Isolation of a gene for Fukuyama-type congenital muscular dystrophy and genetic diagnosis

福山型先天性肌营养不良症（FCMD）是日本第二常见的肌营养不良症，是一种常染色体隐性严重肌营养不良症，与大脑异常有关。在我们将fmd基因座定位到染色体9q31-33之后，我们发现fmd与9q31上的mfd220之间的连锁不平衡，然后构建了包含mfd220.2的YAC序列。通过链接-不平衡映射，我们将候选区域缩小到包含D9S2107的<100 kb，构造了包含D9S2107.3的consmid序列。我们在D9S2107附近的几个位点检测了手足口病染色体的单倍型。结果表明，80%携带口蹄疫的染色体携带祖先单倍型，95%的口蹄疫患者携带祖先单倍型为纯合或杂合。除了创始的单倍型，只有几个单倍型。我们通过创始人-单倍型定位预测基因位置与标记E6极近。我们使用位于D9S2107周围的每个cosmid克隆作为探针筛选口蹄疫的基因组重排。在大多数具有创始单倍型的手足口病染色体（86%）中，在标记E6附近发现了一个-3 kb的插入，该标记位于D9S2107附近-50 kb。正常染色体的插入频率与口蹄疫携带者的插入频率相匹配。我们对10个和几个口蹄疫家族进行了产前诊断。所有结果都是正确的。同时，我们对30-40个家庭进行了基因诊断。我们通过对手足口病胎儿的病理研究证明，神经胶质界限的破坏可能是手足口病小多回症的主要原因。

Fukuyama-type congenital muscular dystrophy (FCMD), the second most common form of muscular dystrophy in Japan, is an autosomal recessive severe muscular dystrophy, associated with brain anomalies.1. Following our initial mapping of the FCMD locus to chromosome 9q31-33, we found linkage disequilibrium between FCMD and mfd220 on 9q31 and then constructed the YAC contig encompassing mfd220.2. By using linkage-disequilibrium mapping, we narrowd the candidate region to <100 kb containing D9S2107 and constructed the consmid contig harboring D9S2107.3. We examined haplotypes of FCMD chromosomes at a few loci around D9S2107. The results indicated that 80% of FCMD-bearing chromosomes carried an ancestral haplotype and that 95% of FCMD patients carried ancestral haplotypes homozygously or heterozygously. There were only a few haplotypes other than the founder one. We predicted the gene location extremely proximal to marker E6 by founder-haplotype mapping.4. We screened genomic rearrangements in FCMD using each clone of the cosmid contig around D9S2107 as a probe. A -3 kb insertion was found near the marker E6, which lies -50 kb proximal to D9S2107, in most FCMD chromosomes with the founder haplotype (86%). The frequency of this insertion in normal chromosomes matched well that of FCMD carrier.5. We performed prenatal dianoses of 10 and several FCMD familes. All the results were correct. Also, we conducted genetic diagnosis of 30-40 families. We demonstrated that breaches in the glia limitans may be the primary cause of the micropolygyria in FCMD by pathological study of an FCMD fetus.