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Interstitial microdeletions in the long arm of chromosome 3 are rare. In this study, we identified two patients with approximately 5-Mb overlapping deletions in the 3q26.2q26.31 region. Both patients showed neurodevelopmental delays, congenital heart defects, and distinctive facial features. One of them showed growth deficiency and brain abnormalities, as shown on a magnetic resonance imaging scan. Haploinsufficiency of NLGN1 and FNDC3B present in the common deletion region was considered to be responsible for neurodevelopmental delay and the distinctive features, respectively. The possibility of unmasked variants in PLD1 was considered and analyzed, but no possible pathogenic variant was found, and the mechanism of the congenital heart defects observed in the patients is unknown. Because 3q26.2q26.31 deletions are rare, more information is required to establish genotype-phenotype correlations associated with microdeletions in this region., (© 2022 Wiley Periodicals LLC.)

Osteoporosis-pseudoglioma syndrome (OPS; OMIM 259770) is an autosomal-recessive genetic disorder characterized by severe osteoporosis and visual disturbance from childhood. Biallelic mutations in the low-density lipoprotein receptor-related protein 5 gene (LRP5) have been frequently detected, while a subset of patients had only one or no detectable mutation. We report on the clinical and molecular findings of four unrelated Japanese patients with the syndrome. The four patients had typical skeletal and ocular phenotypes of OPS, namely severe juvenile osteoporosis and early-onset visual disturbance, with or without mental retardation. We undertook standard PCR-based sequencing for LRP5 and found four missense mutations (p.L145F, p.T244M, p.P382L, and p.T552M), one nonsense mutation (p.R1534X), and one splice site mutation (c.1584+1G>A) among four OPS patients. Although three patients had two heterozygous mutations, one had only one heterozygous splice site mutation. In this patient, RT-PCR from lymphocytic RNA demonstrated splice error resulting in 63-bp insertion between exons 7 and 8. Furthermore, the patient was found to have only mutated RT-PCR fragment, implying that a seemingly normal allele did not express LRP5 mRNA. We then conducted custom- designed oligonucleotide tiling microarray analyses targeted to a 600-kb genome region harboring LRP5 and discovered a 7.2-kb microdeletion encompassing exons 22 and 23 of LRP5. We found various types of LRP5 mutations, including an exon-level deletion that is undetectable by standard PCR-based mutation screening. Oligonucleotide tiling microarray seems to be a powerful tool in identifying cryptic structural mutations.

We report on a girl with early onset Huntington disease (HD). Her initial symptoms at 2 years of age included oral motor dysfunction and gait disturbance. Magnetic resonance imaging of the head revealed severe atrophy of both the vermis and the cerebellar cortex in addition to the common findings of basal ganglia including the caudate nuclei, putamen, and globus pallidus. Molecular analysis showed 160 CAG repeats in the HD gene. This mutation was inherited from her mother who was also affected, with a HD CAG expansion of 60 repeats. Cerebellar symptoms should be considered as a manifestation of early onset HD.

We describe a 5-year-old boy and a 33-year-old woman with spondyloepimetaphyseal dysplasia with joint laxity leptodactylic form (spondyloepimetaphyseal dysplasia with multiple dislocations) (MIM 6003546), and two 12-year-old girls with the disorder who were previously reported as examples of a variant of sponatrime dysplasia. Their clinical manifestations included midface hypoplasia, micromelic short stature, and generalized joint laxity that caused multiple joint problems, including thoracolumbar scoliosis, hip subluxation, progressive genu valgum with knee and patellar subluxation, elbow subluxation, and malalignment of the wrist. Laryngotracheomalacia was present in two individuals, and myopathy was noted in one. The radiological findings in the four individuals included mild platyspondyly most conspicuous in infancy, narrow interpediculate distances of the lumbar spine evident in infancy, retarded epiphyseal ossification that evolved to epiphyseal dysplasia and later to degenerative joint disease, metaphyseal irregularities and striations present in early childhood, and leptodactylic appearance (slender short tubular bones) of the hand., (Copyright 2002 Wiley-Liss, Inc.)