicians began to connect them, which made earlier diagnosis and more coordinated support possible. For families, that could mean moving from repeated visits for dry, thickened skin or early hearing concerns to a clearer explanation of what was linking them together.
Later research showed that KID syndrome has a genetic basis, which helped confirm that the condition was a distinct syndrome rather than a chance mix of symptoms. That work also helped explain why the early symptoms of KID syndrome can look different from one person to another. Today, the history of KID syndrome reminds us that careful observation over time often comes before full scientific understanding, and that older descriptions, while limited, laid the groundwork for better diagnosis, counseling, and treatment.