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Re: campomelic dysplasiaFrom: T-H Bui, Clinical Genetics, Karolinska Hospital (bui@gen.ks.se)Tue Sep 24 10:25:15 1996
At 08.54 1996-09-24 -0500, charlie chambers wrote: >Have a patient with prior child affected with campomelic dysplasia who is >now pregnant. No other affected relatives or suspicious family history. >Would appreciate any information regarding current genetic testing or modes >of inheritance. I can understand that one may be confused about the mode of inheritance in campolic dysplasia (also called camptomelic dysplasia). It has long been thought that it is an autosomal recessive disorder. However, evidence is accumulating that campomelic dysplasia (CMPD1) and autosomal XY sex reversal (SRA1) are caused by mutations in the SRY-related gene SOX9 located on 17q leading to haploinsufficiency for SOX9. Sex reversal (46,XY female) is found in about 2/3 of CMPD1. Recent evidence suggests (Nature genetics 13(2):230-2, 1996 June) that impairment of gonadal and skeletal development in these cases results, at least in part, from loss of transactivation of genes downstream of SOX9. Other mechanisms have been discussed also by Wirth et al. (Hum Genet 1996; 97:186-193). The mode of inheritance in CMPD1 is, based on molecular studies, autosomal dominant. Most cases should be sporadic due to de novo mutations. This is in agreement with formal genetic segregation analysis (Mansour et al. 1995; 32(6): 415-20). Thus, the recurrence risk for your patient should be very low (=new mutation risk). When recurrence has occured, the possibility of gonadal mosaicism should be strongly suspected. Because of the latter possibility, and possibly genetic heterogeneity, one should offer prenatal diagnosis by ultrasound. Phenotypic fetal sex (by U/S) should also be compared to karyotypic sex as a clue to diagnosis. If a mutation in SOX9 has been found in your index patient, this will make direct mutation analysis feasible prenatally in a new pregnancy. Was the index patient in your family sex reversed? Was the diagnosis of campomelic dysplasia made by a 'recognized authority' in skeletal dysplasia? ***************************************************************** The-Hung Bui, M.D. Associate Head Physician -- Department of Clinical Genetics Karolinska Hospital S-171 76 Stockholm, Sweden
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