• Register
  • Login
  • Bookmark this page!
Skip Navigation LinksHome Page    >    The various genetic diseases    >    Congenital diseases of the skeleton – general (previous name: “dwarfism”)
 
 
Pregnancy links...
Health links...
Genetics links...
Medical links...
Autism links...
Other links...
 
--%>

Congenital diseases of the skeleton - general (previous name: -dwarfism-)

Types

Congenital bone diseases are a diverse group of congenital disorders of bone growth, which eventually manifest in an extreme shortening of stature. In the past, these conditions were known as dwarfism - a term not used nowadays. The stunting of growth of the different parts of the body in these diseases is disproportionate, and this is the major clinical criterion for distinguishing these patients from people who are short for other reasons, such as growth hormone deficiency, etc.

There are more than 400 different types of congenital bone disease. They differ in many characteristics, such as:
  1. Age of onset - in some, the disease appears and is visible on ultrasound scans as early as the third trimester of pregnancy. In other types the age of onset is later and occurs at around the 30th week of pregnancy, and in yet other types there are no signs of growth problems until the age of two years.

  2. The inheritance pattern - in some, inheritance is autosomal dominant, in others autosomal recessive or X-linked.

  3. The parts of the body affected differ in the different diseases. Some involve the limbs, others just the trunk, and there are also different combinations of disproportionate shortening of different parts of the body.

  4. The severity of the bone involvement - in some types the disease is incompatible with postnatal life due to a very small chest and resultant respiratory distress, whereas other types are milder, with some types being so mild that only an expert in congenital bone diseases can identify them.

  5. Apart from this, the different types are differentiated by the type of changes seen on X-ray, metabolic changes and the different genes responsible for the diseases.

A number of common types of bone diseases are presented below - each has a separate information sheet

Clinical signs

As mentioned, there are hundreds of different types of congenital bone diseases that cause very short stature and disproportionate development of the structure of the various bones.

They differ by the characteristics described above under -types-.

The exact type can be diagnosed in a genetic institute, and once this has been determined, the inheritance pattern, the risk of recurrence, methods of investigation, diagnosis and preventive measures can be established.

Concerning all the sections below the following must be remembered:

A precise diagnosis is important, and a diagnosis made in the past may not always have been made according to today-s standards and methods and is not always accurate by today-s standards. Because of this, the diagnosis must always be confirmed in a genetic institute by examining the patient, or at least by looking at the clinical picture, photographs, X-rays and other data.

Even though we know a lot about the inheritance patterns, the risk of recurrence, the mechanism of the manifestations of the disease, etc., most of these diseases have exceptions, and each case/family must be examined individually in a genetic institute.

Inheritance pattern

All patterns of inheritance are possible - each case must be assessed individually depending on the specific disorder and distribution of cases in the family.

Penetrance

Depends on the specific type.

Associated features that can be demonstrated in tests performed during pregnancy

This depends on the age of onset and on the manifestation of short stature in the parents. The condition cannot be detected by ultrasound examination in pregnancy in those cases where the onset of the bone shortening is late, i.e. after birth or after the age of two years.

In all these cases it is important to refer the couple for genetic counseling, to which they should bring all data, including the results of other tests performed during the pregnancy such as alpha-fetoprotein, nuchal translucency, etc.

What is the risk of recurrence in a subsequent pregnancy?

In all these conditions, the risk of recurrence depends on the specific type of disease, the inheritance pattern, and the relationship to the patient, in accordance with the laws of inheritance.

The risk for more distant relatives depends on the number of affected individuals in the family, the degree of relationship between the relatives and the affected individuals, consanguinity between the parents, if present, etc. This risk is established within genetic counseling.

Molecular genetic information

The gene for the disease

Depends on the specific type.

Genetic testing

Diagnostic testing

Depends on the specific type.

Carrier testing

In families in whom the mutation has been found in the gene responsible for the disease, other family members can be examined for carrier status. There are no tests for carrier status in the healthy population.

Fetal testing

Usually the same as diagnostic testing.
 
Haven't found what you're looking for? Search for it here:   
Comments (0)





Leave a Comment
Name
Email (will not be published)
Website (optional)
Subject
Your Comment

Line and paragraph breaks are automatic.

Please type the characters you see in the picture:


All content Copyright © 2009-2011, Genetics of Pregnancy Encyclopedia Corporation. All rights reserved.