Suormala T, Wick H, Baumgartner E R
University Children's Hospital, Metabolic Unit, Basel, Switzerland.
Eur J Pediatr. 1988 Jun;147(5):478-80. doi: 10.1007/BF00441970.
Screening for biotinidase deficiency has been added recently to some national screening programmes. To clarify the problem of false-positive screening tests in premature infants, we have studied biotinidase activities in the plasma of this population in more detail. In 64 newborns (premature and term babies) biotinidase activities correlated positively with gestational age from the 2nd to the 30th day of life. During the 1st-3rd day the activities were below the normal adult range in all 64 infants. In 56 infants the activities subsequently increased gradually and reached the normal adult range during the 4th-40th day of life. In contrast, the biotinidase activities in eight preterm infants dropped during the 3rd-7th day of life. Impaired liver function as a possible cause for this finding could be ruled out in these infants. The lowest activities in these infants were measured during the 4th-6th day of life, i.e. unfortunately at a time when samples for the screening are normally taken. According to our data, 4-8 out of 48 preterm or small-for-date infants with biotinidase activities ranging from 4.7%-26% of the mean adult value would have given false-positive screening tests. A positive screening test was also obtained in a newborn and in an older unrelated child with a partial biotinidase deficiency. In these children the biotinidase activity did not rise but remained slightly below or at the lower range for heterozygotes (at 31% and 38% of the mean adult value). Currently we do not know whether such individuals are heterozygotes, or whether they have a variant of biotinidase deficiency. However, these children have developed normally without biotin therapy.
最近，生物素酶缺乏症筛查已被纳入一些国家筛查项目。为了阐明早产儿筛查试验假阳性的问题，我们对该人群血浆中的生物素酶活性进行了更详细的研究。在64名新生儿（早产儿和足月儿）中，出生后第2天至第30天，生物素酶活性与胎龄呈正相关。在出生后的第1至3天，所有64名婴儿的生物素酶活性均低于正常成人范围。56名婴儿的生物素酶活性随后逐渐升高，并在出生后第4天至第40天达到正常成人范围。相比之下，8名早产儿的生物素酶活性在出生后第3天至第7天下降。这些婴儿肝功能受损作为这一发现的可能原因已被排除。这些婴儿的生物素酶活性在出生后第4天至第6天最低，即不幸的是，这正是通常采集筛查样本的时间。根据我们的数据，48名早产儿或小于胎龄儿中，生物素酶活性在成人平均值的4.7%至26%之间的4至8名婴儿会出现筛查试验假阳性。一名新生儿和一名无血缘关系的大龄儿童因部分生物素酶缺乏也出现了筛查阳性结果。在这些儿童中，生物素酶活性没有升高，而是略低于杂合子的范围或处于较低水平（分别为成人平均值的31%和38%）。目前我们不知道这些个体是否为杂合子，也不知道他们是否患有生物素酶缺乏症的变异型。然而，这些儿童在未接受生物素治疗的情况下发育正常。
