Gas chromatographic-mass spectrometric newborn screening for propionic acidaemia by targeting methylcitrate in dried filter-paper urine samples.

Propionic acidaemia (PCCD) or deficiency of propionyl-CoA carboxylase (PCC) is one of the most common organic acidaemias. Recent studies have suggested that this disease can cause somatic or cognitive deterioration even in patients without ketosis or metabolic acidosis, or in cases with unusually late onset. This suggests that for this disease a sensitive yet practical screening procedure is required to achieve early treatment. We conducted a pilot study of gas chromatographic-mass spectrometric screening of 12,000 newborns for PCCD using eluates from dried filter-paper urine collected at 4-7 days of age. Methylcitrate (MC) was targeted for PCCD. For bulk screening, 2-hydroxyundecanoate was used as internal standard; for quantification, stable-isotope-labelled MC was used. Urease pretreatment without fractionation allowed satisfactory recovery and reproducibility of the highly polar MC. We detected an asymptomatic male infant with distinctly elevated MC: the creatinine-corrected level relative to 2-hydroxyundecanoate was 4.8 SD above the normal mean. The MC concentration calculated using the stable-isotope-labelled internal standard was 70.6 mmol/mol creatinine 14.7 SD above the normal mean of 3.70. Parallel analysis of the dried blood spot at 4 days of age by tandem MS showed only borderline elevation of propionylcarnitine. The activity of PCC in lymphocytes was 7% of control. Gene analysis revealed that a single missense mutation, TAT to TGT, resulting in Y435C in the beta chain was present in a homozygous form. Dietary treatment including carnitine supplementation decreased this infant's MC level and to date (at 13 months of age), he shows no neurological or somatic abnormalities.

Fetal arrhythmias: intrauterine diagnosis, treatment and prognosis.

Fetal echocardiography can provide useful information for the evaluation of fetal arrhythmias. Between 1980 and 1993, 44 fetuses with arrhythmias were diagnosed in utero at 12 and 40 weeks of gestation in Kurume University Hospital. Fetal bradycardia, tachycardia and ectopic beats were revealed in 17, seven and 20 fetuses, respectively, and their clinical features and prognosis were evaluated. In the 17 fetuses with bradycardia, eight were associated with congenital heart defect, and six of these developed to fetal hydrops. Of the 17 fetuses, four died in utero, one was terminated, and six died after birth. The other six cases survived. Three of these had a pacemaker implanted after birth. In the seven fetuses with tachycardia, transplacental anti-arrhythmic drugs were administered in five cases and conversion of the arrhythmia was achieved in four. None of the cases was associated with any congenital heart defect, and none died. Three infants had paroxysmal tachycardia postnatally. In the 20 fetuses with ectopic beats, arrhythmia was observed postnatally in 10, but all of these were resolved within 3 months after birth. Fetal bradycardias carried a poor prognosis in most cases and further studies are required to establish effective treatment. Some cases of fetal tachycardia developed recurrent tachycardia postnatally. Close follow-up of the newborn is therefore necessary.