Condition AZ: u

If your child is affected by a medical condition or disability we can help. Call our freephone helpline on 0808 808 3555 to get information, support and advice. You can also browse our range of parent guides on aspects of caring for a disabled child in our resource library.

To meet other parents see support groups below or meet other parents online in our closed Facebook group

Please see below for reliable medical information on Uveitis produced by alternative providers.

NHS website
www.nhs.uk/conditions

Although alternative links have been selected with great care, Contact  cannot accept responsibility for any inaccuracies or errors. Alternative information providers give details of their quality control procedures on their website, which includes review of information by a qualified medical professional.

Is there support?

Olivia’s Vision

Email: contact@oliviasvision.org
Website: oliviasvision.org

The Organisation is a Registered Charity in England and Wales No. 1138599. It provides information and support to anyone affected by uveitis, including childhood uveitis.

Group details last reviewed December 2021.

Background

Usher syndrome is a genetic condition that causes sensory neural hearing loss and retinosis pigmentosa (RP). Sensory neural hearing loss occurs because the sensitive hair cells inside the ear are damaged. Children and adults affected by Usher syndrome are usually totally (type 1) or partially (type 2) deaf from birth (known as congenital deafness).

The early symptoms of RP include difficulty seeing in the dark and in different lighting conditions. Over time, vision gradually deteriorates until tunnel vision develops and people cannot see objects unless they are directly in front of them. Reduced vision may not occur until adolescence or early adulthood. In some people, poor balance is an associated problem.

Credits

Medical text written November 1991 by Contact a Family. Approved November 1991 by Professor M Patton, Professor of Medical Genetics, St Georges Hospital Medical School, London, UK and Dr J E Wraith, Consultant Paediatrician, Royal Manchester Children’s Hospital, Manchester, UK. Last updated July 2012 by Dr Maria Bitner-Glindzicz, Clinical and Molecular Genetics Unit, Institute of Child Health, London, UK.

What are the symptoms?

There are three types of the syndrome:

  • type I is characterised by profound congenital hearing loss, poor balance and RP usually around the age of ten years
  • type II presents moderate to severe congenital hearing loss, normal balance and RP develops in the late teens or early 20s
  • type III is characterised by progressive hearing loss often in childhood and RP progressing at a variable rate, generally with onset around the second or third decade of life.

What are the causes?

Usher syndrome is an inherited genetic condition caused by changes in DNA (mutations) in certain genes. The genes related to Usher syndrome play a role in the development and maintenance of hair cells which are important for transmitting sound in the ear and determining the structure and function of light-sensing cells, called rods and cones, in the eye.

Type I can result from mutations in the CDH23, MYO7A, PCDH15, USH1C or USH1G genes. Other unidentified genes also cause type 1 Usher syndrome. Type II is caused by mutations in at least four genes. Only three of these genes, USH2A, GPR98 (also called VLGR1) and DFNB31 have been identified. Mutations in at least two genes are responsible for Usher syndrome type III, however, CLRN1 is the only gene that has been identified.

How is it diagnosed?

Children with profound hearing loss and delayed motor milestones should be considered ‘at risk’ of having Usher syndrome type 1. Diagnosis of Usher syndrome type 1 in a deaf child may occur using an electroretinogram (ERG) at a time when the child has no visual problems. An ERG measures the electrical response of the eye’s light-sensitive photoreceptor cells (rods and cones). Electrodes are placed on the cornea and the skin near the eye to measure the electrical currents coming from the cells when a light is flashed. More often, diagnosis may be delayed until the visual problems have become significant.

How is it treated?

Although there is no treatment available for Usher at the moment, many people with Usher have adjusted very successfully to their condition. Children with Type 1 Usher syndrome usually benefit from cochlear implantation. A cochlear implant is a small, electronic device that can help to provide a sense of sound to a person who is deaf. It consists of an external portion that sits behind the ear and a second portion that is surgically placed under the skin. The implant does not restore normal hearing. Instead, it can give a deaf person a useful representation of sounds in the environment and help him or her to understand speech.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
The genetic changes causing Usher syndrome are inherited in an autosomal recessive manner. Genetic advice should be sought by affected families.

Prenatal diagnosis
Several genes have been identified which in theory, allow prenatal diagnosis. However, genetic testing is difficult due to the number and size of the genes which have to be screened. Prenatal diagnosis can only be offered where the genetic mutation that causes Usher syndrome in a family is known.

Is there support?

Usher Kids UK

Email: info@usherkidsuk.com
Website: usherkidsuk.com

Usher Kids UK has been set up to support, inform, connect and advocate for children with Usher syndrome and their families. The group provides a quarterly newsletter and is planning to hold family events. They also aim to raise awareness and help to educate professionals about the condition.

Group details added June 2018

Information and support for Usher Syndrome is also provided by Sense (see Deafblindness).

Background

In humans, protein rich foods are broken down to make energy for our bodies. After the energy is used up, waste substances like nitrogen are created. In the body, excess nitrogen in the form of ammonia (which is toxic in high levels) is converted to urea via the urea cycle. Urea is then simply cleared in the urine. The urea cycle disorders (UCDs) are a group of metabolic diseases where the urea cycle is unable to operate correctly. Ammonia levels can then build up, which causes certain symptoms. They are usually noticed in the first month of life, but symptoms may start at almost any age.

Credits

Last updated June 2014 by Dr M Champion, Consultant in Paediatric Inherited Metabolic Disease, Evelina London Children’s Hospital, London, UK.

What are the symptoms?

High ammonia levels in the blood and brain cause irritability, poor feeding, vomiting, drowsiness and, in severe cases, coma.

The most common symptom of arginase deficiency is the neurological disorder spastic diplegia, where there is an abnormal increase in muscle tension and the muscles are tight and stiff. Developmental delay may also occur.

What are the causes?

The urea cycle has several steps, each catalysed (driven) by a different enzyme. UCDs occur when there is a deficiency (low levels or complete absence) of one of these enzymes:

  • N-acetyl glutamate synthase (NAGS) deficiency
  • carbamyl phosphate synthase (CPS) deficiency
  • ornithine transcarbamylase (OTC) deficiency
  • citrullinaemia (argininosuccinate synthase deficiency)
  • argininosuccinic aciduria (argininosuccinate lyase deficiency)
  • arginase deficiency

The most common UCD is OTC deficiency.

Each condition results from a fault (mutation) in the gene that codes for the enzyme involved.

N-acetyl glutamate synthase (NAGS) deficiency

NAGS gene

carbamyl phosphate synthase (CPS) deficiency

CPS1 gene

ornithine transcarbamylase (OTC) deficiency

OTC gene

citrullinaemia (argininosuccinate synthase deficiency)          

ASS1 gene

argininosuccinic aciduria (argininosuccinate lyase deficiency)

ASL gene

arginase deficiency           

ARG1 gene

How is it diagnosed?

The diagnosis of a UCD requires tests on blood to look at ammonia levels, the pattern of the building blocks of protein (amino acids) and a urine test (organic acids) to look for substances found in UCDs.

The diagnosis is then confirmed on either an enzyme test to prove that the enzyme is not fully working or a gene test to identify where the fault in the gene has occurred.

How is it treated?

The main aim of treatment is to keep the level of ammonia in the blood at a safe level. UCDs are usually treated with a low protein diet and medicines such as sodium phenylbutyrate, sodium benzoate or carbamylglutamate. Arginine or citrulline may be supplemented to help the urea cycle work harder in removing the ammonia.

Infections or a sudden increase in the amount of protein eaten can cause blood ammonia levels to rise. During periods of infection, protein intake is stopped, and special high energy drinks are given (glucose polymer) or glucose is given intravenously (in a vein). If levels of ammonia are very high, dialysis may be used to control and bring down levels down more quickly.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
Mutation in CPS1, ASS1, ASL, NAGS, and ARG are inherited in an autosomal recessive manner. OTC deficiency is inherited in an X-linked manner.

Prenatal diagnosis
Prenatal diagnosis is available for all the conditions, if the mutation in the family is known. Affected families should seek genetic advice.

Is there support?

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

If your child is affected by a medical condition or disability we can help. Call our freephone helpline on 0808 808 3555 to get information, support and advice. You can also browse our range of parent guides on aspects of caring for a disabled child in our resource library.

To meet other parents see support groups below or meet other parents online in our closed Facebook group

We no longer hold a description of Upper Limb Abnormalities. You may find it more helpful to search for a particular or specific condition in our online medical information instead.

Other UK sites with trusted health information:

NHS Choices
www.nhs.uk

Patient UK
www.patient.co.uk

Although alternative links have been selected with great care, Contact a Family cannot accept responsibility for any inaccuracies or errors. Alternative information providers comply with the Information Standard and give details of their quality control procedures on their website, which includes review of information by a qualified medical professional.

Is there support?

Reach

Tel: 0845 130 6225
Email: via website
Website: reach.org.uk

Reach is a Registered Charity in England and Wales No. 1134544. It provides information and support to children affected by upper limb difference, and their families. The Charity offers a network of local branches across the UK. 

Group details last updated December 2014.

If your child is undiagnosed we can help. Call our freephone helpline on 0808 808 3555 to get information, support and advice. You can also browse our range of parent guides on aspects of caring for a disabled child in our resource library, or take a look at our new section ‘Is your child without a diagnosis?

To meet other parents see support groups below or meet other parents online in our closed Facebook group

Other UK sites with trusted health information:

NHS Choices
www.nhs.uk

Patient UK
www.patient.co.uk

Although alternative links have been selected with great care, Contact a Family cannot accept responsibility for any inaccuracies or errors. Alternative information providers comply with the Information Standard and give details of their quality control procedures on their website, which includes review of information by a qualified medical professional.

Is there support?

SWAN UK

Tel: 020 7831 0883
Email: via website
Website: undiagnosed.org.uk

SWAN UK (Syndromes Without A Name) is an initiative run by the charity Genetic Alliance UK to provide information and support to families of children with undiagnosed genetic conditions. It offers an online forum, family fun days and local meet ups, and works with healthcare and other professionals to highlight the challenges faced by families of children with undiagnosed genetic conditions.

Group details last updated January 2017.