Publications by authors named "Brooke Meader"

3 Publications

  • Page 1 of 1

Increased Burden of Rare Sequence Variants in GnRH-Associated Genes in Women with Hypothalamic Amenorrhea.

J Clin Endocrinol Metab 2020 Sep 1. Epub 2020 Sep 1.

National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC.

Context: Functional hypothalamic amenorrhea (HA) is a common, acquired form of hypogonadotropic hypogonadism that occurs in the setting of energy deficits and/or stress. Variability in individual susceptibility to these stressors, HA heritability, and previous identification of several rare sequence variants (RSVs) in genes associated with the rare disorder, isolated hypogonadotropic hypogonadism (IHH), in individuals with HA suggest a possible genetic contribution to HA susceptibility.

Objective: We sought to determine whether the burden of RSVs in IHH-related genes is greater in women with HA than controls.

Design: We compared patients with HA to control women.

Setting: The study was conducted at secondary referral centers.

Patients And Other Participants: Women with HA (n=106) and control women (ClinSeq study; n=468).

Interventions: We performed exome sequencing in all patients and controls.

Main Outcome Measure(s): The frequency of RSVs in 53 IHH-associated genes was determined using rare variant burden and association tests.

Results: RSVs were overrepresented in women with HA compared with controls (P = 0.007). Seventy-eight heterozygous RSVs in 33 genes were identified in 58 women with HA (36.8% of alleles) compared to 255 RSVs in 41 genes among 200 control women (27.2%).

Conclusions: Women with HA are enriched for RSVs in genes that cause IHH suggesting that variation in genes associated with GnRH neuronal ontogeny and function may be a major determinant of individual susceptibility to developing HA in the face of diet, exercise and/or stress.
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September 2020

Heterozygous Deletions in MKRN3 Cause Central Precocious Puberty Without Prader-Willi Syndrome.

J Clin Endocrinol Metab 2020 08;105(8)

Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland.

Context: Loss-of-function mutations in the imprinted genes MKRN3 and DLK1 cause central precocious puberty (CPP) but whole gene deletions have not been reported. Larger deletions of the chromosome 15q11-13 imprinted locus, including MKRN3, cause Prader-Willi syndrome (PWS). CPP has been reported in PWS but is not common, and the role of MKRN3 in PWS has not been fully elucidated.

Objective: To identify copy number variants in puberty-related, imprinted genes to determine their role in CPP.

Methods: Probands with idiopathic CPP had chromosomal microarray (CMA) and targeted deletion/duplication testing for MKRN3 and DLK1.

Results: Sixteen female probands without MKRN3 or DLK1 variants identified by Sanger sequencing were studied. Whole gene deletions of MKRN3 were identified in 2 subjects (13%): a complete deletion of MKRN3 in Patient A (pubertal onset at 7 years) and a larger deletion involving MAGEL2, MKRN3, and NDN in Patient B (pubertal onset 5.5 years). Both were paternally inherited. Patient B had no typical features of PWS, other than obesity, which was also present in her unaffected family.

Conclusions: We identified 2 cases of whole gene deletions of MKRN3 causing isolated CPP without PWS. This is the first report of complete deletions of MKRN3 in patients with CPP, emphasizing the importance of including copy number variant analysis for MKRN3 mutation testing when a genetic diagnosis is suspected. We speculate that there is a critical region of the PWS locus beyond MKRN3, MAGEL2, and NDN that is responsible for the PWS phenotype.
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August 2020

Insight Into the Ontogeny of GnRH Neurons From Patients Born Without a Nose.

J Clin Endocrinol Metab 2020 05;105(5)

Clinical Research Branch, National Institute of Environmental Health Sciences, Durham, North Carolina.

Context: The reproductive axis is controlled by a network of gonadotropin-releasing hormone (GnRH) neurons born in the primitive nose that migrate to the hypothalamus alongside axons of the olfactory system. The observation that congenital anosmia (inability to smell) is often associated with GnRH deficiency in humans led to the prevailing view that GnRH neurons depend on olfactory structures to reach the brain, but this hypothesis has not been confirmed.

Objective: The objective of this work is to determine the potential for normal reproductive function in the setting of completely absent internal and external olfactory structures.

Methods: We conducted comprehensive phenotyping studies in 11 patients with congenital arhinia. These studies were augmented by review of medical records and study questionnaires in another 40 international patients.

Results: All male patients demonstrated clinical and/or biochemical signs of GnRH deficiency, and the 5 men studied in person had no luteinizing hormone (LH) pulses, suggesting absent GnRH activity. The 6 women studied in person also had apulsatile LH profiles, yet 3 had spontaneous breast development and 2 women (studied from afar) had normal breast development and menstrual cycles, suggesting a fully intact reproductive axis. Administration of pulsatile GnRH to 2 GnRH-deficient patients revealed normal pituitary responsiveness but gonadal failure in the male patient.

Conclusions: Patients with arhinia teach us that the GnRH neuron, a key gatekeeper of the reproductive axis, is associated with but may not depend on olfactory structures for normal migration and function, and more broadly, illustrate the power of extreme human phenotypes in answering fundamental questions about human embryology.
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May 2020