Twenty-nine chromosomally normal patients with CDH were studied using the Spectral 1 Mb GenomeChip™ V1.2 arrays. Eleven cases were clinically classified as having isolated CDH, while 18 were classified as having complex CDH. Among those with complex CDH, aCGH demonstrated an abnormality in a single case, a de novo deletion involving chromosome regions 1q41–q42.12. This case was the Twin B product of a dichorionic diamniotic gestation born at 37 1/7 weeks by cesarian for transverse breech presentation to a 31-year-old gravida 3, para 2 woman. Amniocentesis revealed a normal 46,XX karyotype in each twin. Apgar scores for Twin B were 1/1, and the immediate neonatal course was complicated by a difficult endotracheal intubation and an emergency laparotomy for evacuation of a hemoperitoneum. Despite intensive efforts, Twin B died at 1 hr of age. Twin A had a normal physical and developmental examination in the newborn period and again at 3 months of age. Of note during the newborn examination, Twin A's fingernails and toenails were normal in size and larger than those found in Twin B (described below). Twin zygosity could not be established based on placental membranes.
On postmortem examination (), Twin B's weight was 1.81 kg (<10th centile), crown-heel length, 45 cm (normal for gestational age: 44.5 ± 7.0 cm), and head circumference, 30.7 cm (<5th centile). The skull and face were remarkable for slightly coarse features, hypertelorism (inner canthal distance equaling 2.3 cm), a boxy forehead, and large fontanelles (anterior and posterior fontanelles measuring 6 × 4 cm and 3.5 × 8 cm, respectively). Additional distinctive craniofacial findings included a depressed nasal bridge and broad nasal tip, anteverted nares, a short philtrum, a tented upper lip, a midline cleft of the soft palate, and normally formed but slightly low set ears. The extremities showed mild upper arm shortening, positional finger flexion, talipes equinovarus, and moderate hypoplasia of fingernails and toenails. Internal examination revealed a large left Bochdalek diaphragm hernia, mild right diaphragmatic eventration, and bilateral pulmonary hypoplasia (with left and right lungs weighing 1.2 gm and 9.0 gm, respectively; normal combined lung weights for gestational age = 35.0 ± 10.8 gm). The heart was anatomically unremarkable except for a small probe patent muscular ventricular septal defect. The mucosa of the false and true vocal cords was abraded bilaterally, presumably secondary to the traumatic intubation. However, there was abnormal fullness of the supraglottic larynx compared to an age-matched autopsy control, suggesting partial supraglottic and glottic luminal stenosis. Gross and microscopic examination of the kidneys and uterus were both normal.
Fig. 1 Photographs taken during post-mortem examination of Twin B. a: Full body view shows dysmorphic features, mild proximal rhizomelic shortening, right club foot. Bandage across abdomen is secondary to emergency evacuation of hemoperitoneum; b: Close-up of (more ...)
Postnatal karyotype (450 band level, Genzyme Genetics) on a skin biopsy taken at the time of autopsy confirmed the normal amniocentesis results.
aCGH performed on DNA extracted from the proband's fibroblasts demonstrated the loss of three consecutive BAC clones, RP11–124J24 (1q41), RP11–239E10 (1q41–1q42.11), and RP5–1090A23 (1q42.12). Non-deleted flanking probes RP11–553F10 and RP11–27504, which map to 1q41 and 1q42.13, respectively, suggested that the deletion is on the order of 5 million base pairs (). aCGH identified no abnormalities in either parent (). The deletion was confirmed independently in a CLIA-certified laboratory, Signature Genomics, Spokane, WA, using the SignatureChip™ array and FISH (data not shown).
Fig. 2 Spectral Chip 2600™ aCGH results. a: Results from Spectral Chip 2600™ aCGH in proband with the clinical diagnosis of Fryns syndrome. Deletion of three consecutive BAC clones RP11–124J24 (1q41), RP11–239E10 (1q41 – (more ...)
FISH analysis of interphase preparations from Twin B was abnormal with deletion of the following probes: RP11–124J24 (1q41), RP11–239E10 (1q41–1q42.11), and RP5–1090A23 (1q42.12). Deletion of RP11–124J24 (green) is demonstrated in the proband, while both copies of the DXZ1 control probe (red) mapping to the centromere of chromosome 1 are evident (). We confirmed diploid copies of flanking probes in all three subjects; additionally, each parent was diploid for both the chromosome 1q41–1q42.12 and the chromosome 1 centromere probes (data not shown).
FISH results confirming del (1)(q41q42.12): Only a single copy of RP11–124J24 (green) mapping to 1q41 is demonstrated in the proband. Both copies of the control probe DXZ1 (red) mapping to the chromosome 1 centromere region are visible.
Among the 11 patients with isolated CDH, none had an abnormality demonstrated by aCGH. All of the patients in this series had at least one of the previously reported aCGH-CNVs. Additionally, one patient had an approximate 3-Mb duplication of two consecutive BAC clones, AC108710.3 and RP11–91M15, at chromosome 3q11.2 (data not shown). The phenotypically normal mother of this patient demonstrated duplication of the same BACs on aCGH, suggesting this is an inherited CNV.