Known inherited forms of monogenic obesity result

Transcription

1 JCEM ONLINE Advances in Genetics Endocrine Research Homozygous Leptin Receptor Mutation Due to Uniparental Disomy of Chromosome 1: Response to Bariatric Surgery Johanne Le Beyec,* Christine Cugnet-Anceau,* Dominique Pépin, Rohia Alili, Aurelie Cotillard, Jean-Marc Lacorte, Arnaud Basdevant, Martine Laville,** and Karine Clément** From Institut National de la Santé et de la Recherche Médicale (INSERM), Unité (U)872, Team 7, Nutriomique (R.A., A.C., A.B., K.C.) and Team 4 (J.L.B., J.-M.L.), Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers, Paris, France; Assistance Publique-Hôpitaux de Paris, Institut de Cardiométabolisme et Nutrition, Service de Nutrition (R.A., A.B., K.C.) and Service de Biochimie Endocrinienne et Oncologique Unité Fonctionnelle de Nutrigénétique (D.P., J.L.B., J.-M.L.), Pitié- Salpêtrière, Paris, France; and Centre de Recherche en Nutrition Humaine Rhone Alpes, Lyon University (C.C.-A., M.L.), INSERM U1060, CarMeN Laboratory and Centre Européen de Nutrition pour la Santé, University Lyon-1, Hospices Civils de Lyon, Service d Endocrinologie, Diabetologie-Nutrition F Lyon, France Context: Severe early-onset obesity with major hyperphagia associated with hypogonadotropic hypogonadism is recognized as the main clinical presentation of leptin (LEP) or LEP receptor (LEPR) gene complete deficiency. In a few reported cases, homozygous mutations have been found in patients from consanguineous families. Care of LEPR-deficient patients is complicated because they cannot benefit from LEP treatment. Furthermore, gastric surgery may not be recommended in such genetic hypothalamic obesity. Objective: We investigated in a morbidly obese patient the genetic origin of his obesity and evaluated the benefit of bariatric surgery in this case. Subject and Methods: The patient exhibited severe early-onset obesity with hyperphagia and delayed puberty in a nonobese family. He had clinical and hormonal follow-up from 3 to 26 years of age. Gastroplasty procedures were undertaken when he was 16 and 18 years old. LEPR genetic analysis of the patient and his relatives was performed. Results: A new homozygous LEPR sequence frameshift, predicted to generate a truncated protein from a premature stop codon in exon 14, was identified in the proband inherited from two paternal copies of chromosome 1 (isodisomy). Vertical ring gastroplasty was sufficient to induce and maintain a 40-kg weight loss into adulthood. Conclusion: We described the first case of a patient with chromosome 1 uniparental isodisomy revealed by molecular analysis of LEPR. In this case, gastroplasty may be partially effective for weight control as illustrated. (J Clin Endocrinol Metab 98: E397 E402, 2013) Known inherited forms of monogenic obesity result mostly from homozygous mutations affecting genes of the leptin (LEP)-melanocortin pathways (1), a major hypothalamic circuit controlling energy homeostasis. Patients with LEP or LEP receptor (LEPR) mutations are very rare. Most of the patients who had inherited LEP or LEPR complete deficiency were from consanguineous families (2 7). We report here the first case of chromo- ISSN Print X ISSN Online Printed in U.S.A. Copyright 2013 by The Endocrine Society doi: /jc Received July 16, Accepted November 13, First Published Online December 28, 2012 * J.L.B. and C.C.-A. contributed equally to this article. ** M.L. and K.C. also contributed equally to this work. Abbreviations: BMI, Body mass index; HB, Harris-Benedict; LEP, leptin; LEPR, LEP receptor; REE, resting energy expenditure; slepr, soluble LEPR; UPD, uniparental disomy. J Clin Endocrinol Metab, February 2013, 98(2):E397 E402 jcem.endojournals.org E397

2 E398 Le Beyec et al Gastric Surgery in UDP-Induced LEPR Loss J Clin Endocrinol Metab, February 2013, 98(2):E397 E402 some 1 uniparental disomy (UPD), which refers to the inheritance of a chromosome pair from only one parent (8), associated with duplication of a novel LEPR mutation. This genetic abnormality was identified by molecular analysis of the LEPR gene in a patient with morbid obesity and delayed puberty. With the exception of LEP-deficient patients who can benefit from LEP substitution, the management and care of patients with genetic obesity is difficult and frequently unsuccessful. Clinicians and surgeons are reluctant to operate on patients with genetic obesity because of a presumed high postoperative risk. For this patient, bariatric surgery was beneficial in inducing significant and sustainable weight loss over 6 years, suggesting that an intact LEP pathway is not always mandatory for effective bariatric surgery (9). Patient and Methods Case reports The patient was the first offspring of 6 healthy lean siblings born from healthy parents. He was referred to the pediatric hospital at 3.5 years of age for extreme obesity. He was repeatedly evaluated for metabolic and/or endocrine abnormality up to the age of 28. Weight and height were normal at birth but weight became rapidly excessive (Figure 1A). He reached a maximal weight of 180 kg at 17 years of age (Figure 1A). His infancy was marked by uncontrolled appetite, but he had no dysmorphia (Figure 1B). He displayed normal neurodevelopment and completed graduate studies. At 16 years of age, serum LEP concentrations were elevated (162 ng/ml), suggesting a possible deficiency in the LEPR (compared with range [26 86 ng/ml] observed for body mass index [BMI]-matched men), although the LEP concentration did not reach that observed in a previously described patient with another LEPR mutation ( 500 ng/ml) (2). The patient showed clinical and hormonal characteristics of sexual hormone deficiency (scant pubic and no face or axillary hairs) until the age of 19 years. Sexual hormones remained low (Table 1). He was diagnosed with testicular hypotrophy based on clinical and ultrasonographic measurements (right testicle 27/37/20 mm, left testicle 21/38/19 mm). At 20 years of age, bone age evaluated by hand and wrist radiography was 17 years. He had normal human choriogonadotropin hormone stimulation tests (Table 1) at 19 years of age. FSH and LH were normal at 20 years of age. Between 22 and 26 years of age, free testosterone concentration normalized and secondary sexual characteristics appeared (Table 1). He reported satisfactory erections. At 16 years of age, GH secretion in response to stimulation was low (ornithine test, 6.2 ng/ml) but IGF-I levels were appropriate for age. GH replacement was not considered necessary. Linear growth was normal with a final height of 180 cm, close to the midparental height. Free T 4 concentrations were low until 16 years with a normal level of basal TSH up to age 16. Evaluation of the hypothalamohypophyseal-adrenal axis was normal (data not shown). Resting metabolic rate was measured using indirect calorimetry after 12-hour overnight fast at 16, 18, and 19 years old and was compared with values predicted by the Harris-Benedict (HB) equation. Resting energy expenditure (REE) was 16% lower than HB (measured REE 2580 vs 3080 kcal by HB; respiratory quotient, 0.82) at 16 years and 26% lower at 18 years, after the patient benefited from gastroplasty. Resting metabolic rate normalized close to that predicted by the HB equation at 19 years of age (measured REE, 2730 vs 2930 kcal by HB). Methods Written informed consent was obtained from the patient, his parents, and other participants involved in the bariatric surgery program at Pitié-Salpêtrière Hospital (Paris). The other bariatric program participants carried no homozygous mutations in the LEP/melanocortin axis. Written authorization was obtained from the adult patient for the published picture. Genomic sequencing Genomic DNA was extracted from peripheral blood. Screening for mutation in the LEPR gene was performed by direct sequencing (ABI 3730 sequencer; Applied Biosystems, Foster City, California). Sequence data were aligned using the Seqscape version 2.5 software and compared with the LEPR sequence (NM_ ). In silico prediction of the deleterious effect of the mutant was performed with the Alamut Mutation Interpretation Software (Interactive Biosoftware, Rouen, France) and the Poly- Phen Web site ( Results Genetic analysis of the patient and his family Direct sequencing of the patient s LEPR gene revealed homozygous c-1871a duplication (Supplemental Figure 1A, published on The Endocrine Society s Journals Online web site at org) leading to a frame shift in exon 13. This mutation, predicted to generate a premature stop codon in exon 14 (p.asn624lysx21) (Supplemental Figure 1B), could result in the synthesis of a truncated LEPR protein lacking a 521-amino-acid fragment (Supplemental Figure 1B). This truncated LEPR would be shorter than the known LEPR isoforms, including the soluble form of mutated LEPR previously described (2, 10). Mutation analysis in

3 J Clin Endocrinol Metab, February 2013, 98(2):E397 E402 jcem.endojournals.org E399 Figure 1. Clinical evolution of LEPR-mutated patient. A, Weight curve of the proband from birth to adulthood: a, period of energy intake restriction; b, weight before the first gastroplasty by adjustable gastric band; c, removal of gastric ring due to complications; d, weight before the second gastroplasty. B, Picture of the patient at 16 years of age. C, Weight loss evolution of the patient after bariatric surgery. Results are expressed as percent weight variation from basal weight before the intervention. The proband s weight loss (yellow curve) is plotted against morbidly obese patients with gastric banding (n 38 for 3 and 6 months and n 29 for 12 months) (gray curve) followed for 6 or 12 months at Pitié-Salpêtrière Hospital. For comparison, the follow-up of the first patient with LEPR mutation (c G3A) (red curve) is shown and compared with obese patients undergoing gastric bypass (n 281 for 3 and 6 months and n 219 for 12 months) (black curve). This case of a 26-year-old morbidly obese woman affected by a rare homozygous LEPR mutation from a family with several affected siblings was described in 1998 (2). She developed delayed puberty with irregular cycles after the age of 17 years. She had abdominoplasty at age 16 and gastric bypass surgery at 24 years, which led to moderate weight loss. Her highest and lowest adult weights were 220 kg (BMI, 81 kg/m 2 ) and 170 kg (BMI, 62 kg/m 2 ) before and 6 months after the gastric surgery, respectively. She progressively started regaining weight 6 months after surgery. the patient s family revealed homoallelism in the proband (III-2) for the LEPR mutation that was carried by the father (II-3) but surprisingly not by the mother (II-4) (Supplemental Figure 1C). In addition to the father (II-3), two sisters (III-6 and III-7) of the patient were heterozygous carriers of the mutation (Supplemental Figure 1C). Serum concentration of soluble LEPR (slepr) was quantified (Quantikine, human LEP sr immunoassay; R&D Systems Inc, Minneapolis, Minnesota) in the proband, his family, and BMI-matched controls. No slepr was detectable in patient serum (Supplemental Figure 1C, slepr values), suggesting the absence of a secreted mu-

4 E400 Le Beyec et al Gastric Surgery in UDP-Induced LEPR Loss J Clin Endocrinol Metab, February 2013, 98(2):E397 E402 TABLE 1. Serum Hormone Concentrations in the LEPR-Mutated Patient Patient Age, y Leptin, ng/ml BMI expected range LH, IU/L Baseline min iv GnRH Age reference range Testosterone, nmol/l Baseline Age reference range Free testosterone Age reference range GH peak, ng/ml 30 min iv GHRH 9.7 Expected peak min iv ornithine 6.2 Expected peak 17 Somatomedin C (IGF-I), nmol/l Baseline Age reference range TSH, mu/l Baseline Age reference range min iv TRH 32.4 Free T 4, pmol/l Baseline Age reference range The proband was studied several times during infancy at different ages (in years). Normal values appear in italics for each investigated time. IGF-I was measured in basal conditions. tant protein. As expected (10), high serum concentration of slepr was quantified in a previously described LEPRmutated homozygous patient ( 500 ng/ml) (2). slepr levels measured for the patient s relatives without LEPR mutation (Supplemental Figure 1C) were similar to that of BMI- and sex-matched control subjects. Heterozygous carriers of the LEPR mutation have reduced slepr concentrations compared with BMI- and sex-matched control subjects, suggesting the absence of a secreted slepr from the mutated allele (Supplemental Figure 1C). Analysis of microsatellite markers distributed among 11 chromosomes (ampf/str applied kit; Applied Biosystems) (Supplemental Figure 2) showed typical Mendelian inheritance with paternal and maternal alleles found in the patient. Genotype analysis of the father (II-3), the mother (II-4), and the brother (III-4) using microsatellite markers spanning chromosome 1 revealed that the patient (III-2) had inherited a paternal haplotype but no maternal haplotype, indicating the presence of paternal isodisomy of the entire chromosome 1 (Supplemental Figure S1D). Weight loss management in LEPR-mutated patient Extremely controlled restrictive diets and physical activity programs undertaken during infancy were ineffective and always led to weight regain (Figure 1A), as previously shown for patients with LEPR mutations (2, 3, 5). The patient and his parents asked for a bariatric procedure because of worsening obesity. Although gastric surgery might not be recommended in genetic hypothalamic obesity (11), a multidisciplinary consultation meeting was conducted and a collegial decision was reached when the patient was 16 years old. The patient was markedly compliant with diet and physical exercise counseling before and after surgery. A first gastroplasty by adjustable gastric banding led to a significant and impressively well tolerated loss of 46 kg ( 28% of the initial weight of 164 kg) during 1 year but unfortunately had to be removed after 1 year due to gastric band slippage. Rapid weight regain subsequently occurred. A second gastroplasty procedure performed at 18 years of age (weight, 180 kg) led to weight loss of 40 kg ( 20%) and most importantly to weight maintenance after 8 years of follow-up (Figure 1, A and C). However, the weight trajectory was more favorable than for a previously described patient with another LEPR mutation (2) who exhibited limited weight loss and started regaining weight 1 year after gastric bypass procedure (Figure 1C). In this latter case, the patient was unable to follow lifestyle recommendations.

5 J Clin Endocrinol Metab, February 2013, 98(2):E397 E402 jcem.endojournals.org E401 Discussion We describe a first case of morbid syndromic obesity with pubertal delay resulting from paternal isodisomy involving reduction to homoallelism of the LEPR mutated allele. Uniparental isodisomy can result, in case of postzygotic monosomy, from replacement of a missing chromosome by early somatic duplication (12). UPD leads to a specific phenotype if two copies of a recessive mutation are inherited from one parent, as described for our proband with a new LEPR gene mutation (p.asn624lysx21). This mutation is in the region coding for the extracellular portion of the protein and generates a premature translation-termination codon. In silico predicted protein truncation caused by this LEPR mutation makes it likely to be causative of the patient obesity and delayed puberty. Truncated mutant proteins translated from mutant RNAs that escape nonsense-mediated decay are often trafficking-deficient, misfolded, and misrouted; they are consequently subject to endoplasmic-reticulumassociated protein degradation (13). This could explain the lack of slepr in our patient. The patient s obesity phenotype is similar to other rare published cases (2, 3, 5). Most endocrine anomalies (hypogonadism and hypothyroidism) attenuate with time (Table 1) (14 16). Although LEP replacement therapy has proven to be effective in LEP-deficient subjects (17), patients with LEPR mutation cannot benefit from anti-obesity drugs targeting their molecular defect. Usual medical advice based on dietary modification and physical activity shows limited efficacy. Gastric surgery is usually not recommended in patients suffering from genetic and hypothalamic causes of obesity because of severe hyperphagia (11). For example, gastric surgery in obese patients suffering from Prader-Willi syndrome, in which obesity and hyperphagia are associated with impaired cognition, resulted in limited benefits and risks of complications (18). A recent report describes an impaired response to gastric banding with weight regain in a patient with complete melanocortin receptor 4 deficiency (19). The authors suggest a compromised satiety response, without excluding other factors such as noncompliance to recommendation. The relative failure of surgical therapy is also illustrated in our report of rapid weight regain 1 year after bypass performed in 2008 in our first patient with LEPR mutation (Figure 1D). This patient of low socioeconomic status had extreme difficulties after postsurgical counseling. She was noncompliant with the recommendations, and her medical follow-up was very irregular. In contrast, the patient presented here with UPD benefited from gastroplasty, leading not only to significant ( 40 kg from maximum weight) weight loss but also to sustainable weight maintenance after 8 years of regular follow-up. Importantly, he and his family are highly educated and compliant to the recommendations provided in this type of purely restrictive surgery. In summary, we report the first case of UPD detected in a severely obese patient who inherited two paternal chromosomes, one carrying a mutation in the LEPR gene. The clinical phenotype of this patient was similar to that of other obese patients carrying LEPR mutations, but in the present case, bariatric surgery was beneficial, suggesting that an intact LEP pathway is not fully mandatory for effective bariatric surgery (9). Acknowledgments We thank Dr M. Le Gall for the helpful discussions, Dr C. Depienne for kindly providing the microsatellite markers for chromosome 1 genotype analysis (INSERM U975), and Sandrine Moutel for her contribution to iconography. Address all correspondence and requests for reprints to: J. Le Beyec-Le Bihan or K. Clément, Groupe Hospitalier Pitié-Salpêtrière, Boulevard d l Hôpital, Paris Cedex 13, France. johanne.lebihan@psl.aphp.fr or karine.clement@psl.aphp.fr. This work was supported by grants from Assistance Publique- Hôpitaux de Paris and INSERM. This work was supported by the French National Agency through the national program Investissements d Avenir with the reference ANR-10-IAHU-05. Disclosure Summary: There are no potential conflicts of interest related to this report. References 1. Mutch DM, Clement K. Unraveling the genetics of human obesity. PLoS Genet. 2006;2:e Clement K, Vaisse C, Lahlou N, et al. A mutation in the human leptin receptor gene causes obesity and pituitary dysfunction. Nature. 1998;392: Farooqi IS, Wangensteen T, Collins S, et al. Clinical and molecular genetic spectrum of congenital deficiency of the leptin receptor. N Engl J Med. 2007;356: Mazen I, El-Gammal M, Abdel-Hamid M, Amr K. A novel homozygous missense mutation of the leptin gene (N103K) in an obese Egyptian patient. Mol Genet Metab. 2009;97: Mazen I, El-Gammal M, Abdel-Hamid M, Farooqi IS, Amr K. Homozygosity for a novel missense mutation in the leptin receptor gene (P316T) in two Egyptian cousins with severe early onset obesity. Mol Genet Metab. 2011;102: Montague CT, Farooqi IS, Whitehead JP, et al. Congenital leptin deficiency is associated with severe early-onset obesity in humans. Nature. 1997;387: Strobel A, Issad T, Camoin L, Ozata M, Strosberg AD. A leptin missense mutation associated with hypogonadism and morbid obesity. Nat Genet. 1998;18: Engel E. A new genetic concept: uniparental disomy and its potential effect, isodisomy. Am J Med Genet. 1980;6: Sumithran P, Prendergast LA, Delbridge E, et al. Long-term persis-

6 E402 Le Beyec et al Gastric Surgery in UDP-Induced LEPR Loss J Clin Endocrinol Metab, February 2013, 98(2):E397 E402 tence of hormonal adaptations to weight loss. N Engl J Med. 2011; 365: Lahlou N, Issad T, Lebouc Y, et al. Mutations in the human leptin and leptin receptor genes as models of serum leptin receptor regulation. Diabetes. 2002;51: Potoczna N, Branson R, Kral JG, et al. Gene variants and binge eating as predictors of comorbidity and outcome of treatment in severe obesity. J Gastrointest Surg. 2004;8: ; discussion Robinson WP. Mechanisms leading to uniparental disomy and their clinical consequences. Bioessays. 2000;22: Kang JQ, Macdonald RL. Making sense of nonsense GABA(A) receptor mutations associated with genetic epilepsies. Trends Mol Med. 2009;15: Ozata M, Ozdemir IC, Licinio J. Human leptin deficiency caused by a missense mutation: multiple endocrine defects, decreased sympathetic tone, and immune system dysfunction indicate new targets for leptin action, greater central than peripheral resistance to the effects of leptin, and spontaneous correction of leptin-mediated defects. J Clin Endocrinol Metab. 1999;84: Bluher S, Mantzoros CS. Leptin in reproduction. Curr Opin Endocrinol Diabetes Obes. 2007;14: Nizard J, Dommergue M, Clement K. Pregnancy in a woman with a leptin-receptor mutation. N Engl J Med. 2012;366: Farooqi IS, Jebb SA, Langmack G, et al. Effects of recombinant leptin therapy in a child with congenital leptin deficiency. N Engl J Med. 1999;341: Scheimann AO, Butler MG, Gourash L, Cuffari C, Klish W. Critical analysis of bariatric procedures in Prader-Willi syndrome. J Pediatr Gastroenterol Nutr. 2008;46: Aslan IR, Ranadive SA, Ersoy BA, Rogers SJ, Lustig RH, Vaisse C. Bariatric surgery in a patient with complete MC4R deficiency. Int J Obes (Lond). 2011;35: Members receive free electronic delivery of FDA drug safety alerts from the PDR Network.