Condition AZ: n

Nystagmus is not painful. Problems resulting from congenital or early onset nystagmus tend to improve until vision stabilizes around the age of five or six years of age.

Congenital nystagmus can be caused by either a problem with the eye itself or with a problem with the visual pathway from the eye to the brain. All children are born with a visual system that is not fully developed. This vision continues to develop in the first few years of life as a result of the eye and brain being stimulated by what we see. If a child is born with an eye condition which affects vision such as cataracts, glaucoma, some conditions of the retina or albinism then their visual system may not develop normally.

Children who have learning disabilities, such as Down syndrome, may also develop nystagmus. Nystagmus can also be caused by some inherited neurological conditions.

Because nystagmus may be the first sign of a problem of the eye or the brain, it is vital that when it first develops the child is referred to an ophthalmologist (eye specialist) or a neurologist. Occasionally no visual condition can be detected and the nystagmus is termed congenital idiopathic nystagmus or congenital motor nystagmus.

Management of nystagmus in children involves giving them plenty of stimulation in the early years to help them make best use of the vision they have. It is very likely that an ophthalmology clinic will monitor the condition and this may mean seeing a number of different professionals, such as an ophthalmologist (specialist eye doctor), an orthoptist (specialist in eye movements), and an optometrist (specialist in carrying out assessments for low vision). Children should have a vision assessment and access to aids that will help with low vision. Treatment for any underlying eye condition, such as glaucoma will also be necessary. Most children with the condition attend mainstream school with the right support.

Inheritance patterns
These depend upon the underlying visual disorder. Congenital idiopathic nystagmus may also be inherited. Affected families should be referred to a genetics centre for information and support.

Prenatal diagnosis
None.

Nystagmus Network

Helpline: 0845 634 2630
Email: info@nystagmusnet.org
Website: nystagmusnet.org

The Network is a Registered Charity in England and Wales No. 803440. It provides information and support for people with nystagmus, and their families and professionals. The Network holds events and funds research.

Group details last updated February 2016.

Norrie disease causes abnormal development of the blood vessels and tissues at the backs of the eyes, leading to retina detachments.

• The irises appear white when light is shone on them;
• Cataracts often develop;
• The irises and entire eyeball may shrink during the first few months of life, causing profound visual impairment.

Visual impairment of any cause can create developmental challenges in some individuals which may result in developmental delay, which can lead to learning disability (see entry Learning Disability) or behavioural issues.

Progressive sensorineural hearing loss (hearing loss of nerve origin) is a secondary symptom and in many patients can start in early childhood.

Norrie disease has been associated with peripheral venous insufficiency where the flow of blood through the veins is inadequate, causing blood to pool in the legs. Varicose veins and leg ulcers can develop.

Norrie disease has also been associated with short stature, delayed or arrested puberty, and sexual dysfunction. To date, the pathophysiological basis underlying the growth and pubertal issues remains largely unknown.

Some children and young people with Norrie are reported to have low muscle tone and joint hypermobility. Advice should be sought from Occupational therapy or physiotherapy support should there be functional difficulties.

It is an X-linked recessive condition, caused by a mutation of the NDP gene on the X-chromosome. A recessive condition is a condition where two copies of each chromosome need to be present for the disease to occur. However, as Norrie is an X-linked condition, it would occur in every boy born with a faulty X-chromosome. Norrie disease therefore usually occurs in boys, because boys only have one X-chromosome. A girl with one abnormal X-chromosome will be a carrier but will not be affected if the other X-chromosome does not have the abnormal gene. Carrier females have a 50% chance of passing the gene unto the unborn male.

Norrie disease is diagnosed on the basis of clinical eye findings if the individual presents with congenital blindness. Clinical genetic testing is available to help confirm the diagnosis.

The management of Norrie disease is targeted towards establishing the extent of the disease. This determines the needs of the individual and is likely to require the coordinated efforts of a team of specialists:

Ophthalmologists examine the eyes and decide on appropriate treatment.

Clinical Geneticists establish the genetic origin of the disease and to provide genetic counselling to the family.

Paediatricians assess development in early childhood and to coordinate medical care and educational support as required.

Audiologists carry out regular hearing tests and to advise on hearing aids or cochlear implants if required.

Endocrinologists ensure that any growth and pubertal issues are dealt with promptly, and growth of children and young people with Norrie disease is optimised. Growth must be monitored carefully by the local team, and children must be referred to a paediatric endocrinologist if there are concerns with respect to growth, and certainly, all children must be referred by the age of 11-12 years so that puberty can be monitored carefully.

Therapy support from Speech and Language Therapists, Occupational Therapists, Physiotherapists.

Specialist Education Support will be required with key professionals being:

• Rehabilitation Officer for sensory impairment
• Qualified Teacher of the visually impaired
• Qualified Teacher for the hearing impaired

 Other healthcare professionals may also be needed to systematically and comprehensively plan the treatment and management of the condition on a case by case basis.

Inheritance patterns

Norrie disease is caused by a genetic misprint (mutation) in the ND pseudoglioma (NDP) gene which is located on the X-chromosome. Norrie disease is passed on in families in an X-linked recessive pattern of inheritance.

Females (XX) have two copies of the NDP gene, one on each of their two X-chromosomes. Males (XY) have only one copy on their single X-chromosome. Norrie disease occurs in males when there is a misprint in their single copy of the NDP gene. Otherwise healthy females can carry an altered NDP gene with the working copy on their other X-chromosome usually being enough to compensate for this, preventing them from developing the condition. The vast majority of mothers of a boy with Norrie disease are carriers of the condition.

Women who are carriers of Norrie disease have a 1 in 2 (50%) chance of passing the condition on to each son they have. Each of their daughters has a 1 in 2 (50%) chance of being a carrier of the condition. When a man with Norrie disease has children he will pass on his X-chromosome to all his daughters and so all (100%) daughters will be carriers of Norrie disease. None of the sons of a father with Norrie disease will inherit the condition from him as they will get their single X- chromosome from their mother.

Very occasionally Norrie disease can occur due to a new spontaneous (de novo) mutation, without the mother actually being a carrier of the condition. If the mother has had carrier testing for Norrie disease and has not been found to be a carrier then the chance of her having another child with a Norrie gene alteration is low but still slightly higher than that of the general population. This is because of the very small possibility of there being a few egg cells in her ovaries that have a Norrie gene alteration (a situation known as germline mosaicism).

 Prenatal diagnosis

Genetic testing methods change over time. A genetic doctor from an NHS genetic clinic can arrange testing of the NDP gene where appropriate, review the inheritance pattern and provide up-to-date management advice. Families are welcome to seek advice at various times of life from the genetic service or paediatrician. For example, when a child growing up with Norrie disease or their siblings want more details, they could attend the genetic clinic to ask about the condition for themselves.

The Norrie Disease Foundation

Email: enquiries@norriedisease.org.uk
Website: norriedisease.org.uk

The Norrie Disease Foundation is a Registered Charity No. 1171274. The Foundation aims to raise awareness of the condition, promote research and to strengthen the Norrie network. They provide information for families and medical professionals.

Group details reviewed December 2018.

Characteristics of Noonan syndrome include:

• heart defects – the most common being pulmonary valve stenosis, atrial septal defects (see entry Heart Defects) and hypertrophic cardiomyopathy (see entry Cardiomyopathies)
• characteristic facial features, including ptosis (drooping eyelids), hypertelorism (widely spaced eyes), large downward-slanting eyes, flat nasal bridge and short neck with neck webbing and anterior rotation (slanting forwards) of the ears
• short stature.

Additional features may include:

• excess oedema (fluid retention in the body) at birth and slow weight gain
• feeding difficulties with poor sucking and weaning and frequent and/or forceful vomiting in babies which may be assessed as failure to thrive
• mild hearing loss
• dental delay
• elevated or depressed sternum
• hypotonia
• undescended testes (meaning that the testicles stay within the abdomen)
• mild developmental delay in a small number of children
• speech and behaviour problems.

In addition, the characteristics of the syndrome, especially facial, appear to change as the individual ages.

Overlapping syndromes
LEOPARD syndrome, CFC syndrome (see entry cardiofaciocutaneous syndrome), Costello syndrome and neurofibromatosis are all due to defects in the same pathway and have different clinical features. However LEOPARD syndrome is the most similar and due to changes in the same gene PTPN11.

The term LEOPARD syndrome stands for:

• Lentignes (freckles)
• Electrocardiogram (minor abnormalities in the electrical activity of the heart)
• Ocular hypertelorism (widely spaced eyes)
• Pulmonary stenosis
• Abnormalities of the male genitalia
• Retardation of growth
• Deafness.

Inheritance patterns
Autosomal dominant. A gene PTPN11 on chromosome 12 has been found to account for half of all cases of Noonan syndrome. Other genes that may cause Noonan syndrome include SOS1, KRAS and SHOC2. Molecular testing is now available.

Prenatal diagnosis
Prenatal diagnosis is available by molecular testing if the mutation has been identified. Occasionally it may be diagnosed by the presence of cystic hygroma or fetal hydrops in the womb (where fluid accumulates in certain parts of the unborn baby).

Noonan Syndrome Association

Email: info@noonansyndrome.org.uk
Website: noonansyndrome.org.uk

Noonan Syndrome Association (NSA) is a Registered Charity in England and Wales No. 1140671. The NSA supports patients and families affected by Noonan Syndrome through research, nurse services, national and regional events, publications and raising awareness of the condition.

Group details last updated August 2021.

Mutations in the SMPD1 gene cause Niemann-Pick disease types A and B. This gene provides instructions for producing an enzyme called acid sphingomyelinase (ASM). Mutations in either the NPC1 or NPC2 gene cause Niemann-Pick disease type C. The NPC1 gene provides instructions for producing a protein that is involved in the movement of cholesterol and lipids within cells.

Type A and B are diagnosed by measuring the amount of ASM in white blood cells using a blood sample. Testing the DNA to look for the mutation causing types A and B can confirm the diagnosis.

A skin biopsy is usually used to diagnose type C and type D Niemann-Pick disease. Laboratory scientists will watch how the skin cells grow and study how they move and store cholesterol. Testing the DNA to look for the mutation causing type C/D can confirm the diagnosis.

At this time, there is no effective treatment for type A. But supportive therapies can be used to keep the child comfortable and improve their quality of life.

Bone marrow transplantation has been performed on a few patients with type B with fairly good results. Researchers continue to study possible treatments, including enzyme replacement therapy. Trials in humans are now underway in a number of countries, including the UK and USA.

Recently a new treatment called miglustat has been approved for type C. However, medicines are available to control or relieve many symptoms, such as cataplexy and seizures.

There is no specific treatment for type D.

Inheritance patterns
Autosomal recessive pattern of inheritance. Affected families should be referred to a genetic centre for information and support.

Prenatal diagnosis
For types A, B and most forms of type C, this is possible by chorionic villus sampling at ten to twelve weeks or amniocentesis at sixteen weeks.

Niemann-Pick Disease Group (UK)

Helpline: 0191 415 0693
Email: info@npuk.org
Website: npuk.org

The Group is a Registered Charity in England and Wales No. 1144406. It provides information and support to families affected by all forms of Niemann-Pick disease. It operates a 24 hour telephone helpline and funds a dedicated Clinical Nurse Specialist to give support through advice, counselling, specialist clinics and advocacy. Holds an annual family conference.

Group details last updated October 2015.

Support and information in the UK for metabolic disorders is also available from Climb (see entry Inherited Metabolic diseases).

Support for dementia in Niemann-Pick disease can be obtained from the Alzheimer’s Society (see entry Alexander disease).

In SCN frequent infections can develop very rapidly due to the impaired ability of children to combat them. Infections include:

• mouth ulcers and gingivitis (inflammation of the gums);
• sore throat
• chest infections
• diarrhoea
• burning sensation when urinating
• unusual redness, pain, or swelling around a wound
• high fevers and chills
• exhaustion and lethargy.

The cause of SCN differs according to the specific type and can be hereditary, autoimmune (in which the body destroys its own neutrophils), related to bone marrow production or idiopathic (of unknown cause).

Diagnosis of the different types of SCN is made by blood tests and bone marrow aspiration and biopsy (examination).

Granulocyte Colony Stimulating Factor (G-CSF) is used in the management of SCN and can significantly improve the quality of life by stimulating the bone marrow to produce neutrophils to fight infections. G-CSFs are given by an injection just under the skin using a very small needle. To make this less painful, a local-anaesthetic cream can be applied to the site half an hour before the injection is due. Prophylactic antibiotics may be given in addition, or are often effective alone for less severely affected individuals.

Inheritance patterns
Congenital neutropenia is typically sporadic but autosomal dominant and recessive cases are also described. Cyclical neutropenia is typically autosomal dominant but can be sporadic (with no other affected family members).

Prenatal diagnosis
This is theoretically possible if a causative mutation is identified. It is usual to find a mutation in around 60 to 70 per cent of cases of severe congenital neutropenia and cyclical neutropenia.

There is no support group for Neutropenia (Severe Chronic) 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.

Nerve Tumours UK

Tel: 020 8439 1234
Helpline: 07939 046030
Email: info@nervetumours.org.uk
Website: nervetumours.org.uk

Nerve Tumours UK is a Registered Charity in England and Wales No. 1078790. It provides information and support to those affected by Neurofibromatosis and Schwannomatosis. They have a network of specialist advisors based in hospitals around the UK.

Group details last reviewed June 2023.

Childhood Tumour Trust

Email: info@childhoodtumourtrust.org.uk
Website: childhoodtumourtrust.org.uk

The Trust is a Registered Charity in England and Wales No.1165777. They provide opportunities for children and young people with Neurofibromatosis 1 to attend camps in the UK and USA, raise awareness, campaign for better care and organise family days out.

Group details last reviewed June 2023.

Initial symptoms often include loss of appetite, tiredness and pain in the bones. Other symptoms vary, depending on where the child’s neuroblastoma starts:

• if the tumour is in the abdomen, the tummy may be swollen and there may constipation or difficulty passing urine. In some cases, the child’s blood pressure is high
• if the tumour affects the chest area, the child may be breathless and have difficulty swallowing
• if the tumour occurs in the neck, it is often visible as a lump and may affect breathing and swallowing occasionally, there are deposits of neuroblastoma in the skin that appear as small, blue-coloured lumps
• if the tumour is pressing on the spinal cord, children may have weakness in the legs and walk unsteadily. If the child is not yet walking, reduced leg movements may be noted. The child may also have constipation or difficulty passing urine
• very rarely, children may have jerky eye and muscle movements, and general unsteadiness associated with the neuroblastoma.

Tumours occur when the genes in cells that instruct them to grow and multiply in an orderly and controlled way have a mutation. In these cancerous cells, the change in these instructions causes the cells multiply uncontrollably forming a tumour.

A variety of tests and investigations may be needed to diagnose a neuroblastoma. A urine test for vanillylmandelic acid (VMA), or homovanillic acid (HVA) can be carried out in children suspected of having a neuroblastoma as the presence of VMA or HVA is indicative of the disease. mIBG (meta-iodo-benzyl guanidine) scanning can be used to visualise tumours. mIBG is readily taken up by a neuroblastoma and when a small amount of radioactive iodine is attached it enables tumours to be seen by a radiation scanner. A biopsy (removal of a small section of the tumour for further study) will allow the biology of the tumour to be analysed.

The treatment of neuroblastoma depends on the age of the child, the size and position of the tumour and whether the neuroblastoma has spread from its original location.

Surgery
Is used for tumours that have not spread (localised tumours) to remove the tumour. If the tumour is, at first, too large or in too difficult a position to remove safely, then chemotherapy will be given to shrink it before surgery.

Chemotherapy
Is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. A combination of different drugs is used. If the neuroblastoma has spread to several parts of the body, or is ‘high risk’ high dose chemotherapy may be used.

Radiotherapy
This uses high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells.

Retinoic acid therapy
This is given at the end of therapy for high-risk neuroblastoma. Retinoic acid is a drug similar to vitamin A that is given by mouth. It is a fairly safe drug but may cause skin rashes.

Antibody therapy
This uses antibodies to treat high-risk neuroblastoma. Antibodies are proteins that we all produce to fight infections. In this type of therapy, antibodies have been designed to attack neuroblastoma cells.

Inheritance patterns
None.

Prenatal diagnosis
None.

Neuroblastoma Society

Tel: 020 8940 4353
Email: info@neuroblastoma.org.uk
Website: neuroblastoma.org.uk

The Society is a Registered Charity in England and Wales No. 326385. It provides information and support to families with children affected by neuroblastoma, and gives them the opportunity to talk to other families. The Society raises funds for medical research into improving both diagnosis and treatment of the disease.

Group details last updated August 2014.

At or soon after birth most infants with Netherton syndrome look ‘scalded’. The skin is ‘leaky’ causing infants to lose heat, water and proteins, all of which are necessary for normal growth and development. For the most severely affected infants, the prognosis of Netherton syndrome is poor and, despite improved management of these babies, there remains a risk that the baby may not survive beyond the first six months of life. Most suffer from severe failure to thrive in the first year. The defective skin makes these babies at a higher risk of infection.

Later in childhood, some develop a distinctive circular scaling on the skin known as ichthyosis linearis circumflexa. The skin condition tends to go through bouts of flaring and may be itchy, sensitive or raw and often thickened at the joints. Individuals may become distressed if the skin, especially the face, is constantly red and peeling. Between episodes, the skin may appear relatively normal. In Netherton syndrome, the hair breaks easily making it look spiky on the scalp, but microscopic hair changes are also seen on the eyelashes, eyebrows and body hair. Individuals with Netherton syndrome have a higher risk of allergies and anaphylaxis. Some individuals are allergic to foods such as fish and nuts or are prone to hay fever, asthma and eczema-like rashes. Children with Netherton syndrome have high levels of IgE (an allergy antibody) in their blood and suffer attacks of agioedema (allergy-induced swelling). Individuals with Netherton syndrome are usually shorter than average and may have difficulty gaining weight. Gastrointestinal problems, such as diarrhoea, occur often, especially in early infancy.

This is a genetic disorder caused by the lack of a specific protein called LEKTI (lympho-epithelial kazal type related inhibitor), which is a serine protease inhibitor. The absence of this protein leads to a profound defect in the outermost part of the skin, ‘the skin barrier’.

The diagnosis is based on clinical features, a skin biopsy (where a small amount of skin is removed for analysis) to show microscopic features in keeping with Netherton syndrome, an antibody test on the skin sample demonstrating the absence of LEKTI and molecular genetic studies on blood DNA confirming the presence of the genetic mutation in the gene responsible for the LEKTI protein.

The main issue is the integrity of the skin barrier which can be improved by the regular, two-to-four-times daily, application of a greasy ointment-based moisturiser. In most children, the skin has a tendency to improve with age, although the basic problem persists.

There is no specific treatment as yet available. Research is actively exploring ways of replacing the missing protein in the skin. There are various potential methods including a topical ointment containing the protein, gene therapy or from stem cell research. A specific treatment is still some way off but undoubtedly achievable in time.

Inheritance patterns
Netherton syndrome is inherited as an autosomal recessive trait. The gene, which is defective in this condition, is called SPINK5 and is located on chromosome 5.

Prenatal diagnosis
This is available using molecular genetic analysis.

Information and support in the UK for Netherton syndrome is provided by the Ichthyosis Support Group (see entry Ichthyosis).

NeST – Nephrotic Syndrome Trust

Tel:  01935 706042
Email: info@nstrust.co.uk
Website: nstrust.co.uk

NeST is a Registered Charity in England and Wales no.1107601. They provide information and support to families and individuals affected by nephrotic syndrome. They aim to increase awareness of the condition and also fund research.

Group details reviewed June 2023.