Condition AZ: p

The first signs of Potter syndrome are evident in the womb before one month of fetal development. At this stage, the ureteral bud, which forms the kidneys, fails to develop. The urine that is produced by the kidneys during pregnancy creates the amniotic fluid (a yellowish liquid that surrounds the unborn baby during pregnancy). If the uteral bud fails to develop, like in Potter syndrome, little amniotic fluid is produced as a result. The production of amniotic fluid during pregnancy is vital to the development of the baby’s lungs. In Potter syndrome, the lungs of the baby do not develop fully because of a lack of amniotic fluid (this is known as oligohydramnios). During pregnancy, babies may appear to have normal weight and size for their age because the placenta performs the filtering work of the kidneys. However, babies die either during birth or very shortly thereafter mainly because of pulmonary hypoplasia (underdevelopment of the lungs).

Potter syndrome occurs twice as frequently in males compared with with females. There is no known treatment for classical Potter syndrome and it is always fatal due to the underdevelopment of the baby’s lungs. In some Potter-like cases where the kidneys are present but are severely malformed, the kidneys may have produced enough urine during pregnancy, and therefore sufficient amniotic fluid, for the lungs to develop enough for the baby to survive. In this situation, babies may survive if kidney function can be supported with a form of dialysis, however, this is technically very challenging.

Inheritance patterns
In most cases, Potter syndrome occurs sporadically in which case it is not likely to happen again in the same family. In some cases, Potter syndrome may be inherited as an autosomal dominant trait. Potter syndrome is more common in infants born of a parent who has a kidney malformation, particularly unilateral renal agenesis (absence of one kidney). Genetic counselling is recommended after the birth of a baby with Potter syndrome.

Prenatal diagnosis
Potter syndrome may be identified on ultrasound examination in subsequent pregnancies. As Potter syndrome is frequently associated with clinically silent anomalies of the kidneys, ultrasound examination of the kidneys and urinary tract would be recommended for the parents in the first instance.

Renal Agenesis UK

Email: [email protected]
Website: renalagenesisuk.com

Renal Agenesis UK is a UK based organisation providing information and support to parents, family and friends who have had a baby diagnosed with bilateral renal agenesis.

Group details added March 2019.

British Porphyria Association

Helpline: 0300 30 200 30
Email: [email protected]
Website: porphyria.org.uk

The Association is a Registered Charity in England and Wales No 1089609. It provides information and support to families and individuals affected by porphyria. 

Group details last reviewed March 2026.

The aetiology, in children, is thought to be that there is a localised destruction of brain tissue due to a number of causes but potentially including toxaemia, maternal injuries, infection, hypoxic injury or even intra-uterine intra-cerebral haemorrhage. It has been seen after multiple taps of the ventricles (fluid cavities inside the brain), to relieve raised intracranial pressure. Its overall incidence is unknown, aetiology must be multi-factorial and some series suggest that there is a risk that a patient with porencephaly has a two to four per cent chance of having a child with a neural-tube defect.

People with mature brains can get similar cysts developing due to loss of brain tissue after brain haemorrhages, strokes and head injuries. These cysts, like porencephalic cysts, are what is left behind by the normal process of the brain clearing away dead tissue as part of the normal healing processes of the body.

There is no specific treatment other than for conditions that may have caused it. There may be seizures but most of the time these present as incidental findings.

Inheritance patterns
None.

Prenatal diagnosis
None is available at present. Cysts can sometimes be detected by ultrasound scanning.

There is no support group for porencephaly in the UK. Families can use Contact’s freephone helpline for advice, information and, where possible, links to other families. To meet other families with disabled children, join Contact’s closed (private) Facebook group.

Symptoms typically begin in the late teens or early twenties and can include:

• irregular periods, light periods or no periods at all
• infertility due to irregular or no ovulation
• hirsutes (excess hair growth)
• persistent acne
• thinning of scalp hair
• weight gain.

There are a number of possible causes and there is no doubt that PCOS runs in families. Insulin is a hormone that controls blood sugar levels and it also acts on the ovaries causing them to produce testosterone. Some women with PCOS have insulin resistance, therefore, cells in the body are resistant to the effect of a normal level of insulin and so more insulin is produced to keep the blood sugar normal. Increased insulin causes the ovaries to make too much testosterone and combined the high level of insulin and testosterone prevents ovulation. An increased testosterone level in the blood causes excess hair growth on the body, thinning of the scalp hair and contributes to weight gain.

Luteinising hormone (LH) is made in the pituitary gland. It stimulates the ovaries to ovulate and works alongside insulin to promote testosterone production. A high level of LH is found in about 4 in 10 women with PCOS. Although PCOS is not strictly inherited from parent to child, it may run in some families.

A cream called eflornithine may be prescribed to rub on areas of skin with excessive hair growth. It works by counteracting an enzyme involved in making hair. The contraceptive pill Dianette is commonly prescribed to regulate periods, to help reduce hair growth and to reduce acne in women with PCOS. The contraceptive pill Yasmin has been shown to help if Dianette is not suitable, although any combined contraceptive pill can be effective. Other antitestosterone drugs are sometimes advised by a specialist if the above treatments do not help.

It is important to ensure that menstruation occurs regularly to prevent abnormal thickening of the womb lining, this can also be achieved with the combined contraceptive pill or alternatively a hormone called progesterone. If fertility is desired then drugs may be required to help stimulate regular ovulation – this requires careful supervision by a specialist infertility clinic.

Losing weight can help to reduce insulin-resistance, thus reducing testosterone levels. In women who may be at risk of type II diabetes because of insulin resistance, metformin, an insulin sensitising drug may be prescribed.

Inheritance patterns
PCOS is known to run in families, however, the genetic factors responsible and inheritance pattern are yet to be determined.

Prenatal diagnosis
None.

Verity

Email: [email protected]
Website: verity-pcos.org.uk

Verity is a Registered Charity in England and Wales No. 1097599. It provides information and support for women with Polycystic Ovary Syndrome. Verity offers a discussion board where women can give and receive peer support, and organises twice yearly conferences. 

Group details last updated September 2014.

The majority of infections are characterised by a mild fever often with vomiting or diarrhoea. Weakness or complete paralysis of any of the skeletal muscles appears in a minority of subjects, but this may develop rapidly. After a few days or weeks the weakness begins to improve and may continue to do so for one to two years.

Post-polio syndrome
It has recently been recognised that after an interval of at least 35 years after the acute infection, a condition known as the post-polio syndrome may develop. This is due to dying back of the peripheral nerve fibres which were damaged, but regenerated after the acute illness. This causes weakness, pain and fatigue in muscles which were previously affected. Post-polio syndrome occurs in around 50 per cent of those who have had polio, but in 80 per cent of these it is either static or only slowly progressive. Specialist advice about how to adapt the lifestyle to minimise the risk of the progression of this syndrome is often effective. Respiratory support, usually with a non-invasive ventilator system used at night, may be needed if the respiratory (breathing) muscles are affected. Post-polio syndrome should be distinguished from similar symptoms which may be due to degenerative changes in the joints or soft tissues, peripheral nerve entrapment, or aging.

The current recommendation for patients with poliomyelitis is to avoid excessive use of affected muscles. Individuals should pace any physical activity, taking regular breaks. Not exerting to the point of pain or fatigue is very important. Adaptations around the home such as lowering shelves or sitting when washing dishes can be used to reduce the effect of day-to-day activities on the muscles.

In the most severely affected patients, all the limb and trunk muscles as well as the breathing and swallowing muscles may be affected and treatment with mechanical respiratory support is required to maintain life. The most common long-term effect is weakness of one or more limbs.

Inheritance patterns
Not applicable.

Prenatal diagnosis
Not applicable.

The British Polio Fellowship

Helpline: 0800 018 0586
Email: [email protected]
Website: britishpolio.org.uk

The Fellowship is a Registered Charity in England and Wales No. 1108335. It provides information, welfare and support to people in the UK living with the effects of Polio and Post Polio Syndrome (PPS). The Fellowship has groups and branches across the UK.

Group details last updated September 2014.

Pituitary conditions often develop very slowly and, in many cases, symptoms have been present for months or even years by the time a diagnosis is made. Once a pituitary condition is suspected, initial laboratory tests can be carried out either through a GP or an endocrinologist (specialist in endocrine disorders). The type of test performed is usually indicated by the presenting signs and symptoms. Radiological imaging, usually magnetic resonance imaging (MRI) is also commonly used to detect the presence of pituitary adenomas.

The most appropriate treatment depends on the tumour type. Prolactinomas are usually treated medically with drugs such as cabergoline, bromocriptine or quinagolide. These are effective in suppressing prolactin production and also shrink the pituitary tumour.

Patients with acromegaly, Cushing’s disease or non-functioning pituitary tumours usually require an operation to remove the pituitary mass. If this fails to cure the condition, radiotherapy may be considered. Additional treatment options include monthly injections in acromegaly and removal of the adrenal glands in Cushing’s disease.

Inheritance patterns
Pituitary disorders can affect any age group and, with the exception of certain familial syndromes (those that run in families), are not generally thought to be hereditary in origin.

Prenatal diagnosis
None.

The Pituitary Foundation

Patient Support and Information Helpline: 0117 370 1320
Email: [email protected]
Website: pituitary.org.uk

The Foundation is a Registered Charity in England and Wales No. 1058968. It provides information and support to anyone affected by pituitary conditions, including information specifically for young people. The Foundation runs a Patient and Family Support Helpline, and an Endocrine Nurse Helpline that offers access to a specialist nurse to provide expertise and medical advice. It has a network of local support groups across the UK and the Republic of Ireland, and a group that supports younger patients and their parents. 

Group details last reviewed December 2025.

The main symptoms of the condition are severe intellectual disability, breathing abnormalities with intermittent periods of overbreathing and breath holding, and characteristic facial features including a wide mouth, prominent lips and deep-set eyes. Individuals with Pitt Hopkins syndrome are often short compared to other family members and may have a smaller head size. Seizures (see entry Epilepsy) may be present and brain scans often show some specific abnormalities. There are minor differences in the shape of the fingers and slim feet, often with shorter fourth and fifth toes. Constipation may also be a problem. Speech is very limited in Pitt Hopkins syndrome, often to a few words. It has been noted that many people with Pitt Hopkins syndrome have a tendency to smile frequently and this characteristic, together with some unsteadiness on walking leads to the diagnosis often being confused with Angelman syndrome. The breathing abnormalities, sometimes associated with colour change, are not present in every person and may not appear until mid-childhood. This diagnosis is therefore often made relatively late. Another commonly described characteristic is shaking the head in a “figure of eight” movement.

Pitt Hopkins syndrome is caused by abnormalities of a gene called TCF4 on chromosome 18q21.2. The TCF4 gene controls the activity of many other genes and together with them plays an important part in how the brain develops and functions.

The diagnosis of Pitt Hopkins syndrome is often recognised by experienced doctors when they see and examine an affected individual, and can therefore sometimes be made without any tests. However, in most cases it will be confirmed by genetic testing of the TCF4 gene. The tests should look for both a single spelling mistake within the gene (point mutation) or for evidence that the TCF4 gene is partly or wholly missing (deletion) as either can cause Pitt Hopkins syndrome.

There is no specific treatment available for Pitt Hopkins syndrome at the present time. Children with the condition can acquire some skills, and many eventually learn to walk.

Inheritance patterns
Most cases are sporadic, meaning the gene change responsible for the condition usually occurs for the first time in the affected child.

Prenatal diagnosis
Prenatal diagnosis for this condition is possible if a gene change is identified and testing of parents and genetic counselling is recommended for families with an affected child, though risks of recurrence are low.

Pitt Hopkins UK

Email: [email protected]
Website: pitthopkins.org.uk

Pitt Hopkins UK are a Registered Charity No.1167153 and they provide up to date information and support for families with children with Pitt Hopkins Syndrome. They also offer a Facebook page, an online support group and a useful free app called Pitt Hopkins.

Group details last updated July 2016

There is no support group for Pierre Robin syndrome in the UK. The Cleft, Lip and Palate Association (CLAPA) may be able to link families (see entry Cleft Lip and/or Palate).

Families can use Contact’s freephone helpline for advice, information and, where possible, links to other families. To meet other families with disabled children, join Contact’s closed (private) Facebook group.

In the UK, infants with PKU are detected on newborn screening and commenced on treatment prior to the development of symptoms. Prior to screening being available, children would present with developmental concerns within the first year or so of life. This was associated with a mild odour, dry skin and reduced hair, skin and eye pigmentation in some patients.

The Guthrie test (heel prick test) is now done on all newborn babies at six to ten days of age and can identify PKU at an early age.

The diet of an affected child is carefully controlled so that only the small amount of phenylalanine necessary for growth is given. With a phenylalanine-restricted diet children with PKU develop normally. It is imperative that women with PKU should be on a low phenylalanine diet before or from early pregnancy to reduce the risk of fetal abnormality.

Inheritance patterns
Autosomal recessive. Genetic advice is available for families with the condition.

Prenatal diagnosis
May be made by genetic studies on chorionic villus samples in families already studied.

National Society for Phenylketonuria (NSPKU)

Helpline: 030 3040 1090
Email: [email protected]
Website: nspku.org

The Society is a Registered Charity in England and Wales No. 273670. It provides information and support to people with Phenylketonuria (PKU) and their families and carers. The Society promotes the care and treatment of PKUs and works closely with medical professionals. It organises events such as conferences and study days throughout the UK, and has a network of local support groups.

Group details last updated December 2014.

Information and support in the UK for metabolic diseases is also provided by Metabolic Support UK (see entry Inherited Metabolic diseases).

There is no support group for Peters anomaly or Peters Plus syndrome in the UK. Families can use Contact’s freephone helpline for advice, information and, where possible, links to other families. To meet other families with disabled children, join Contact’s closed (private) Facebook group.

Information and support in the UK for Perthes disease is provided by Steps (see entry Lower Limb Abnormalities).

Symptoms depend on which nerves are damaged. They often affect the feet and sometimes the legs and hands and include muscle weakness and abnormal feelings such as numbness and pins and needles. The abnormal feeling may be painful, like burning or pricking. Symptoms may also include clumsiness and tiredness. The condition may be very mild and cause no or little trouble. However, it can sometimes be severe, causing severe numbness, pain or weakness.

There are hundreds of causes of peripheral neuropathy. The most common cause is diabetes (see entry Diabetes Mellitus). About half of people with diabetes get peripheral neuropathy usually causing numbness and sometimes pain in the feet. This is more likely if the blood sugar control is poor. Other causes are:

• alcohol
• lack of particular vitamins
• poisons in the environment
• some drugs
• inflammation of the nerves
• hereditary (affecting more than one member of a family).

In about a quarter of people with peripheral neuropathy no cause is found.

A doctor will often be able to tell if a person has peripheral neuropathy by listening to their symptoms and doing an examination. If the cause is obvious, for instance in diabetes, the person may not need to see a specialist. If not, they should see a neurologist, (a specialist in diseases of the peripheral nerves and brain). The doctor may conduct blood and urine tests to find out what the cause is. They may also use the following special tests:

• an electromyography (EMG) – where the doctor gives small electrical shocks to the nerves to tell whether they conduct messages properly. This helps to tell whether peripheral neuropathy is present and what type it is.
• a lumbar puncture – where the doctor numbs the lower part of the back and then removes some the spinal fluid from inside the backbone with a needle. Examining the spinal fluid in the laboratory helps to tell what type of peripheral neuropathy is present.
• a nerve biopsy – this is rarely needed. After an injection of anaesthetic a doctor removes a tiny piece of nerve, usually from the outside of the ankle, to examine under the microscope. This helps to show the cause of the peripheral neuropathy.

The treatment needed will depend on the symptoms a person experiences. If it is weakness they may need:

• exercises prescribed by a physiotherapist.
• splints if their ankles are very weak
• one or two sticks or crutches or a frame to help walking
• very rarely, a wheelchair.

If it is loss of feeling they may need:

• to take great care of their feet to avoid ulcers.

If there is pain, they may be helped by:

• exercise
• drugs including paracetamol, amitriptyline or nortriptyline, gabapentin or pregabalin, carbamazepine, duloxetine or tramadol
• attending a special pain clinic for a pain management programme.

There are specific treatments for some types of neuropathy:

• diabetic neuropathy: good blood sugar control
• alcoholic neuropathy: not drinking anymore and vitamin B1
• vitamin-deficiency neuropathy: vitamin supplements. The missing vitamin needs to be identified by a doctor
• drug-related neuropathy: stopping the drug responsible
• inflammatory neuropathy: anti-inflammatory treatment with corticosteroids or other drugs
• hereditary neuropathy: no specific treatment is yet available.

Inheritance patterns
Some cases of peripheral neuropathy are hereditary. If a doctor or neurologist suspects this then they will refer the family to a genetics centre for information and support.

Prenatal diagnosis
Not applicable.

Families can use Contact’s freephone helpline for advice, information and, where possible, links to other families. To meet other families with disabled children, join Contact’s closed (private) Facebook group.

Children who are born with PS may begin to lose their hearing at birth or by the time they are three years old. The hearing loss is progressive, which means that a child will have less hearing over time and quite often is bilateral (meaning it affects both of the ears). Some individuals may become totally deaf (see entry Deafness). PS can affect the thyroid (a small gland in the front of the neck) by causing it to grow too large. An enlarged thyroid gland is known as a goiter.

Learning difficulties may occur in individuals with PS due to congenital thyroid defects. In a few rare cases, this may also increase the risk of thyroid cancer (see entry Cancer). PS also may affect the vestibular system, which controls balance and some individuals with PS will show some vestibular weakness when their balance system is tested.

PS is caused by changes, or mutations, to a gene known as SLC26A4 (also referred to as the PDS gene) on chromosome 7. The normal PDS gene makes a protein, called pendrin, which is found at significant levels in the thyroid gland only.

The diagnosing physician will assess a person’s hearing, inner ear structure and in some cases, the thyroid when diagnosing PS. They will look for two key characteristics of PS in the inner ear:

• a cochlea with too few turns. The cochlea is the spiral-shaped part of the inner ear that converts sound into electrical signals that are sent to the brain
• enlarged vestibular aqueduct. This is a bony canal that runs from the vestibule (a part of the inner ear between the cochlea and the semi-circular canals) to the inside of the skull.

There is no cure for PS. Children with PS should start early treatment to learn skills that will help them communicate with reduced hearing, such as how to use a hearing aid or learning sign language and cued speech. Some individuals with PS will develop a hearing loss significant enough to be considered eligible for a cochlear implant. This is an electronic device that is surgically inserted into the cochlea and helps a person develop a new way of understanding speech. If a goiter becomes large, a person may have problems breathing and swallowing. A specialist will monitor a person’s goiter over time and decide what treatment is necessary.

Inheritance patterns
PS is inherited as an autosomal recessive trait. Most affected individuals have no family history of PS. However, when the altered gene for PS is detected in an individual, genetic counselling should be sought to discuss testing for carriers of the mutation in families and prenatal testing for future pregnancies.

Prenatal diagnosis
Prenatal testing may be available for individuals with PS where the genetic mutation in a family has been identified.

There is no support group for Pendred syndrome in the UK. Information and support for deafness associated with Pendred syndrome is provided by deafness support organisations (see entry Deafness).

Families can use Contact’s freephone helpline for advice and information To meet other families with disabled children, join Contact’s closed (private) Facebook group.

PV causes the skin to separate easily and peel easily. For many individuals, PV usually begins with blistering in the mouth and throat. This may be followed by blistering or erosions of the skin, including the groin, underarm, face, scalp and chest areas. PV lesions may cover extensive portions of the body. In some affected people the lesions are relatively asymptomatic. However, in the healing stage following treatment, the lesions often crust over but they no longer itch or burn and leak fluid. In some people the skin lesions may itch and burn continuously and rupture which may leave red erosions of the skin surrounded by a crust and scaling. Affected areas usually heal without scarring, unless the lesions become infected. Blisters in the mouth may make it difficult to eat and drink, leading to problems with weight loss and dehydration.

PV is one of a group of chronic, relapsing conditions in which the immune system produces antibodies against specific proteins in the skin and mucous membrane, leading to the inability of the skin cells to bind together. It is thought that PV may be triggered by a range of factors. A few cases of PV have occurred following reactions to medications, including penicillamine and captopril. Individuals are probably genetically predisposed to PV. Specific information about a gene change(s) will not, however, indicate the certainty with which an individual will become affected with PV in the future.

Diagnosis of these diseases is made by skin biopsy (where a small amount of skin is removed for study in a laboratory) and immunopathology (analysis of body fluids to detect if there are any antibodies attacking the proteins in the skin and mucous membranes).

There is no cure available for PV, but in most cases available treatments are highly successful in reducing symptoms and preventing complications. PV is often initially controlled with high-dose steroids together with one of a number of so-called ‘steroid sparing’ immunosuppressive drugs. Response to medication varies from individual to individual and, for some people, lesions may not heal for extended periods of time. The main risk from PV is infection and complications resulting from medication aimed at suppressing the immune system. Consequently doses are kept as low as possible, consistent with controlling symptoms.

Inheritance patterns
None detectable but familial cases occur very rarely.

Prenatal diagnosis
None available and not appropriate.

Pemphigus Vulgaris Network

Helpline: 0208 863 3735
Website: pemphigus.org.uk

The Network is a support group for people living with Pemphigus and Mucous Membrane Pemphigoid. The helpline offers information and support to affected individuals, their families and carers, and medical professionals. 

Group details last updated October 2015.

Classical PMD − Type I – presents with delayed motor development in the first three years of life and nystagmus (shaking of the eyes). The difficulties with movement can include spasticity (stiff or rigid muscles), hypotonia (floppiness), choreoathetosis (extra movements) and ataxia (unsteadiness/loss of coordination). Slow progress is made to sitting or sometimes walking, and speech. This is followed by slow deterioration in the second decade of life. Congenital or Type II can begin in the first few months and runs a much more severe course than Type I, which may include epilepsy and a very limited life span. There is an intermediate Type III described and what is known as PMD-like disease.

The disorder is caused by a range of defects in PLP1 gene on chromosome Xq22 that controls proteolipid protein, an important constituent of myelin. This is not the case for PMD-like disease where different genes and inheritance are described.

Magnetic resonance imaging (MRI) scans can usually be used for diagnosis in the appropriate clinical setting.

Inheritance patterns
The main types of PMD (I,II,III) are inherited as X-linked recessive (boys only are affected and female relatives may be carriers). PMD-like disease appears to have a different genetic basis and may be autosomal recessive.

Prenatal diagnosis
Prenatal diagnosis is available to those that carry the PLP1 gene defects.

Information and support in the UK for metabolic diseases is provided by Metabolic Support UK (see entry Inherited Metabolic diseases).

Infants with PEHO syndrome may become increasingly floppy (hypotonia) and lose control of their muscles. The muscles supporting the head become floppy and weak and rolling over, sitting, standing and walking are rarely accomplished. Oedema or swelling of the hands, feet and face is also a feature of PEHO syndrome which may be transient or permanent.

Another feature of PEHO syndrome is the occurrence of infantile spasms. These are a distinctive type of epileptic seizure characterised by brief, but often repetitive, muscle contractions usually involving the head, trunk, and extremities. They occur in association with a particular pattern on EEG examination known as hypsarrhythmia. More typical seizures also occur in PEHO syndrome and may begin from birth to 12 months. Infants with PEHO syndrome gradually lose their ability to see (optic atrophy). Visual fixation is either absent at birth or lost during the first months of life, leaving infants with wandering and upward-turning eyes. Learning difficulties (see entry Learning Disability) have also been associated with PEHO syndrome. These become apparent at an early stage and usually affect language skills.

At birth, neonates are severely floppy, have feeding difficulties and are very drowsy. Their appearance is characterised by an expressionless, pear-shaped face with narrow forehead, broad, puffy cheeks and receding chin. The nose is small and upturned and the mouth is constantly open with a curved upper lip. Earlobes are outward turning. Although the head size is normal at birth, it usually becomes smaller (microcephaly) during the first year and the face becomes narrower with time.

The major diagnostic criteria for PEHO syndrome include changes in the brain, notably in the cerebellum (cerebellar atrophy) and progressing to the brain stem. This may be identified by magnetic resonance imaging (MRI) scan or at post-mortem. A diagnosis of PEHO-like syndrome may be given to those infants who look similar to infants with PEHO syndrome but who may have milder clinical features and fail to show the progressive cerebellar atrophy on brain MRI diagnostic of PEHO syndrome.

A number of conditions share similar features with PEHO syndrome including Joubert syndrome, autosomal recessive cerebellar hypoplasia, olivo-pontine cerebellar atrophies and carbohydrate-deficient glycoprotein (CDG) syndromes.

Inheritance patterns
PEHO syndrome is thought to be inherited as an autosomal recessive trait.

Prenatal diagnosis
None available.

Families can use Contact’s freephone helpline for advice and information To meet other families with disabled children, join Contact’s closed (private) Facebook group.