Interstitial deletion of chromosome 9, int del(9)(9q22.31-q31.2), including the genes causing multiple basal cell nevus syndrome and Robinow/brachydactyly 1 syndrome
We report a child with a de novo interstitial deletion, 46,XY, int del(9)(9q22.31-q31.2). Cytogenetic and molecular analysis defined the boundaries of the lost region, of paternal origin, from D9S1796 to D9S938. The clinical picture included macrocephaly, frontal bossing, bilateral epicanthus, down-slanted palpebral fissures, low-set ears, hypoplastic nostrils, micrognathia, scoliosis, right single palmar crease, small nails, slender fingers, bilaterally flexed 5th finger, delayed bone age, abnormal metacarpophalangeal pattern (MCPP) profile and sole pits. No major malformation was recorded. The deleted region includes, among others, the PTCH and ROR2 genes. Mutations of the former cause the nevoid basal cell carcinoma syndrome (NBCCS) while mutations in the ROR2 gene have been found both in Robinow syndrome and in brachydactyly type 1B (BDB1). As the patient shows some clinical manifestation of both syndromes, we conclude that phenotypic changes related to haploinsufficiency of PTCH and ROR2 are recognisable in our patient even at a young age and in the presence of the more complex phenotype due to the deletion's large size. Thus the efforts to identify the genes included in a deletion are worthy as they may result in better care of the patient as, in this case, monitoring the possible development of tumours associated with NBCCS.
KeywordsNBCCS Robinow syndrome Chromosome 9 Chromosome deletion Metacarpophalangeal profile
Nevoid basal cell carcinoma syndrome
brachydactyly type 1B
short tandem repeats