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遗传的严重肌营养不良症，与脑异常有关。1.在我们最初将FCMD位点定位到染色体9 q31 -33之后，我们发现FCMD和9 q31上的mfd 220之间存在连锁不平衡，然后构建了包含mfd220.2的YAC重叠群。通过连锁不平衡作图，将D9 S2107的候选区域缩小到<100 kb，并构建了含有D9S2107.3的consmid contig。我们研究了FCMD染色体在D9 S2107附近的几个位点的单倍型。结果表明，80%的FCMD携带染色体携带祖先单倍型，95%的FCMD患者携带祖先单倍型同源或异源。除了创始者的单倍型之外，只有少数单倍型。通过founder-haplotype作图，我们预测该基因的位置非常接近E6标记.我们使用D9 S2107周围粘粒重叠群的每个克隆作为探针筛选FCMD中的基因组重排。在大多数具有创始单倍型（86%）的FCMD染色体中，在标记E6附近发现一个约3 kb的插入，该标记E6位于D9 S2107附近约50 kb处。这种插入在正常染色体中的频率与FCMD携带者的频率相匹配。我们对10个FCMD家系和几个FCMD家系进行了产前检查。所有的结果都是正确的。并对30-40个家系进行了遗传学诊断。我们通过对FCMD胎儿的病理学研究表明，胶质界膜的破坏可能是FCMD中小多脑回的主要原因。

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.