Low anti-Müllerian hormone level is not a risk factor for early pregnancy loss in IVF/ICSI treatment.

STUDY QUESTION: Is a low (<1.0 µg/L) or moderately low (1.0-1.9 µg/L) serum anti-Müllerian hormone (AMH) level a risk factor for early pregnancy loss in IVF/ICSI with a fresh or frozen-thawed embryo transfer (ET)? SUMMARY ANSWER: A low or moderately low serum AMH level does not associate with miscarriage, non-visualized pregnancy loss or overall early pregnancy loss rate in the IVF/ICSI treatment. WHAT IS KNOWN ALREADY: Low AMH predicts poor ovarian response and small oocyte yield in IVF/ICSI treatment, but its value in the evaluation of live birth rate (LBR) is modest. Little is known about the risk of early pregnancy loss in ART among women with low AMH. STUDY DESIGN, SIZE, DURATION: A retrospective cohort study on 1383 women undergoing their first oocyte retrieval for IVF/ICSI in Helsinki University Hospital in Helsinki, Finland, between 2012 and 2016, with all associated fresh (n = 1315) and frozen-thawed (n = 1418) ET cycles finished by August 2018. AMH was measured within 12 months before the IVF/ICSI stimulation. PARTICIPANTS/MATERIALS, SETTING, METHODS: Of all the women, 235 (17.0%) had low (<1.0 µg/L), 278 (20.1%) had moderately low (1.0-1.9 µg/L) and 870 (62.9%) had normal (≥2.0 µg/L) AMH. The primary outcomes were miscarriage, non-visualized pregnancy loss and early pregnancy loss (miscarriage and non-visualized pregnancy loss combined) after fresh or frozen-thawed ET. The impact of AMH on these outcomes was calculated in three populations: among all women who became pregnant, among women with AMH ≤6.0 µg/L and in a population weighted by the inverse probability of becoming pregnant (inverse probability weighting, IPW). The impact of AMH was also assessed on the secondary outcomes, cumulative pregnancy rate (cPR) and cumulative live birth rate (cLBR) across all ET cycles in the woman's first IVF/ICSI. Potential confounders (the woman's age, overweight, smoking, history of endometriosis and underlying medical conditions) adjusted the final results. MAIN RESULTS AND THE ROLE OF CHANCE: Of 1123 pregnancies, 285 (25.4%) ended in non-visualized pregnancy loss and 143 (12.7%) in miscarriage. The LBR was 24.6% per ET (673/2733). Low or moderately low AMH, compared with normal AMH, did not associate with miscarriage or non-visualized pregnancy loss in analyses among all women who became pregnant (adjusted relative risk (RR) for miscarriage vs live birth, 0.70 and 95% CI 0.42-1.17 in low AMH and adjusted RR, 1.00 and 95% CI, 0.68-1.49 in moderately low AMH; adjusted RR for non-visualized pregnancy loss vs live birth, 0.90 and 95% CI, 0.65-1.23 in low AMH and adjusted RR, 1.09 and 95% CI 0.85-1.41 in moderately low AMH), nor did low or moderately low AMH associate with the overall early pregnancy loss rate (adjusted RR for early pregnancy loss vs live birth, 0.86 and 95% CI, 0.68-1.10 in low AMH and adjusted RR, 1.01 and 95% CI, 0.86-1.27 in moderately low AMH). Results remained similar after restricting the analysis to women with AMH ≤6.0 µg/L. Women with low or moderately low AMH had fewer pregnancies and live births than women with normal AMH in their first IVF/ICSI (cPR/cLBR in women with low AMH 50.6/34.0%, moderately low AMH 59.0/36.3% and normal AMH 68.3/49.2%). When the lower probability for pregnancy was considered by using IPW, women with low or moderately low AMH did not have a higher risk for miscarriage, non-visualized pregnancy loss or overall early pregnancy loss compared with women with normal AMH. LIMITATIONS, REASONS FOR CAUTION: The number of miscarriages in women with low AMH was moderately small, limiting the power of the study. The real-world clinical setting of the study restricted the ability to control for all factors causing selection bias. WIDER IMPLICATIONS OF THE FINDINGS: The cLBR was higher among women with normal AMH than among women with low or moderately low AMH in their first IVF/ICSI treatment because these women had more oocytes and embryos. Women with low or moderately low AMH did not have an increased risk for early pregnancy loss. This information is reassuring for couples and useful in counseling. These results are also valuable when assessing the overall effectiveness of IVF/ICSI treatment. STUDY FUNDING/COMPETING INTEREST(S): Research funds from Helsinki University Hospital (no. TYH2018232), Hyvinkää Hospital (no. M3080TUT18) and the Emil Aaltonen Foundation for P.P. Grants from the Paulo Foundation and the Finnish Medical Foundation for H.H. The authors report no conflicts of interest. TRIAL REGISTRATION NUMBER: HUS/138/2017.

Perinatal outcome of children born after frozen and fresh embryo transfer: the Finnish cohort study 1995-2006.

BACKGROUND: The number of children born after frozen embryo transfer (FET) is steadily rising. However, studies on obstetric and perinatal outcomes are limited. Our primary aim was to compare the perinatal health of children born after FET and fresh embryo transfer, and to use data from children born after spontaneous conception as a reference. METHODS: In a register-based cohort study we evaluated the obstetric and perinatal outcomes of children born after FET (n = 2293), fresh embryo transfer (n = 4151) and those born after spontaneous pregnancy (reference group; n = 31 946). Data were collected from the registers of two infertility outpatient clinics, two university hospitals and the Finnish Medical Birth Register (1995-2006). RESULTS: After adjusting for confounding factors the FET group showed decreased risks of preterm birth [adjusted odd ratio (AOR) 0.83, 95% confidence interval (CI) 0.71-0.97], low birthweight (AOR 0.74; 0.62-0.88) and being small for gestational age (AOR 0.63; 0.49-0.83) compared with the fresh embryo transfer group. Mean birthweight was 134 g higher in the FET singletons versus the fresh embryo transfer singletons (P< 0.0001). When FET singletons were compared with the reference group, increased risks of preterm birth (AOR 1.45; 1.25-1.68) and low birthweight (AOR 1.22; 1.03-1.45) and a decreased risk of being small for gestational age (AOR 0.71; 0.54-0.92) were found. No excess of perinatal and infant mortality occurred between the groups. CONCLUSIONS: Embryo freezing does not adversely affect perinatal outcome in terms of prematurity, low birthweight and being small for gestational age versus the fresh embryo transfer and the outcome is similar or even better, particularly regarding fetal growth. Our study, which is one of the largest on FET pregnancies, provides further evidence on the safety of FET.

Obstetric and neonatal outcome after single embryo transfer.

BACKGROUND: Single embryo transfer (SET) pregnancies practically lack vanishing twins and may be associated with improved neonatal outcome. Our objective was to compare the obstetric and neonatal outcome of SET singletons with the outcome of singletons following double embryo transfer (DET) and spontaneous conception. METHODS: A 7-year (1997-2003) cohort of fresh SET (n = 269) and DET (n = 230, including 25 vanishing twins) cycles resulting in singleton birth at Helsinki University Central Hospital, Finland, was linked to the Finnish Medical Birth Register and the obstetric and neonatal outcome data compared with that from 15 037 spontaneously conceived singleton pregnancies. RESULTS: The obstetric and neonatal outcome of the SET group was comparable to that in the DET group. Compared with the comparison cohort, gestational hypertension (P = 0.005), placenta praevia (P < 0.001), preterm contractions (P = 0.01) and maternal hospitalization (P < 0.001) was more typical of women in the SET group. After adjusting for age, parity and socio-economic status the SET pregnancies showed increased risks of Caesarean section [odds ratio (OR) 1.54 with 95% confidence interval (CI) 1.18-2.00], preterm birth (OR 2.85; 95% CI 1.96-4.16) and low birthweight (OR 2.01; 95% CI 1.19-3.99) compared with the comparison cohort. CONCLUSIONS: Our results indicate that subject- and infertility-related mechanisms other than the number of transferred embryos influence the neonatal outcome of singleton IVF pregnancies.

Single embryo transfer is an option in frozen embryo transfer.

BACKGROUND: A good strategy to decrease multiple pregnancy rate in assisted reproduction technology (ART) is the use of single embryo transfer (SET). METHODS: This retrospective study analysed 1647 frozen embryo transfers carried out during 1998-2003 in Helsinki University Central Hospital; of these, 872 were double embryo transfers (DETs) and 775 SETs. The SET group included 140 (18.1%) elective SETs (eSETs). RESULTS: The yearly rate of SETs in frozen cycles increased from 28 to 66%. Overall, the clinical pregnancy rate per frozen embryo transfer was 30.7% and the delivery rate 22.6%. The delivery rate was significantly higher in DET cryocycles than in SET cryocycles (25.7 versus 19.2%, respectively; P < 0.01). In DET cryocycles, the multiple delivery rate was 21.9%, 10 times higher than that observed in cryocycles with SET (2.0%) (P < 0.0001). When eSET was applied, no difference in delivery rate was observed when compared with cryocycles with DET (28.6 and 25.7%, respectively). CONCLUSIONS: SET can be used in frozen cycles to reduce multiple delivery rates.

What is the most relevant standard of success in assisted reproduction?: The value of cryopreservation on cumulative pregnancy rates per single oocyte retrieval should not be forgotten.

The most relevant standard of success in IVF has been discussed widely. An optimal standard should reflect both the risk aspects and the effectiveness of the treatment. The most important parameter for the couple is the ultimate cumulative delivery rate per started cycle. Even if the long-term follow-up of the treatment cycles is difficult in practice, we would stress that more emphasis should be given to embryo freezing, in order to maximize the efficiency of the IVF/ICSI cycles. The contribution of embryo cryopreservation in elective single embryo transfer cycle programmes may result in a cumulative delivery rate of >50%. In Finland, the implementation of single embryo transfer has been possible with good cryopreservation programmes. The effect of this strategy has been seen in a decrease in the proportion of twin deliveries after assisted reproduction, being 13.9% for 2002, as well as a reduction of the proportion of multiple births in the nationwide Medical Birth Registry.

Impact of elective single embryo transfer on the twin pregnancy rate.

BACKGROUND: It is unclear how the implementation of elective single embryo transfer in clinical practice would affect clinical pregnancy and delivery rates and multiple birth rates. METHODS: This retrospective study analysed 1871 IVF/ICSI cycles carried out from 1997 to 2001 in the IVF programme of a single university infertility clinic. RESULTS: The number of elective single embryo transfers increased from 11 to 56%. At the same time the clinical pregnancy rate was relatively stable; mean 34.0% (range 28-42). The number of embryos per embryo transfer decreased from 1.8 to 1.3. The multiple pregnancy and delivery rates dropped markedly from 25 to 7.5% and from 25 to 5% respectively. CONCLUSIONS: An elective single embryo transfer programme can be adopted in daily practice that decreases the twinning rate to <10% and does not affect the overall pregnancy rate.

Regulation of follistatin-related gene (FLRG) expression by protein kinase C and prostaglandin E(2) in cultured granulosa-luteal cells.

Activin and its binding protein follistatin may act as local regulators of cell growth and steroidogenesis in the human ovary. The recently identified follistatin-related gene (FLRG) is expressed abundantly in the human ovary, has high affinity for activin, and is able to inhibit activin-induced transcriptional responses. However, little is known about the regulation of FLRG expression in specific cell types in the ovary, while it is known that gonadotrophins induce follistatin gene expression in human granulosa-luteal cells. In this study, we investigated the expression of FLRG mRNA in granulosa-luteal cells of preovulatory follicles obtained from women undergoing IVF. FLRG mRNA was detected by RT-PCR in fresh and cultured granulosa-luteal cells, as well as in normal ovarian stroma, theca and granulosa cells. Northern blot analysis revealed a 2.5 kb transcript of the FLRG in cultured granulosa-luteal cells. The protein kinase C activator, 12-O-tetradecanoyl phorbol 13-acetate (TPA, 160 nmol/l), and prostaglandin E(2) (PGE(2), 1 micromol/l) increased FLRG mRNA accumulation up to 3-8 fold over the control level after 24 h of treatment, and these stimulatory effects were dose-dependent. Co-treatment with the protein kinase C inhibitor, Ro-31-8220 (3 micromol/l), blocked the stimulatory effect of TPA. Although short term treatment with the protein kinase A activator, (Bu)(2)cAMP (1 mmol/l), slightly reduced FLRG mRNA expression in most experiments, long term treatment with FSH (100 IU/l), LH (100 IU/l), or (Bu)(2)cAMP had no significant effect on the FLRG mRNA levels. As expected, gonadotrophins, protein kinase A and C activators and PGE(2) increased granulosa-luteal cell progesterone secretion into the culture media. Taken together, previous and our present data suggest that protein kinase C and A signal transduction pathways differently regulate the expression of FLRG and follistatin genes in human ovarian granulosa-luteal cells.

Biphasic regulation of activin A secretion by gonadotropins in cultured human ovarian granulosa-luteal cells leads to decreasing activin:inhibin ratios during continuing gonadotropin stimulation.

Pituitary gonadotropins mediate part of their effects on ovarian function via local hormones and growth factors produced by granulosa cells. Activins and inhibins are among these factors, and they have often opposite effects on various components of the reproductive system. The purpose of this study was to investigate the regulation of ovarian activin A secretion using cultured human ovarian granulosa-luteal cells as a model. The granulosa-luteal cells, obtained from women taking part in an in vitro fertilization program, were cultured and treated with FSH, LH, 8-bromo cAMP (8-BrcAMP, a protein kinase A activator) and 12-O-tetradecanoyl phorbol-13-acetate (TPA, a protein kinase C activator). Conditioned cell culture media were analyzed for activin A, inhibin A and progesterone concentrations with specific enzyme immunoassays. FSH and LH (1-100 IU/l) increased activin A secretion with 24 h of treatment (to 132% and 253% of control respectively; P<0.05 for both), but their effects were inhibitory in 48-h treatments (26% and 16% decreases respectively; P<0.05 for both). In the same experiments, FSH and LH increased inhibin A and progesterone secretion after both 24 and 48 h of treatment. 8-BrcAMP (0.1-100 muM) increased activin A in 24- and 48-h experiments (to 206% and 148% of control respectively; P<0.01 for both). Inhibin A and progesterone secretion were stimulated by 8-BrcAMP time- and dose-dependently. TPA increased activin A secretion dose-dependently (0.1-100 ng/ml) in both 24- and 48-h experiments. At 100 ng/ml concentration, it increased activin A up to 61-fold and inhibin A up to 16-fold of control in 24-h experiments. We conclude that gonadotropins regulate immunoreactive activin A secretion biphasically in cultured human granulosa-luteal cells: initial stimulation is followed by inhibition. In contrast, gonadotropins increase inhibin A and progesterone secretion continuously. Consequently, continuing gonadotropin stimulation leads to a decreasing activin:inhibin ratio, which may have a significant role in the local fine-tuning of ovarian steroidogenesis.

The predictive value of pronuclear morphology of zygotes in the assessment of human embryo quality.

BACKGROUND: Recent studies have shown that zygote morphology could be used for the assessment of human embryo quality. Pronuclear (PN) morphology is based on certain distinct features seen in zygotes 16-18 h after fertilization. In the present study PN stage morphology was assessed and combined with a single embryo transfer in order to investigate whether currently used zygote classifications are able to predict embryo quality and implantation rates. METHODS AND RESULTS: Zygotes were analysed according to two different classification systems. In the first, a total of 764 zygotes was analysed according to the degree of polarization of nucleolar precursor bodies (NPB). Zygotes with unpolarized PN (i.e. scattered localization of NPB) showed significantly slower (P < 0.005) cleavage rates (38.9%) than zygotes having at least one pronucleus polarized (57.3% and 54%). However, there was no difference in the pregnancy rate in 105 single embryo transfers between the groups. The appearance of a cytoplasmic halo was related to embryo morphology. Embryos derived from halo-positive zygotes had significantly better (P < 0.05) morphology (60.9%) compared to halo-negative derived embryos (52.2%), but in terms of pregnancy rates no difference was found. A total of 1520 zygotes was analysed according to a second classification system, which was based on the number and distribution of NPB. In the comparative analysis, none of the six different classes produced superior quality embryos or higher pregnancy rates in 144 single embryo transfers. CONCLUSIONS: Our results indicate that there are no significant differences in embryo quality or implantation/pregnancy rates between proposed zygote classes.

One versus two embryo transfer after IVF and ICSI: a randomized study.

BACKGROUND: The main reason for adverse treatment outcome in assisted reproduction is the high rate of multiple pregnancies. The only strategy to avoid dizygotic twins is to transfer one embryo at a time. METHODS: A total of 144 women, who had had at least four good quality embryos available after IVF/intracytoplasmic sperm injection (ICSI) and who had no more than one previous failed treatment cycle, were randomized to have either one or two embryos transferred. The treatment outcomes including those after frozen embryo transfer were compared between these groups. RESULTS: The clinical pregnancy rate per transfer was 32.4% in the one embryo transfer group and 47.1% in the two embryo transfer group, the difference being not significant. Eleven twin deliveries (n = 39) occurred in the two embryo transfer group and there was one pair of monozygotic twins in the one embryo transfer group. The cumulative pregnancy rate per patient after transfer of fresh and frozen embryos was 47.3% in the one embryo transfer group and 58.6% in the two embryo transfer group. CONCLUSIONS: Our results indicate that among women who have good quality embryos in their first IVF/ICSI, good treatment results can be achieved. They support the idea of changing embryo transfer policy towards one embryo transfer without any remarkable decrease in the success rate, while dizygotic twins can be avoided.

Elective single embryo transfer: the value of cryopreservation.

In-vitro fertilization is associated with a high rate of multiple pregnancies, a consequence of the number of embryos transferred. There is a challenge in avoiding even twin pregnancies in assisted reproduction, and this can be accomplished with elective single embryo transfer and a good cryopreservation programme. In our follow-up study, we analysed all our elective single embryo transfers during 1998-1999. In all these cycles at least one embryo was frozen. A total of 127 elective single embryo transfers were performed with a clinical pregnancy rate of 38.6%. The highest implantation rate was obtained with four-cell embryos with <10% fragmentation (39.8%). Thirty-four patients have delivered (26.8%), one of these being a monozygotic pregnancy. In total 129 frozen-thawed cycles have been achieved in 83 patients. One frozen-thawed embryo has been transferred in 46 cycles with a clinical pregnancy rate of 17.4%, and two embryos have been transferred in 83 cycles, with a clinical pregnancy rate of 37.3%. Up until now, 66 of 125 patients in our single embryo transfer programme have delivered or have on-going pregnancies, and 77 still have embryos frozen. The cumulative delivery rate per oocyte retrieval is 52.8% and the twin rate 7.6%. We conclude that elective single embryo transfer with a good cryopreservation programme results in very acceptable pregnancy rates with a low risk of twins. This is a cost-effective practice that substantially reduces all risks associated with multiple pregnancies and lowers the cost per delivery.

Gonadotrophins inhibit and activin induces expression of inhibin/activin beta(B) subunit mRNA in cultured human granulosa-luteal cells.

During the human menstrual cycle, serum inhibin concentrations fluctuate in a cyclic fashion. To examine the regulation of inhibin/activin beta(B) subunit gene expression in ovarian granulosa-luteal cells, the levels of beta(B) subunit mRNA were determined in primary cultures of human granulosa-luteal cells treated with gonadotrophins and protein kinase modulators. Granulosa cells were obtained from women undergoing an IVF programme. The cells were enzymatically dispersed, separated from red blood cells, and maintained in culture for 5--10 days before addition of different agents. Northern blot analysis with specific oligonucleotide probes was performed to study inhibin/activin beta(B) subunit mRNA levels. Both LH and FSH reduced the accumulation of beta(B) subunit mRNA in a dose-dependent manner. The protein kinase A activator, (Bu)(2)cAMP, and the protein kinase inhibitor staurosporine also inhibited beta(B) subunit mRNA expression dose-dependently. Activin A increased dose-dependently beta(B) subunit mRNA expression. Our study suggests that activin-induced and gonadotrophin-inhibited beta(B) subunit expression in granulosa cells might be key factors in the transition from inhibin B to inhibin A dominance during the menstrual cycle.

Regulation of immunoreactive inhibin A and B secretion in cultured human granulosa-luteal cells by gonadotropins, activin A and insulin-like growth factor type-1 receptor.

Inhibins are gonadal glycoproteins with endocrine effects on pituitary FSH secretion and para/autocrine effects on ovarian and testicular function. The purpose of this study was to investigate the endocrine and para/autocrine regulation of inhibin A and inhibin B secretion in human ovarian granulosa-luteal cells. The cells were obtained from women undergoing in vitro fertilization, and the primary cultures were treated with FSH, LH, human chorionic gonadotropin (hCG), activin A, 8-bromo cyclic AMP (8-BrcAMP), staurosporine (a protein kinase C inhibitor) and an antagonist of IGF action (type-1 IGF receptor antibody alpha IR3). The secretion of inhibins was measured by ELISA assays capable of reliably distinguishing between inhibin A and B. FSH, LH, hCG and 8-BrcAMP increased inhibin A secretion on average up to 180% (P<0.01), 192% (P<0.05), 210% (P<0.01) and 243% (P<0.01) respectively of the control level, while their stimulatory effect on inhibin B secretion was less pronounced (up to 167%, P<0.01; 139%, P<0.05; 127%, P>0.05; 133%, P>0.05 of the controls respectively). alpha IR3 decreased inhibin A and B secretion down to 70% (P<0.01) and 50% (P<0.01) respectively of the control. Staurosporine decreased inhibin B secretion down to 49% (P<0.01) of the control; its effect on inhibin A secretion was not significant. Activin A increased inhibin B secretion up to fourfold of the control (P<0.05) while its effect on inhibin A secretion was insignificant. We conclude that gonadotropins via the protein kinase A signal transduction pathway are the main positive regulators of inhibin A and B secretion in human granulosa-luteal cells. The protein kinase C signal transduction pathway seems to be important especially for inhibin B secretion. Locally produced IGFs are probably important inducers of the production of both forms of inhibin in human ovaries while activins seem to upregulate inhibin B secretion.

Seminal plasma glycodelin and fertilization in vitro.

Endometrium-derived glycodelin-A inhibits sperm-egg binding, whereas differentially glycosylated seminal plasma glycodelin-S does not. The difference has been ascribed to the specific type of glycosylation of glycodelin-A. We studied whether the total glycodelin concentration or the relative glycodelin-A concentration in seminal plasma are related to the in vitro fertilization rate of oocytes. We found that total glycodelin levels were significantly higher in a quartile of men with the lowest in vitro fertilization rate compared with the remaining 3 quartiles combined (P = .01). However, for predicting low fertilization capacity of sperm, combining the glycodelin and sperm concentrations by logistic regression analysis did not significantly increase the information obtained from sperm concentration alone. We used specific lectin-immunoassays to determine whether increased glycodelin-A-type glycosylation in seminal plasma would be related to failure to fertilize. No difference was found between the groups with high fertilization and no fertilization in vitro. It is concluded that, although high seminal plasma total glycodelin level has a tendency of being associated with a lower fertilization rate, the difference has limited value to predict fertilization in vitro.

Elective transfer of one embryo results in an acceptable pregnancy rate and eliminates the risk of multiple birth.

To avoid multiple pregnancies without compromising pregnancy rates (PR) is a challenge in assisted reproduction. We have compared pregnancy results among 74 elective one-embryo transfers (group 2) and 94 transfers where only one embryo was available (group 1). All the fresh embryo cycles during 1997 in two clinics in Helsinki were analysed, and cumulative PR among these couples after frozen-thawed embryo transfers up to June 1998 were counted. In group 2, where at least two embryos were available for transfer, and only one was transferred on day 2 or 3, the PR per embryo transfer was 29.7%. In group 1, the PR per embryo transfer was 20.2%. In group 2, the cumulative PR after frozen-thawed embryo transfers was 47.3% per oocyte retrieval. Over the same time, 742 two-embryo transfers were carried out. The PR per embryo transfer was 29.4% in these subjects, but 23.9% of these pregnancies were twins. The implantation rates, as well as the PR, were highest when the embryos were at the four- to five-cell stage on day 2 (35.8 versus 9.7% compared with the two- to three-cell stage, P < 0.001) or at the six- to eight-cell stage on day 3 (45.5%). The PR per embryo transfer was higher when a grade 1 or 2 embryo was transferred compared with a grade three embryo (34. 0 and 26.7% versus 8.8% respectively, P < 0.05). In women 35 years or younger, the PR per elective one-embryo transfer was 32.8%. The corresponding figure in women older than 35 years was 18.8%. On the basis of these results, elective one-embryo transfer can be highly recommended, at least in subjects who are younger than 35 years of age, and who have grade one or grade two embryos available for transfer.

The gene for the familial form of incontinentia pigmenti (IP2) maps to the distal part of Xq28.

Linkage data for familial incontinentia pigmenti (IP2) and 17 X chromosomal markers are reported. The linkage previously found between IP2 and the F8C locus is confirmed (Z max = 11.85 at theta = 0.028). Linkage is established with distal markers DXS1108 (Z max = 10.06 at theta = 0.00) and DXYS154 (Z = 9.07 at theta = 0.019). Multipoint analysis supports the distal localization of the IP2 gene with respect to the F8C locus.

Three Finnish incontinentia pigmenti (IP) families with recombinations with the IP loci at Xq28 and Xp11.

The locus (IP2) for the hereditary form of incontinentia pigmenti (IP) has been mapped to Xq28 by linkage analysis. We studied three IP families with polymorphic markers in the Xq28 region. In two families we observed recombination between the marker loci and IP. In the third family no crossing overs were seen and linkage to the Xq28 region could not be excluded. The other IP locus (IP1) has been mapped to Xp11.21, because of sporadic cases of IP with X-chromosomal alterations involving Xp11.21. To check whether this locus is linked to IP in these families, we used polymorphic markers in the Xp11 region. In all three families recombinations were observed, thus excluding linkage to this locus in these IP families.