Saethre-Chotzen syndrome with severe developmental delay associated with deletion of chromosomic region 7p15 --> pter.

Saethre-Chotzen syndrome represents one of the most common types of craniosynostosis inherited as an autosomal dominant disorder while sporadic cases have also been reported. It is characterized by high penetrance and variable expressivity, leading to difficulties in clinical diagnosis. Some patients, who exhibit most of the diagnostic criteria of Saethre-Chotzen syndrome, have structural abnormalities of chromosome 7. The case of a 4 year old boy with notable dysmorphic features compatible with Saethre-Chotzen syndrome and severe developmental delay is described. Conventional and molecular cytogenetic analysis of peripheral blood samples from the patient and his parents revealed partial monosomy of chromosomal region 7p15 --> pter de novo. The TWIST gene, located on chromosome 7p21.1, is thought to be a negative transcriptional regulator involved in osteoblast differentiation and maturation and it is thought that haploinsufficiency of the gene can cause the disorder. The diagnosis of Saethre-Chotzen syndrome and the identification of the chromosomal abnormality in the patient facilitated genetic counseling of the family.