Microdeletion 15q24 is an emerging syndrome recently described, mainly due to increased use of array-CGH. Clinical features associate mild to moderate developmental delay, typical facial characteristics (high forehead and frontal hairline, broad eyebrows, downslanting palpebral features, long philtrum), hands (particularly proximal implanted thumbs) and genital anomalies (micropenis, hypospadias). We report here on four de novo cases having 2.5-6.1 Mb deletions involving 15q24: one 15q23q24.2 (Patient 1) and three 15q24.1q24.2 deletions (Patients 2-4). We correlate phenotype to genotype according to molecular boundaries of these deletions. Since bilateral iris coloboma and severe ano-rectal malformation were only present in Patient 1, we could link these anomalies to haploinsufficiency of 15q23 genes. Neither hypospadias nor micropenis were present in Patient 3 bearing the smallest deletion, therefore we could define 500 kb 15q24.1 region linked to these anomalies.

We present data on 4 mentally retarded brothers, 2 of whom were dizygotic twins with congenital hypotonia, constipation, head size disproportionately large for length or height, and a combination of minor anomalies suggestive of FG syndrome. These brothers have a mentally retarded full sister with similar minor anomalies and an older half-brother with the Martin-Bell syndrome. The mother is mentally retarded; 4 of 7 individuals are positive for fragile X, but all have a CGG expansion ranging from 0.2-2 to 4 kb. Although the phenotype is not completely typical of the FG syndrome and the coincidence of the FMR1 mutation and segregation of the MCA/MR phenotype are highly unlikely, the FMR1 mutation may affect morphogenesis more extensively and differently than the Martin-Bell syndrome does to effect an FG syndromelike phenotype in certain families. This phenotype does not appear to be a contiguous gene syndrome, but an effect of the FMR1 mutation on an adjacent gene must be considered.