遺傳／罕見疾病簡介與遺傳諮詢的運用

Introduction to Genetic/Rare Disease and the Application of Genetic Counseling

遺傳疾病指的是因遺傳物質或遺傳因素改變所造成的疾病，有些會遺傳給下一代或是由上一代遺傳而來，所以具遺傳性是其特點，也就是同樣的疾病會在同一個家族中重複出現。在臺灣，小於萬分之一年盛行率的疾病即定義為罕見疾病。大部份（80%）的罕見疾病是遺傳疾病，但遺傳疾病不一定是罕見疾病。遺傳疾病的致病機轉非常複雜，每一個疾病都有自己獨特的機轉，無法用單一病變機制說明，常常是不明原因，使得遺傳疾病的臨床表現極其多樣化，極端不容易分類和診斷。許多遺傳疾病的患者多會合併發育發展遲緩、器官缺損（如：智障、聽障、視障等）、先天性異常、神經肌肉疾病等。除症狀治療與支持性療法外，只有少數遺傳疾病可以治療（如：部份溶小體儲積症的酵素替代療法，先天性代謝異常的特殊嬰兒配方奶粉）。生活無法自理很常見，家屬身心的負擔也很大。所以完善的復健計畫、早期療育，個別化的照護方案，遺傳諮詢，家庭支持團體的成立皆扮演著重要的角色之外，完善的社會福利制度及大眾的接納更是重要。遺傳／罕見疾病個別的發生率雖低，但整體而言他們是一群不能忽視的疾病。國家政策的制定與立法、疾病登錄系統、全人照護網絡的建置、研究等相關的議題仍舊是一個挑戰。

Genetic disease or hereditary disease is a group of disorders that is caused by mutations in an individual's genome. The mutated genome or gene may be transmitted through the germ line during reproduction, causing certain recurrence risk in offspring and other family members. The heritability of these disorders is thus an important issue to deal with clinically. In Taiwan, a rare disease is defined as a disease that is prevalent in fewer than 1 in 10,000 individuals. As up to 80% of rare disease cases in Taiwan are genetic disease disorders, genetic disease may not rare. The pathophysiology of genetic/ rare disease is very complicated. Individual disorders may have their own unique mechanisms （such as Fragile X syndrome）, with most of these mechanisms still unclear or unknown. The symptoms and signs of genetic/rare disease thus present the greatest variabilities and cause difficulties in making diagnoses. Most related patients may present multiple congenital anomalies, metabolic disorders, growth and developmental delays, defects in cognition, neuromuscular abnormalities, and defects in vision, hearing or other organ functions. Symptomatic and supportive treatment still comprise a major component of treatment of genetic/rare disease （with the exception of special formulae for several inborn errors of metabolic disease and enzyme replacement therapy in some lysosomal storage disease）. Poor self-care ability is common and the burden on caregivers is huge. Most rare disease patients are treated using a comprehensive rehabilitation program that begins during very early childhood, receive individual educational programs, and are continuously monitored with regard to their growth, developmental, and nutritional status. Inter-professional patient care, genetic counseling, and the creation of family support networks play an important role in family management. Public awareness and the creation of appropriate social systems and resources allocation are mandatory for proper care. The incidence of each genetic/rare disease is rare, but collectively they are important public health issue and a challenge to medical care.