Measures of ovarian function in galactosemia — a response to Gubbels et al.

4 06 2009

To the Editor:

We are writing in response to a recent case report by Gubbels and colleagues (1) describing a woman with classic galactosemia who became pregnant shortly after a low anti-mullerian hormone (AMH) blood measurement. The authors contrast their case with results published by our group from a study of 35 galactosemic girls and women (2). We demonstrated that 32/35 of these individuals had low to undetectable AMH, and noted the similarity of this frequency with rates of clinical ovarian insufficiency reported for this patient population. Gubbels and colleagues’ stated objective was “to draw attention to the limited predictive value of ovarian reserve tests” in galactosemics, and they concluded, “Commonly used ovarian function and reserve tests seem to have no significance.” 

While the patient they described is surely of interest, their conclusions are problematic.  A few points:

1.  AMH is made by a subset of maturing follicles.  Low to undetectable AMH does not mean a woman is infertile, but that she has ovarian insufficiency and may be less likely to conceive than other women her same age demonstrating normal levels of AMH.

2.  The young woman is reported as having “undetectable AMH,” although her level is listed as <0.1µg/L.  The lower limit of detection in our study was 0.01µg/L, or ten-fold lower. 

3.  The patient described in the case had galactose 1-phosphate uridyltransferase (GALT) activity measured at 0.82-1.23 µmol/h/g Hb; the reference level was 4.8-30 µmol/h/g Hb.  While the authors state that “the residual activity is too low to have any clinical relevance,” we respectfully disagree.  This level of GALT activity is well above that typically seen in patients with classic galactosemia and may be of great clinical significance.

4.  Gubbels and colleagues suggest that “malfunction of gonadotropins” may underlie the ovarian insufficiency associated with galactosemia.  We tested this hypothesis (Figure 4 [2]); FSH bioactivity in samples from 10 galactosemic patients failed to show a statistically-significant difference compared to the FSH bioactivity in samples from 8 controls.

In summary, we wish to stress that while the conclusions drawn by Gubbels and colleagues may be at odds with our paper, the results of the case are not. Further, both reports agree that, absent surgical removal of the ovaries or uterus, one should never tell a young woman with classic galactosemia that she is absolutely infertile.  We all still have much to learn about the causes, natural history and best predictors of ovarian insufficiency in galactosemia. 

Judith L. Fridovich-Keil, Ph.D.a
Rebecca D. Sanders, B.A.b
Jessica B. Spencer, M.D., M.Sc.c
Michael P. Epstein, Ph.D.a
Joyce W. Lustbader, M.D.d
Pratibhasri A. Vardhana, M.D.d
aDepartment of Human Genetics
bGraduate Program in Biochemistry, Cell and Developmental Biology
cDepartment of Gynecology and Obstetrics
Emory University School of Medicine
Atlanta, Georgia
dDepartment of Obstetrics and Gynecology
Columbia University College of Physicians & Surgeons
New York, New York

References
1.  Gubbels CS, Kuppens SM, Bakker JA, Konings CJ, Wodzig KW, de Sain-van der Velden MG, Menheere PP, Rubio-Gozalbo ME. Pregnancy in classic galactosemia despite undetectable anti-Müllerian hormone. Fertil Steril April 2009 [Epub ahead of print] 

2.  Sanders RD, Spencer JB, Epstein MP, Pollak SV, Vardhana PA, Lustbader JW, Fridovich-Keil JL. Biomarkers of ovarian function in girls and women with classic galactosemia. Fertil Steril. 2008 Aug 4. [Epub ahead of print]

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2009.06.016

The Authors Respond:

We thank Prof. Fridovich-Keil’s group for their comments and take this opportunity to respond to them.

1. “AMH is made by a subset of maturing follicles. Low to undetectable AMH does not mean a woman is infertile, but that she may be less likely to conceive.” We completely agree with this. A low AMH only indicates that there is a lower maturation rate. Whether this is due to fewer primordial follicles, a maturation arrest, or both, remains to be elucidated.

2. The exact level of AMH measured in this patient was 0.018 µg/L. However, since the minimal detectable concentration (MDC, defined as the lowest concentration that can be detected with 95% confidence interval) of this assay was 0.025 µg/L, the concentration in this sample was below the detection limit. The detection limit of 0.01 µg/L, as described by Fridovich-Keil and colleagues in their article (1) was probably also below the calculated MDC in their assays. In fact, we use the same (commercially available) assay and have calculated the MDC of our runs, which varied between 0.018 and 0.039 µg/L. The value of 0.01 µg/L should not have any analytical significance.

3. The level of GALT activity in the described patient is 0.70-1.23 µmol/h/g Hb during pregnancy [in animal models it has been seen that GALT activity is upregulated during pregnancy (2)]. When calculating the percentage of normal activity, we use our non-carrier reference population, leaving our patient with levels of GALT activity of 2.7-4.7% during pregnancy. Measurement of GALT activity in the neonatal period was 0.58 mmol P/mol Hb/min, corresponding to 0.5 µmol/h/g Hb. This was, however, measured after a blood transfusion, and her GALT activity at this point must have been lower. The patient’s mutation, medical history (including neonatal toxic syndrome, cognitive impairment, premature ovarian insufficiency and diminished bone mineral density) and metabolite levels are in line with a severe classic galactosemia phenotype.

4. Prof. Fridovich-Keil’s group elegantly showed that FSH bioactivity in vitro was within reference range or even higher in a subset of patients (1), in line with earlier observations (3). This does not necessarily exclude FSH malfunction. The FSH signal intensity and duration is regulated through the glycan-dependent isoform pattern (4) which might be affected in this disease (5). Possible FSH-receptor glycan abnormality and subsequent malfunction is not ruled out by the described reactions to exogenous FSH (3, 6), as supraphysiological concentrations are administered. Data regarding isoform patterns in these patients or FSH-FSH receptor interaction are limited. Despite FSH bioactivity being normal, these other mechanisms need to be explored.

In conclusion, we stand by our earlier statement that AMH, as well as the other described ovarian reserve tests, may not be the best predictive factors for pregnancy in these women. If there is a maturation arrest in this disease, AMH will be low despite the presence of primordial follicles. As the etiology is not well understood in classic galactosemia, the value of these tests might differ from that in the general population.

Cynthia S Gubbels, M.D.a
Paul P Menheere, Ph.D.b
M. Estela Rubio-Gozalbo, M.D., Ph.D.a,c
aDepartment of Pediatrics
bDepartment of Clinical Chemistry
cLaboratory of Inherited Metabolic Diseases
Maastricht University Medical Center
Maastricht, The Netherlands

References
1. Sanders RD, Spencer JB, Epstein MP, Pollak SV, Vardhana PA, Lustbader JW et al. Biomarkers of ovarian function in girls and women with classic galactosemia. Fertil Steril;Advance Access published Aug 4, 2008.

2. Rogers SR, Bovee BW, Saunders SL, Segal S. Activity of hepatic galactose-metabolizing enzymes in the pregnant rat and fetus. Pediatr Res 1989;25:161-6.

3. Kaufman FR, Kogut MD, Donnell GN, Goebelsmann U, March C, Koch R. Hypergonadotropic hypogonadism in female patients with galactosemia. N Engl J Med 1981;304:994-8.

4. Ulloa-Aguirre A, Midgley AR, Jr., Beitins IZ, Padmanabhan V. Follicle-stimulating isohormones: characterization and physiological relevance. Endocr Rev 1995;16:765-87.

5. Prestoz LL, Couto AS, Shin YS, Petry KG. Altered follicle stimulating hormone isoforms in female galactosaemia patients. Eur J Pediatr 1997;156:116-20.

6. Menezo YJ, Lescaille M, Nicollet B, Servy EJ. Pregnancy and delivery after stimulation with rFSH of a galatosemia patient suffering hypergonadotropic hypogonadism: case report. J Assist Reprod Genet 2004;21:89-90.

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2009.06.017

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2 responses

9 06 2009
Murat Sonmezer, MD

We read with great interest the case report by Gubbels et al. indicating a pregnancy despite undetectable AMH levels in patient with classical galactosemia (1). A similar 22-year-old patient with compound heterozygote mutation for GALT gene (Duarte type) K285N/N314D (2) presented to our clinic with a history of two blighted ova and a spontaneous pregnancy resulted in delivery and subsequent death of a galactosemic infant. The couple suffered from infertility for 3 years at admission to our infertility center. On initial evaluation day 3, FSH was 6.2 IU/ml, E2 was 20 pg/ml and AFC was 8. The husband, who had asthenozospermia, had a heterozygous Q188R mutation of GALT gene. The couple previously underwent insemination cycles for three times and one ICSI cycle prior to admission to our unit. In the first ICSI cycle a suboptimal ovarian response, with 4 M2 and 5 immature oocytes, occurred after controlled ovarian stimulation (COH) with 225 IU rFSH. notably, none of the oocytes fertilized. In the next cycle, a PGD was scheduled due to previous galactosemic infant delivery, recurrent pregnancy loss and total fertilization failure (TFF). In the second ICSI cycle at our clinic, 5 immature and 3 M2 oocytes were retrieved following COH with 225 IU rFSH, and TFF occurred again. With an aim to decrease the toxic effects of the high galactose on the gonads, a galactose free diet was recommended to the couple for 4 months. In the third ICSI cycle, 5 M2 along with 3 immature oocytes were retrieved following COH with 150 IU rFSH and 75 IU hMG. After combined use piezo electrical stimulation and ICSI, 1 grade B and 2 C embryos could be generated. Despite poor quality, all embryos underwent embryo biopsy, but none of them were found normal for GALT gene.

It is still unclear whether infertility, ovarian failure or diminished ovarian reserve and subsequent poor obstetric outcome are associated with non-classical galactosemia. Patients with low erythrocyte GALT activity had a 14-fold increased risk of menopause compared to those with normal GALT activity. Cramer et al. (3) also described significantly higher serum FSH levels in patients heterozygous for the Q188R mutation or the Duarte variant. Conversely, no increased risk for POF, infertility or spontaneous pregnancy loss was noted in women with a galactosemic child (4). Moreover Mlinar et al. purported that a 50% decrease in GALT activity in Q188R or K285N heterozygotes, or the 25% decrease in GALT activity in Duarte heterozygotes, do not compromise ovarian function (5). In our case, a notable spectrum began with poor obstetric outcome, continued with infertility, inadequate ovarian response to stimulation, and manifested as TFF or poor quality embryos despite galactose free diet, all of which might have been related with impaired ovarian function. Even though the genetic composition of the male partner might have contributed to the spectrum of poor reproductive outcome in our case, and despite the fact that no clear connection was demonstrated, it cannot simply be ruled out that there is no association between POF, or diminished ovarian reserve and mutations in GALT gene.

Murat Sonmezer, M.D.(a,b)
Batuhan Özmen, M.D.(a,b)
Volkan Baltacı, M.D.(c)
Cem Somer Atabekoglu, M.D.(a,b)

(a)Department of Obstetrics and Gynecology
Ankara University School of Medicine
(b)Ankara University Center for Research on Human Reproduction
(c)Department of Genetics
Ufuk University School of Medicine
Ankara, Turkey

References
1. Gubbels CS, Kuppens SM, Bakker JA et al. Pregnancy in classic galactosemia despite undetectable anti-Müllerian hormone. Fertil Steril 2009;91:1293.

2. Elsas LJ, Dembure PP, Langley S et al. A common mutation associated with the Duarte galactosemia allele. Am J Hum Genet. 1994:54:1030-6.

3. Cramer DW, Barbieri RL, Xu H, Reichardt JK.Determinants of basal follicle-stimulating hormone levels in premenopausal women.J Clin Endocrinol Metab. 1994:79:1105-9.

4. Sayle AE, Cooper GS, Savitz DA. Menstrual and reproductive history of mothers of galactosemic children. Fertil Steril. 1996;65:534-8.

5. Mlinar B, Gersak K, Karas N, Zitnik IP, Battelino T, Lukac-Bajalo J. Galactose-1-phosphate uridyl transferase gene mutations in women with premature ovarian failure. Fertil Steril 2005;84:253-5.

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2009.06.051

24 06 2009
M. Estela Rubio-Gozalbo, MD, PhD

We thank Dr. Sönmezer et al. for their interesting case report on their Duarte galactosemia patient. We think it touches upon many details that are worthy of note.

The major differences between their patient and the patient we describe, however, are the phenotype and genotype. We report a woman with the classic galactosemia phenotype who is compound heterozygous for two mutations that severely affect GALT activity.

The authors question whether the fertility problems observed in this couple could be due to the GALT- mutation carriership. Existing data on the effect of galactosemia-carriership on female fertility are indeed not conclusive, also studied by Knauff et al. (1). So far, follow-up of patients with Duarte galactosemia has not indicated any clinical effect of the disease. Specifically, in a cohort of Duarte patients, published by Ficicioglu et al. (2), all female (prepubertal) patients had normal FSH levels.

Cynthia S. Gubbels, MD
M. Estela Rubio-Gozalbo, MD, PhD
Maastricht University Medical Center
Maastricht, The Netherlands

References

1. Knauff EA, Richardus R, Eijkemans MJ, Broekmans FJ, de Jong FJ, Fauser BC et al. Heterozygosity for the classical galactosemia mutation does not affect ovarian reserve and menopausal age. Reprod sci 2007;14:780-5.

2. Ficicioglu C, Thomas N, Yager C, Gallagher PR, Hussa C, Mattie A et al. Duarte (DG) galactosemia: a pilot study of biochemical and neurodevelopmental assessment in children detected by newborn screening. Mol Genet Metab 2008;95:206-12.

Published online in Fertility and Sterility doi.org/10.1016/j.fertnstert.2009.06.050

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