Prenatal ultrasound diagnosis of a 48,XXYY syndrome.

The 48,XXYY syndrome is a rare uncommon gonosome aneuploidy and its incidence is estimated to be 1:18,000-1:40,000. The phenotype associated with this syndrome, classically described as Klinefelter variant, is extremely variable but developmental abnormalities are always present. Ultrasound signs during pregnancy are inconsistent, and only three prenatal cases have been described in the literature. Here, we report a case of 48,XXYY syndrome identified in prenatal period because of the presence of polyhydramnios and bilateral clubfeet on second trimester ultrasound. This observation shows the importance of chromosomal prenatal diagnosis in cases with bilateral clubfeet on morphologic ultrasound. This diagnosis is essential for further characterization of the prenatal phenotype and to improving genetic counselling.

De novo unbalanced translocation 2;4 characterized by metaphase CGH and array CGH in a child with mental retardation and dysmorphic features.

BACKGROUND: It is known from postnatal diagnosis that imbalances of the subtelomeric regions contribute significantly to idiopathic mental retardation. PATIENT AND METHODS: We report a case of a 4-year-old child with growth retardation, minor physical abnormalities, hypotonia and developmental delay associated with a derivative chromosome 4. Molecular cytogenetic investigations were performed to characterize the chromosomal rearrangement. RESULTS: Multi fluorescence in situ hybridization revealed the presence of chromosome 2 material on the derivative chromosome 4. Metaphase comparative genomic hybridization detected a terminal 4q34 deletion. Array CGH analysis could precise breakpoints with duplication 2q36 → qter. The clinical phenotype was similar to those described in cases with a trisomy 2qter. CONCLUSION: This study emphasizes the value of array CGH to detect or characterize chromosome rearrangements in mentally retarded patients. Unlike metaphase CGH, the high resolution of array CGH in subtelomeric regions allows an accurate description of chromosomal aberrations.