Clinical and Molecular Studies of the Erythropoietic Protoporphyria Phenotype

应聘者：Manisha Balwani医学博士，医学博士，西奈山医学院遗传学和基因组科学系助理教授，拥有内科和临床遗传学委员会证书。这项资助计划旨在为候选人提供一种有指导的培训经验，以促进她作为一名独立的临床研究人员的发展，专注于卟啉症，即血红素生物合成的先天错误。导师在这些疾病的临床、生化和分子研究方面经验丰富。这些导师在指导研究员和初级教员进行翻译研究、临床试验和药物开发方面有着良好的记录。因此，提供给申请人的指导计划、实验室和临床研究环境将有助于她作为一名独立研究人员的发展。拟议的研究将集中在红细胞生成性原卟啉症(EPP)表型上，这是一组遗传上异质性的光致严重皮肤卟啉症。到目前为止，EPP表型有三种亚型：1)常染色体隐性遗传性EPP，由铁络合酶(FECH)基因“功能缺失”突变所致；2)X-连锁原红细胞增殖症(XLP)，一种新发现的亚型，由X-连锁红系特异性D-氨基乙酰丙酸合成酶(ALAS2)基因“功能获得”突变所致；3)红细胞原卟啉升高、皮肤光敏、FECH和ALAS2等位基因正常的亚型。拟议的研究将首先确定、表征和确定导致EPP表型的FECH和ALAS2突变的频率，这些突变导致100多名已经登记在Porporria Consortium中的无关患者。突变确认的EPP和XLP患者的自然病史、临床谱系、生活质量和红细胞原卟啉水平将被确定。在XLP中，临床表现的存在和严重程度，以及红细胞游离原卟啉和锌原卟啉的水平将被确定在女性杂合子中，并与由于随机X染色体失活的偏斜而在单个杂合子的造血细胞中表达的突变ALAS2等位基因的比例相关。FDA批准的一项新的先导性研究将在EPP和XLP患者中进行，以确定与ALAS2的辅因子磷酸吡哆醛结合的异烟肼是否可以降低ALAS2的活性，从而减少导致XLP表现的红细胞原卟啉的形成。这项裁决提供的保护时间将使申请者成为诊断和管理卟啉症的专家，促进申请者实现建立专注于卟啉病发病机制研究和新疗法开发的独立研究生涯的目标。

DESCRIPTION (provided by applicant): The candidate, Manisha Balwani MD, MS, is an Assistant Professor in the Department of Genetics and Genomic Sciences at the Mount Sinai School of Medicine and is board certified in Internal Medicine and Clinical Genetics. This grant proposal is designed to provide the candidate with a mentored training experience that will facilitate her development as an independent clinical researcher focused on the Porphyrias, the inborn errors of heme biosynthesis. The Mentors are experienced in the clinical, biochemical, and molecular studies of these diseases. The Mentors have a strong record in mentoring fellows and junior faculty in translational research, clinical trials and drug development. Thus, the mentoring program and laboratory and clinical research environment that will be available to the applicant will facilitate her development as an independent researcher. The proposed research will focus on the Erythropoietic Protoporphyria (EPP)-phenotype, a group of genetically heterogenous photo-induced, severe, cutaneous porphyrias. Three subtypes of the EPP-phenotype have been identified to date: 1) autosomal recessive EPP due to "loss- of-function" mutations in the ferrochelatase (FECH) gene, 2) X-linked Protoporphyria (XLP), a newly recognized subtype resulting from "gain-of-function" mutations of the X-linked erythroid-specific d- aminolevulinate synthase (ALAS2) gene, and 3) a subtype with elevated erythrocyte protoporphyrins, cutaneous photosensitivity, and normal FECH and ALAS2 alleles. The proposed studies will initially identify, characterize, and determine the frequency of the FECH and ALAS2 mutations causing the EPP-phenotype in over 100 unrelated patients already enrolled in the Porphyria Consortium. The natural history, clinical spectrum, quality of life, and erythrocyte protoporphyrin levels will be determined in patients with mutation- confirmed EPP and XLP. In XLP, the absence or presence and severity of clinical manifestations, and the levels of erythrocyte free- and zinc-protoporphyrins will be determined in female heterozygotes and correlated with the proportion of mutant ALAS2 alleles expressed in hematopoietic cells from individual heterozygotes due to skewing of random X-chromosomal inactivation. A novel FDA-approved pilot study will be conducted in patients with EPP and XLP to determine if Isoniazid, which binds to pyridoxal phosphate, a co-factor of ALAS2, can decrease the activity of ALAS2, thereby reducing the formation of erythrocyte protoporphyrin, which causes the XLP manifestations. The protected time afforded by this award would permit the applicant to become expert in the diagnosis and management of the porphyrias, facilitate the applicant's goal of establishing an independent research career focused on studies of porphyria pathogenesis and the development of novel treatments.