Prenatal Identification and Confirmation of Jacobsen Syndrome: A Series of Four Cases.

Jacobsen syndrome (JBS) is a rare contiguous gene disorder caused by partial deletion of the distal part of the long arm of chromosome 11. Only a few prenatal cases of JBS have been reported, and data on prenatal ultrasonographic findings are relatively scarce. We analysed four cases of JBS diagnosed prenatally in our centre. All four cases received ultrasound examination in the second trimester. Cardiac defects and intrauterine growth retardation (IUGR) were present in three cases. Ventriculomegaly, shortened femur length and pyelectasis were found in two cases. According to the literature, IUGR, pyelectasis and ventriculomegaly are common prenatal phenotypes of JBS. In addition, cardiac defects, trigonocephaly and shortened femur are also found. Our presentation of these cases provides more ultrasonic information for the prenatal diagnosis of this rare disease. Key Words: Ultrasound, Prenatal diagnosis, Jacobsen syndrome, Chromosomal abnormalities, Fetal malformation.

White matter abnormality in Jacobsen syndrome assessed by serial MRI.

INTRODUCTION: Jacobsen syndrome (JS) is caused by a deletion at the terminus of the long arm of chromosome 11. There are few reports of JS associated with cerebral white matter abnormalities (WMA), and the etiology, pathophysiology, and time-dependent changes in WMA with JS still remain unclear. CASE REPORT: The patient was a 2-month-old female with several morphological anomalies, including trigonocephaly, ectropion, flat nasal bridge, low-set ears, and sparse eyebrows. Chromosome analysis (G-banding karyotyping) of 46,XX,del(11)(q23.3) led to the diagnosis of JS. Head MRI performed at age 9 months indicated diffuse WMA with hyperintense signals on T2-weighted imaging. MRI at age 2.5 years demonstrated a decrease in the WMA and progressive myelination. DISCUSSION: These findings suggested that the WMA in the present patient were due to chronic white matter edema associated with a deletion in the 11q terminal region of HEPACAM/GlialCAM, a causative gene for megalencephalic leukoencephalopathy with subcortical cysts type 2B (MLC2B). As with some of MLC2B patients, the WMA in the present patient improved over time. The present report is the first to document dramatic changes in WMA in JS visualized by serial MRI examinations from the neonatal period through early childhood. CONCLUSION: The findings of the present study suggested that WMA in JS are due to chronic white matter edema associated with HEPACAM/GlialCAM deletion and show gradual improvement over time, as seen in some MLC2B patients.

Ultrasonographic findings and prenatal diagnosis of Jacobsen syndrome: A case report and review of the literature.

RATIONALE: Jacobsen syndrome (JBS) is a rare chromosomal disorder with variable phenotypic expressivity, which is usually diagnosed in infancy and childhood based on clinical examination and hematological and cytogenetic findings. Prenatal diagnosis and fetal ultrasonographic findings of JBS are rare. PATIENT CONCERNS: A 38-year-old, gravida 3, para 1, pregnant woman underwent clinical ultrasound examination at 22 weeks of gestation. DIAGNOSES: Ultrasonographic findings indicated an interventricular septal defect, the presence of septal blood flow, dilation of the left renal pelvis, and a single umbilical artery. Amniocentesis was performed to evaluate possible genetic causes of this diagnosis by cytogenetic and single nucleotide polymorphism (SNP) array analysis. INTERVENTIONS: After genetic counseling and informed consent, the couple elected to terminate the pregnancy. OUTCOMES: Karyotype analysis showed that the fetal karyotype was 46,XX,del(11)(q23). The SNP array revealed a 6.118 Mb duplication of 11q23.2q23.3 and a 15.03 Mb deletion of 11q23.3q25. LESSONS: Ultrasonographic findings of fetal JBS, including an interventricular septal defect, dilation of the left renal pelvis, and a single umbilical artery, may be associated with a 15.03 Mb deletion of 11q23.3q25. Further cases correlating phenotype and genotype are required to predict the postnatal phenotype.