Tetralogy of Fallot with absent pulmonary valve in a de novo derivative chromosome 9 with duplication of 9p13 → 9pter and deletion of 9q34.3

Prenatal diagnosis of a de novo 9p terminal chromosomal deletion in a fetus with major congenital anomalies

OBJECTIVE

We describe a prenatal ultrasonography diagnosis of omphalocele and symbrachydactyly in a fetus and review the literature on prenatal diagnosis of 9p terminal chromosomal deletions.

CASE REPORT

A 31-year-old woman (gravida 3, para 1) was referred for genetic counseling because a fetal omphalocele had been detected. Prenatal ultrasonography at 17+ weeks of gestational age revealed a singleton female fetus with biometry equivalent to 18 weeks with an omphalocele. In addition, symbrachydactyly was also noted in the right arm; the wrist bones as well as the metacarpals were missing. A chromosomal study was arranged for a congenital anomaly involving omphalocele. We obtained Giemsa-banded chromosomes from fetal tissue cells, and an abnormal male karyotype with a terminal deletion of the short arm of chromosome 9 at band 9p13 was noted. After delivery, the fetus showed omphalocele, symbrachydactyly, trigonocephaly, sex reversal, a long philtrum, low-set ears, telecanthus, and a frontal prominence.

CONCLUSION

Prenatal diagnosis of abnormal ultrasound findings with omphalocele and symbrachydactyly should include the differential diagnosis of a chromosome 9p deletion.

Absent pulmonary valve, intact interventricular septum, rudimentary aortic non-coronary cusp and ascending aortic aneurysm in a single patient

Absent pulmonary valve (APV) is a relatively rare congenital heart disease, and is mostly associated with tetralogy of Fallot phenotype or ventricular septal defect. APV with intact interventricular septum (IVS) is even less common with case reports or very small series in the literature. Congenital aortic regurgitation with a rudimentary non-coronary cusp is also by itself a rare congenital anomaly and to our knowledge this is the first report of the combination of APV, intact IVS, abnormal aortic valve and ascending aortic aneurysm. The clinical course, possible etiologies and management are discussed.

The chromosome 9q subtelomere deletion syndrome

The chromosome 9q subtelomere deletion syndrome (9qSTDS) is among the first and most common clinically recognizable syndromes to arise from widespread testing by fluorescent in situ hybridization (FISH) of subtelomere deletions. There are about 50 reported cases worldwide. Affected individuals invariably have severe hypotonia with speech and gross motor delay. The facial gestalt is distinct and features absolute or relative micro- or brachycephaly, hypertelorism, synophrys, and/or arched eyebrows, mid-face hypoplasia, a short nose with upturned nares, a protruding tongue with everted lower lip and down-turned corners of the mouth. Approximately half of affected individuals have congenital heart defects (primarily ASD or VSD). A significant minority have epilepsy and/or behavioral and sleep disturbances. A variety of other major and minor eye, ear, genital, and limb anomalies have been reported. Most patients have sub-microscopic deletions of the subtelomere region of chromosome 9q34.3 that range from <400 kb to >3 Mb. The 9qSTDS is caused by haplo-insufficiency of EHMT1, a gene whose protein product (Eu-HMTase1) is a histone H3 Lys 9 (H3-K9) methyltransferase. This was established by identification of three patients with features of the syndrome and either mutations or a balanced translocation in EHMT1. H3-K9 histone methylation is restricted to the euchromatin of mammals and functions to silence individual genes. Deletion size does not correlate with the severity of the 9qSTDS since patients with mutations in EHMT1 are as severely affected as those with submicroscopic deletions. Patients clinically suspected of having the 9qSTDS but with normal subtelomere deletion testing by FISH or MLPA should be considered for detailed 9q MLPA analysis and/or sequencing of EHMT1. EHMT1 is another example in the growing list of genes responsible for brain development that appear to play a role in chromatin remodeling. Published 2007 Wiley-Liss, Inc.