No abstract

Three-lead electrocardiography and expired CO2 monitoring were used during positive pressure ventilation of seven non-intubated newborns (gestational age, 31-37 weeks; birthweight, 1503-2885 g). In all cases, adequate CO2 (>15 mmHg) was detected prior to the achievement of stable heart rate (>100 beats/min). The delay between detection of adequate CO2 and improvement of bradycardia ranged from 8 to 73 s (median, 15 s). Inadequate expired CO2 during positive pressure ventilation indicates airway obstruction or poor aeration of the newborn lungs. Thus, positive expiratory CO2 can be the first recognizable sign of successful ventilation during neonatal resuscitation.

Cytochrome c oxidase (COX) deficiency is the most common cause of Leigh syndrome (LS). COX consists of ten nuclear-encoded and three mtDNA-encoded structural subunits. Although the nucleotide sequences of all 13 genes are known, no mutation was found in nuclear-encoded subunit genes of COX-deficiency patients. Zhu et al. (1998) and Tiranti et al. (1998) found nine mutations in the surfeit 1 (SURF1) gene in LS families with COX deficiency. The mouse surfeit gene cluster consists of six closely spaced housekeeping genes unrelated by sequence homology. Except for the Surf3 gene, the function is still not known. The juxtaposition of at least five of the surfeit genes is conserved between birds and mammals. We identified two novel mutations of SURF1 in a Japanese LS patient with COX deficiency using direct sequencing analysis. Firstly, a 2-bp deletion at nucleotide position 790 (790delAG) in exon 8 was found, which shifts the reading frame such that the mutant protein has a completely different amino acid sequence from codon 264 to the premature stop codon at 290. Secondly, we found a T-to-G transversion at nucleotide 820, resulting in the substitution of tyrosine by aspartic acid at codon 274 (Y274D). We also studied the parents' genes, and found that the Y274D mutation was in his father and the 790delAG mutation was in his mother heterozygously. Therefore, we concluded that the patient was a compound heterozygote with these mutations. These are the first pathogenetic SURF1 mutations identified in a Japanese family.

The human SOX9 gene is responsible for the campomelic syndrome (CMPS) and sex reversal. This gene encodes a transcription factor containing a DNA binding domain homologous to the SRY high mobility group (HMG) domain. A novel mutation of SOX9, i.e. a single G deletion in one allele at nt 296 from A of the first ATG in the open reading frame, was identified in a patient with CMPS with sex reversal. The deletion resulted in a frameshift mutation upstream of the HMG box and a stop codon 30 bp downstream of the HMG box. The predicted truncated SOX9 protein contained 108 amino acids instead of the 509 amino acids of the normal SOX9 protein, removing nearly 80% of the SOX9 protein, including the HMG and the C-terminal transactivation domain. Most patients with CMPS reported previously died within the neonatal period. Our findings that the patient has survived, although has been in daily need of mechanical ventilation support for 5 years and 3 months despite a severely impaired SOX9 protein, do not support a linear relationship between the type of mutation and severity of the clinical outcome.

No abstract