Proximal symphalangism
Proximal symphalangism (SYM1) is an autosomal dominant skeletal disorder. The hallmark feature is bony fusion across the finger joints. Other joints can also be affected, including those in the middle ear. This can lead to hearing loss. Intelligence, other organ systems, and life expectancy are not affected.
The gene responsible for SYM1 is called NOG. It maps to human chromosome 17q22. NOG encodes a secreted protein, called NOGGIN that inhibits a class of growth factors. A related disorder, multiple synostosis syndrome, type 1, is caused by a different change in the NOG gene. We are currently performing mutation detection on the NOG gene on a research basis. To the best of our knowledge, molecular testing is not clinically available. Physicians seeking assistance in making this diagnosis are welcome to contact us. Additional resources that may be of value are listed below.
We are currently seeking additional individuals and families with SYM1 to participate in our research. We would like to identify additional disease causing genetic changes and to correlate them with the specific pattern of joint involvement seen in the corresponding patient. These genotype/phenotype correlations will enable us to better understand how joints form. Blood samples with accompanying X-rays and clinical information from additional patients would be greatly appreciated.
We are currently seeking additional individuals and families with SYM1 to participate in our research. We would like to identify additional disease causing genetic changes and to correlate them with the specific pattern of joint involvement seen in the corresponding patient. These genotype/phenotype correlations will enable us to better understand how joints form. Blood samples with accompanying X-rays and clinical information from additional patients would be greatly appreciated.
If you are a patient, or have a patient with proximal symphalangism and are interested in participating in our research, please contact us. For sample submission instructions, click on How to submit samples. Have the participant sign our consent form.
If you are a patient or family member interested in communicating with other families, please email Dr Warman. Whenever new consenting family members contact us, emails (or phone numbers) will be exchanged. The Center for the Study of Genetic Bone and Joint Disorders does not monitor communications directly between families, and therefore cannot be responsible for the accuracy of information exchanged.
Additional information can be obtained through Online Mendelian Inheritance in Man, a database catalogue of human genes and genetic disorders edited by Victor A. McKusick and colleagues. The OMIM number for proximal symphalangism is 185800.
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