The immature platelet fraction: creating neonatal reference intervals and using these to categorize neonatal thrombocytopenias.

OBJECTIVE: The immature platelet fraction (IPF) is a laboratory measurement analogous to the reticulocyte count, but reflecting the thrombopoietic state. Similar to a reticulocyte count, it can be expressed as a percent (IPF%=percent of platelets that are immature) or as an absolute number per µl blood; the immature platelet count (IPC=IPF% × platelets per µl of blood). STUDY DESIGN: Using a retrospective analysis of de-identified data from non-thrombocytopenic neonates, we created reference intervals for IPF% and IPC. We then tested the value of these measurements for categorizing thrombocytopenic neonates. RESULTS: New charts display reference intervals for IPF% and IPC on the day of birth according to gestational age, and during the first 90 days after birth. Neonates with hyporegenerative varieties of thrombocytopenias (syndromes, small for gestational age, birth asphyxia) had lower IPF% and IPC than did neonates with consumptive thrombocytopenias (immune-mediated, infection, disseminated intravascular coagulation, necrotizing enterocolitis; both P<0.0001). CONCLUSION: The new reference interval charts can be used to recognize abnormal IPFs. The IPF parameters can help clarify the kinetic mechanism responsible for thrombocytopenias in neonates.

The iron status at birth of neonates with risk factors for developing iron deficiency: a pilot study.

OBJECTIVE: Small-for-gestational-age (SGA) neonates, infants of diabetic mothers (IDM) and very-low-birth weight premature neonates (VLBW) are reported to have increased risk for developing iron deficiency and possibly associated neurocognitive delays. STUDY DESIGN: We conducted a pilot study to assess iron status at birth in at-risk neonates by measuring iron parameters in umbilical cord blood from SGA, IDM, VLBW and comparison neonates. RESULTS: Six of the 50 infants studied had biochemical evidence of iron deficiency at birth. Laboratory findings consistent with iron deficiency were found in one SGA, one IDM, three VLBW, and one comparison infant. None of the infants had evidence of iron deficiency anemia. CONCLUSIONS: Evidence of biochemical iron deficiency at birth was found in 17% of screened neonates. Studies are needed to determine whether these infants are at risk for developing iron-limited erythropoiesis, iron deficiency anemia or iron-deficient neurocognitive delay.

Comparing automated vs manual leukocyte differential counts for quantifying the 'left shift' in the blood of neonates.

OBJECTIVE: The neutrophil 'left shift' can be measured via the immature to total (I/T) neutrophil ratio or the absolute bands per µl using a manual differential count. It can also be measured from an automated differential count by the immature granulocyte percentage (IG%) or the absolute IG per µl. In neonates, it is unknown if the manual or automated differential count is superior. STUDY DESIGN: We directly compared complete blood counts (CBCs) with manual and automated differential counts from infants <90 days old, and documented whether or not each neonate was infected. We developed reference intervals for I/T ratio, bands per µl, IG% and IG per µl using values from non-infected neonates. RESULTS: The database had 10 714 CBCs. The upper reference interval for I/T ratio was 0.29 in the first 48 h and 0.31 thereafter; bands per µl was 3710 µl(-1) in the first 48 h and 1785 µl(-1) thereafter. IG% was 6.2% then 4.2%; IG per µl was 1460 µl(-1) then 613 µl(-1). Statistical performances of the four methods were equivalent for identifying infection. CONCLUSIONS: We developed reference intervals for four methods of quantifying a neonate's 'left shift'. The information from automated differentials is not inferior to that from manual differentials in identifying infections, but automated differentials have the advantages of a larger sample size, being less expensive, and faster performance times.

Both initial red cell distribution width (RDW) and change in RDW during heart failure hospitalization are associated with length of hospital stay and 30-day outcomes.

INTRODUCTION: We examined the predictive ability of red cell distribution width (RDW) and the change in RDW during hospitalization (ΔRDW) for length of stay (LOS) and 30-day outcomes after heart failure (HF) inpatient stay. METHODS: Electronic query of Intermountain Healthcare medical records identified patients (N = 6414) with a primary diagnosis of HF who were discharged between 2004 and 2013, had RDW measured within 24 h after admission, and had RDW tested at least once more during the same hospitalization. ΔRDW was defined as the last RDW within 24 h prior to discharge minus the first RDW. RESULTS: Median LOS by initial RDW quartiles was Q1: 3.0, Q2: 3.1, Q3: 3.7, and Q4: 4.0 days (P-trend<0.001), and by ΔRDW quartiles was Q1: 4.1, Q2: 3.4, Q3: 3.6, and Q4: 4.7 days (P-trend<0.001). Both initial RDW (16.8 ± 2.8% vs. 16.3 ± 2.7%, P < 0.001) and ΔRDW (0.21 ± 1.09% vs. 0.14 ± 1.04%, P = 0.039) predicted 30-day readmission vs. no readmit. For 30-day decedents vs. survivors, initial RDW was 17.3 ± 3.0% vs. 16.3 ± 2.6% (P < 0.001), while ΔRDW was +0.20 ± 1.14% vs. +0.14 ± 1.04% (P = 0.15). CONCLUSIONS: Greater initial RDW and ΔRDW during HF hospitalization were associated with 30-day mortality, longer LOS, and 30-day all-cause readmission, suggesting both ΔRDW and initial RDW may aid in personalizing prognosis and treatment.

Reference intervals for reticulocyte parameters of infants during their first 90 days after birth.

OBJECTIVE: The automated reticulocyte parameters (absolute reticulocyte count, immature reticulocyte fraction (IRF) and reticulocyte hemoglobin content (RET-He)) are of value in managing adults and older children with a variety of hematological disorders. However, the lack of reference intervals for these parameters in neonates and young infants has limited their application to that population. STUDY DESIGN: During a span of 12 months (29 May 2014 to 5 May 2015), a convenience sample of reticulocyte parameters were run from clinically ordered complete blood counts (CBCs) of infants within the first 90 days after birth. Measuring the reticulocyte parameters as a research-only adjunct to the CBC did not require any additional blood or generate a patient charge, and the reticulocyte results were not reported to the provided and did not appear in the clinical records. Values from neonates who had a transfusion or a diagnosis of anemia were subsequently excluded from the reference data set. RESULTS: Nine Intermountain Healthcare clinical laboratories contributed 8438 CBCs to the initial reticulocyte parameter database. From these, 1806 were excluded because of a transfusion or a diagnosis of anemia, leaving 6632 in the reference interval database. The parameters charted over the first 90 days after birth were: (1) blood hemoglobin concentration (g dl(-1)), (2) mean corpuscular volume (fL), (3) reticulocyte count (x10(3) per µl), (4) IRF (%) and (5) RET-He (pg). CONCLUSIONS: The new reference interval charts can help clinicians identify abnormalities in the reticulocyte parameters. This information could be of value in identifying and following neonates with various hematological problems including hemolytic disorders, occult hemorrhage, or iron deficiency or other limitations of erythrocyte production.

Whole-blood viscosity in the neonate: effects of gestational age, hematocrit, mean corpuscular volume and umbilical cord milking.

OBJECTIVE: The American College of Obstetrics and Gynecology Committee on Obstetric Practice recently endorsed delayed cord clamping at preterm delivery. However, the committee report expressed the concern by some practitioners that delayed clamping or cord milking might induce hyperviscosity in preterm neonates. To address this issue we: (1) established reference ranges for whole-blood viscosity among preterm neonates (viscosity reference ranges had previously been reported only in term neonates) and (2) determined the effect of umbilical cord milking at deliveries <32 weeks gestation on subsequent blood viscosity measurements. STUDY DESIGN: This was a prospective study in two Neonatal Intensive Care Units. Blood viscosity was measured using a cone and plate viscometer. Associations were sought with gestation, hematocrit/hemoglobin and mean corpuscular volume. Reference ranges were determined for preterm infants <32 weeks gestation. Then, after umbilical cord milking at deliveries <32 weeks, viscosity was measured at birth and again during the 12 h after birth. In neonates with viscosities >95th % range, we sought signs of hyperviscosity (plethora, hypotonia, hypoglycemia, hyperbilirubinemia, thrombocytopenia). RESULT: Viscosity at higher and lower sheer rates were linearly related (n=32, r=0.971). Within the range of hematocrits measured (29-63%) viscosity correlated with hematocrit (r=0.877) and hemoglobin (r=0.853) but not with erythrocyte size (r=0.179). Viscosity was related to gestational age (n=58), primarily due to the lower hematocrits at lower gestational ages. In the 12 h after cord milking viscosity ranged from 3.1 to 9.5 centipoise. Three of twenty preterm, neonates had viscosities >95th % reference range. However, all values were well below those where hyperviscosity is defined in term neonates and all lacked features of hyperviscosity. CONCLUSION: Cord blood viscosity is directly proportional to hematocrit/hemoglobin, lower at early gestation and not associated with erythrocyte size. Cord milking at preterm delivery is associated with a low risk of clinical hyperviscosity. Practioners should not refrain from cord milking at preterm delivery because of a concern that it will commonly cause neonatal hyperviscosity.

Severe neonatal anemia from fetomaternal hemorrhage: report from a multihospital health-care system.

OBJECTIVE: The incidence of fetomaternal hemorrhage that is severe enough to cause neonatal anemia is not known. Owing to its relative rarity, much of the literature describing this condition is in the form of case reports and small case series. We performed a large, muiticentered, sequential, case series to determine the incidence, antecedents and outcomes. STUDY DESIGN: From the multicentered databases of Intermountain Healthcare, we obtained records of all neonates with hematocrit (Hct) <30% or hemoglobin (Hgb) <10 g dl(-1) on the day of birth, who had Kleihauer-Betke staining or flow cytometric evidence of fetomaternal hemorrhage. RESULT: Among 219,853 live births, 24 had anemia with evidence of fetomaternal hemorrhage (incidence estimate, 1 per 9160 live births). The initial Hgb ranged from 1.4 to 10.2 g dl(-1) (Hct 29.8%). The initial Hgb was <7 g dl(-1) in 18 (67%), <5 g dl(-1) in 12 (50%) and was <3 g dl(-1) in 7 (29%). All 7 mothers in whom neonatal Hgb was <3 g dl(-1) had reported absent fetal movement, as did 13 of 18 mothers when the initial Hgb was <7 g dl(-1). Outcomes were poorer in those with the lowest initial Hgb; in the two lowest, one died on day 1, and the other developed a grade 4 intraventricular hemorrhage (IVH). The adverse outcomes of death, IVH, periventricular leukomalacia, bronchopulmonary dysplasia or hypoxic-ischemic encephalopathy were common; occurring in 71% (17 of the 24), including all with an initial Hgb <5 g dl(-1) and all born at ≤35 weeks of gestation. CONCLUSION: Fetomaternal hemorrhage is a rare but sometimes devastating condition. Those with fetomaternal hemorrhage and an initial Hgb of <5 g dl(-1) are expected to need resuscitation at birth, to receive emergent transfusion support and to be at risk for death and major morbidities. Antenatal suspicion of this diagnosis should occur when absent fetal movement is reported. Improvements in rapid diagnosis are needed to prepare first responders and transfusion services.

Cross-calibration of dual-energy X-ray densitometers for a large, multi-center genetic study of osteoporosis.

Osteoporosis is a common disease with a strong genetic component characterized by reduced bone mass and an increased risk of fragility fractures. Bone mineral density (BMD) is the most important determinant of osteoporotic fracture risk, but the genes responsible for BMD regulation and fracture are incompletely defined. To enable multi-center studies to examine the genetic influences on BMD there is a requirement to standardize measurements across different manufacturers of bone densitometers, different versions of machines and different normative ranges. This paper describes a method developed to allow near-identical subjects with low age-adjusted BMD (based on Z-scores) to be recruited in 17 centers using 27 different densitometers. Cross-calibration was based on measurements using a European spine phantom circulated to all centers and measured ten times on each individual machine. From theses values an individual exponential curve, based on nominal versus observed BMD, was derived for each machine. As expected, there were large and significant variations in nominal BMD values, not only between scanners from different manufacturers but also between different versions of scanners from the same manufacturer. Hologic scanners tended to underestimate the nominal BMD, while Lunar scanners overestimated the value. Norland scanners gave mixed values over estimating BMD at the lower nominal value (0.5 g/cm2) while underestimating the value at the higher value (1.5 g/cm2). The validity of the exponential equations was tested using hip and spine measurements on 991 non-proband women from a familial osteoporosis study (FAMOS). After cross-calibration there was a considerable reduction in variation between machines. This observation, coupled with the absence of a similar reduction in variation attributable to a linear regression on age, demonstrated the validity of the cross-calibration approach. Use of the cross-calibration curves along with a standard normative range (in the case of this study, the Hologic normative range) allowed age-specific Z-scores to be used as an inclusion criterion in this genetic study, a method that will be useful for other trials where age-specific BMD inclusion criteria are required.

Genomewide search in familial Paget disease of bone shows evidence of genetic heterogeneity with candidate loci on chromosomes 2q36, 10p13, and 5q35.

Paget disease of bone (PDB) is a common disorder characterized by focal abnormalities of increased and disorganized bone turnover. Genetic factors are important in the pathogenesis of PDB, and previous studies have shown that the PDB-like bone dysplasia familial expansile osteolysis is caused by activating mutations in the TNFRSF11A gene that encodes receptor activator of nuclear factor kappa B (RANK); however, linkage studies, coupled with mutation screening, have excluded involvement of RANK in the vast majority of patients with PDB. To identify other candidate loci for PDB, we conducted a genomewide search in 319 individuals, from 62 kindreds with familial PDB, who were predominantly of British descent. The pattern of inheritance in the study group as a whole was consistent with autosomal dominant transmission of the disease. Parametric multipoint linkage analysis, under a model of heterogeneity, identified three chromosomal regions with LOD scores above the threshold for suggestive linkage. These were on chromosomes 2q36 (LOD score 2.7 at 218.24 cM), 5q35 (LOD score 3.0 at 189.63 cM), and 10p13 (LOD score 2.6 at 41.43 cM). For each of these loci, formal heterogeneity testing with HOMOG supported a model of linkage with heterogeneity, as opposed to no linkage or linkage with homogeneity. Two-point linkage analysis with a series of markers from the 5q35 region in another large kindred with autosomal dominant familial PDB also supported linkage to the candidate region with a maximum LOD score of 3.47 at D5S2034 (187.8 cM). These data indicate the presence of several susceptibility loci for PDB and identify a strong candidate locus for the disease, on chromosome 5q35.

Toward developing a genome-wide microsatellite marker set for linkage analysis in the rhesus macaque (Macaca mulatta): identification of 76 polymorphic markers.

Linkage analysis can be problematic in humans because of the lack of large, multigenerational pedigrees and the difficulties in obtaining phenotypic data on all family members. In contrast, large, captive colonies of rhesus macaque are a potentially valuable resource for linkage studies because detailed phenotypic and genealogical data are kept, inbreeding is avoided, and DNA samples can usually be obtained. Microsatellite marker sets for genome-wide screening are available in a number of species, but not for the rhesus macaque. We tested primers to 400 human microsatellite markers from a genome-wide mapping set using DNA from nine unrelated female rhesus macaques. We found that 76 (19%) of the primers amplified a polymorphic product using the standard protocols for human DNA. The average heterozygosity of the markers in humans was 0.80, compared to 0.65 in the rhesus macaques. This study provides preliminary data, which could be used toward the development of a linkage mapping set in this species. There would be a need, however, to confirm the Mendelian inheritance of the markers.

Evidence that insulin is imprinted in the human yolk sac.

Allelic variation in the size of the insulin (INS) variable number tandem repeat (VNTR) correlates with the expression of both INS in the pancreas and thymus and IGF2 (the gene downstream of INS) in the placenta. In addition, the shorter, class I alleles are associated with type 1 diabetes, whereas the longer, class III alleles are associated with type 2 diabetes, polycystic ovary syndrome (PCOS), and size at birth. Parent-of-origin effects have been reported for type 2 diabetes and PCOS, thus implicating a role for genomic imprinting in these phenotypes. In mice, Ins2 is imprinted and paternally expressed in the yolk sac. In humans, evidence for the imprinting of INS is circumstantial, with occasional monoallelic expression in the thymus. In the present study, we found evidence for the imprinted paternal expression of INS in the human yolk sac. Two other imprinted genes from the same cluster are also expressed monoallelically in the human yolk sac. IGF2 was expressed solely from the paternal allele, and H19 was expressed solely from the maternal allele. These data suggest not only further functional roles for the human yolk sac in early fetal growth, but also evidence for a potential causal link between the control of insulin expression during development and insulin/growth-related diseases in later life.

Evidence for a major gene for bone mineral density in idiopathic osteoporotic families.

Although there have been a number of studies indicating a heritable component for osteoporosis in middle to late adulthood, the etiology of osteoporosis in young people is uncertain. The present study aims to evaluate the extent to which genetic factors influence familial resemblance for bone mineral density (BMD) in families ascertained on the basis of young osteoporotic probands. The sample comprises eight families (74 total individuals) that were identified through a proband under the age of 35 years with a history of two or more fractures and a spinal bone density of at least 2.5 SDs below the mean for age and sex (Z score). Secondary causes of osteoporosis were excluded in the probands. In total, 27% (18/66) of the probands' relatives had osteoporosis and an additional 30% (20/66) had osteopenia. Classical segregation analysis was performed to evaluate the extent to which a genetic etiology could account for familial resemblance in these families. The results indicate a major gene of codominant inheritance for spinal BMD. Model-fitting comparisons revealed no support for environmental effects or for polygenic inheritance.

INS VNTR allelic variation and dynamic insulin secretion in healthy adult non-diabetic Caucasian subjects.

AIMS: To elucidate the relationship between the human insulin gene INS VNTR regulatory polymorphism and insulin secretion. The polymorphism arises from tandem repetition of 14-15 bp oligonucleotides. In Caucasians, repeat number varies from 26 to over 200, with two main and discrete allele size classes: class I (26-63 repeats) and class III (141-209 repeats). Class I allele homozygosity is associated with elevated risk of developing Type 1 diabetes, while the class III allele has been associated with increased risk of Type 2 diabetes, polycystic ovary syndrome (PCOS) and with larger size at birth, which may influence development of adult disease. METHODS: Thirty-one healthy adult subjects with normal glucose tolerance, underwent an intravenous glucose tolerance test with one minute sampling. Seventeen subjects were homozygous for class I alleles (14 excluding individuals carrying alleles associated with parent-of-origin effects and heterogeneity in allele transmission) and 14 homozygous for class III alleles. The groups were well matched. RESULTS: No significant differences in amount or rate of insulin secretion, or beta cell function were detected between the two groups. There was a difference in pattern of pulsatile insulin secretion with more 9-minute oscillations in class I homozygotes (P<0.026). The after-load glucose concentration was also higher in subjects with class I alleles (P<0.03). CONCLUSIONS: These results warrant further analysis of possible association between allelic variation of the INS VNTR and the pulsatility of insulin secretion.

Divergence between genetic determinants of IGF2 transcription levels in leukocytes and of IDDM2-encoded susceptibility to type 1 diabetes.

The IDDM2 susceptibility locus in type 1 diabetes corresponds to a variable number of tandem repeats (VNTR) upstream of the insulin (INS) and insulin-like growth factor 2 (IGF2) genes. Large VNTR alleles (class III) are dominantly protective, whereas small alleles (class I) are predisposing. IGF2 has been considered a prime candidate for mediating IDDM2-encoded susceptibility because of its proximity to the VNTR, mitogenic properties and parental effects at IDDM2 suggest the involvement of an imprinted gene. IGF2 is imprinted with exclusive expression of the paternal gene. However, there is polymorphic relaxation of IGF2 imprinting in leukocytes. VNTR allelic variation affecting either the extent of relaxation or transcription independent of parental origin might explain the IDDM2 effect. To test this, we compared IGF2 expression between chromosomes with a class III or I allele in leukocytes and stimulated lymphocytes. No significant difference was detected between the two classes. Furthermore, the (+) allele of an ApaI polymorphism in the 3'-untranslated region of IGF2 was associated with significantly higher IGF2 messenger ribonucleic acid levels than the (-) allele, but was not associated with type 1 diabetes. The absence of transcriptional effects in leukocytes on IGF2 by the VNTR, which is the disease-predisposing locus, and the presence of a strong association between IGF2 levels and ApaI, which is not associated with the disease, argue against IGF2 expression in leukocytes as the mediator of IDDM2-encoded susceptibility. Taken together, these results support studies suggesting that INS expression in the thymus is a primary target of the IDDM2 susceptibility locus.

Association of the INS VNTR with size at birth. ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood.

Size at birth is an important determinant of perinatal survival and has also been associated with the risk for cardiovascular disease and type 2 diabetes in adult life. Common genetic variation that regulates fetal growth could therefore influence perinatal survival and predispose to the development of adult disease. We have tested the insulin gene (INS) variable number of tandem repeats (VNTR) locus, which in Caucasians has two main allele sizes (class I and class III; ref. 3), as a functional candidate polymorphism for association with size at birth, as it has been shown to influence transcription of INS (refs 3-5). In a cohort of 758 term singletons (Avon Longitudinal Study of Pregnancy and Childhood; ALSPAC) followed longitudinally from birth to 2 years, we detected significant genetic associations with size at birth: class III homozygotes had larger mean head circumference (P=0.004) than class I homozygotes. These associations were amplified in babies who did not show postnatal realignment of growth (45%), and were also evident for length (P=0.015) and weight (P=0.009) at birth. The INS VNTR III/II genotype might have bestowed a perinatal survival during human history by conferring larger size at birth. Common genetic variation of this kind may contribute to reported associations between birth size and adult disease.

Insulin VNTR allele-specific effect in type 1 diabetes depends on identity of untransmitted paternal allele. The IMDIAB Group.

The IDDM2 type 1 diabetes susceptibility locus was mapped to and identified as allelic variation at the insulin gene (INS) VNTR regulatory polymorphism. In Caucasians, INS VNTR alleles divide into two discrete size classes. Class I alleles (26 to 63 repeats) predispose in a recessive way to type 1 diabetes, while class III alleles (140 to more than 200 repeats) are dominantly protective. The protective effect may be explained by higher levels of class III VNTR-associated INS mRNA in thymus such that elevated levels of preproinsulin protein enhance immune tolerance to preproinsulin, a key autoantigen in type 1 diabetes pathogenesis. The mode of action of IDDM2 is complicated, however, by parent-of-origin effects and possible allelic heterogeneity within the two defined allele classes. We have now analysed transmission of specific VNTR alleles in 1,316 families and demonstrate that a particular class I allele does not predispose to disease when paternally inherited, suggestive of polymorphic imprinting. But this paternal effect is observed only when the father's untransmitted allele is a class III. This allelic interaction is reminiscent of epigenetic phenomena observed in plants (for example, paramutation; ref. 17) and in yeast (for example, trans-inactivation; ref. 18). If untransmitted chromosomes can have functional effects on the biological properties of transmitted chromosomes, the implications for human genetics and disease are potentially considerable.

Linkage and association of insulin gene VNTR regulatory polymorphism with polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting up to 10% of women of reproductive age. Women with anovulatory PCOS have hyperinsulinaemia, insulin resistance, and dyslipidaemia, and the syndrome is associated with greatly increased risks of non-insulin-dependent diabetes mellitus and cardiovascular disease and it often clusters in families. The VNTR (variable number of tandem repeats) locus upstream of the insulin gene (INS) regulates insulin expression. We have studied INS VNTR as a candidate genetic locus for susceptibility to PCOS. METHODS: We evaluated linkage of PCOS to the INS VNTR locus on chromosome 11p15.5 in 17 families with several cases, and looked for an association between VNTR and PCOS in two additional clinic populations. VNTR genotypes were designated I/I, I/III, and III/III and linkage disequilibrium mapping was used to test the primary role of the VNTR. FINDINGS: In a group of PCOS/male pattern baldness families, we obtained positive evidence for linkage to 11p15.5 (p = 0.002). The INS VNTR III/III genotype was associated with an increased risk of PCOS in two independent case-control studies (odds ratios 8.20 [p = 0.005] and 5.70 [p = 0.043]). Multilocus linkage disequilibrium mapping suggests that VNTR itself is the predisposing locus. INTERPRETATION: Mapping of susceptibility to PCOS to the INS VNTR implies that PCOS is due, in part, to an inherited alteration in insulin production. The data suggest a mechanistic link between type 2 diabetes and PCOS, which is a risk factor for diabetes later in life.