Definition of minimal duplicated region encompassing the XIAP and STAG2 genes in the Xq25 microduplication syndrome.

Typical Xq25 duplications are large and associated with heterogeneous phenotypes. Recently, small duplications involving this genomic region and encompassing the GRIA3 and STAG2 genes have been reported. These Xq25 microduplications are associated with a recognizable syndrome including intellectual disability and distinctive facial appearance. We report on Xq25 microduplications in two unrelated families identified by array comparative genomic hybridization. In both families, the genomic imbalances segregated with the disease in male individuals, while the phenotypes of the heterozygous females appeared to be modulated by their X-inactivation pattern. These rearrangements of about 600 kb involved only three genes: THOC2, XIAP, and STAG2. Further characterization by FISH analyses showed tandem duplication in the Xq25 locus of these genes. These data refine the Xq25 candidate region, identifying a minimal duplicated region of about 270 kb encompassing the XIAP and STAG2 genes. We discuss the function of the genes in the rearrangements and their involvement in the pathogenesis of this disorder.

Intragenic ILRAPL1 deletion in a male patient with intellectual disability, mild dysmorphic signs, deafness, and behavioral problems.

Intellectual disability affects approximately 2% of the population, with affected males outnumbering affected female, partly due to disturbances involving X-linked genes. To date >90 genes associated with X-linked intellectual disability have been identified and, among these, IL1RAPL1 (interleukin 1 receptor accessory protein-like 1), was first described and mapped to Xp21.3-22.1 in 1999. Intragenic deletions of IL1RAPL1, only rarely identified, have mostly been associated with nonspecific intellectual disability (IDX) and autism spectrum disorder. Array-CGH analysis performed in our patient with intellectual disability, mild dysmorphic signs and changes in behavior identified a 285 Kb deletion in chromosome Xp21.3-21.2, with breakpoints lying in IL1RAPL1 gene intron 2 and intron 3. This is the first patient reported in literature with deletion of only exon 3 of IL1RAPL1 gene. Our patient also exhibits bilateral progressive neurosensorial deafness, which has not been previously associated with IL1RAPL1 mutations.

The 9-bp deletion in region V of mtDNA: a risk factor of hearing loss and encephalomyopathy in Caucasian populations?

A deletion of one of the two copies of the 9-bp tandem repeat sequence (CCCCCTCTA), in the small non-coding/untranslated segment located between the cytochrome oxidase II and lysine tRNA genes of mitochondrial DNA (mtDNA), has previously been used as a polymorphic anthropological marker (MIC9D) for people of Africa and Asia, but it has been rarely reported in Europe. 32 Sicilian patients with syndromic hearing loss, negative for mutations in GJB2 and GJB6 genes, were tested for mtDNA known point mutations associated with syndromic or non-syndromic hearing loss by RFLP and/or direct sequencing. We identified the presence of the MIC9D in homoplasmy in lymphocytes and muscle of three subjects with sensorineural hearing loss and encephalomyopathy, two of these also presented moderate mental retardation. This deletion was absent in 300 Caucasian controls. Although further studies are warranted, our results suggest that the MIC9D polymorphism could have a susceptibility role in Caucasus, such as Sicily population.

Complex segmental duplications mediate a recurrent dup(X)(p11.22-p11.23) associated with mental retardation, speech delay, and EEG anomalies in males and females.

Submicroscopic copy-number variations make a considerable contribution to the genetic etiology of human disease. We have analyzed subjects with idiopathic mental retardation (MR) by using whole-genome oligonucleotide-based array comparative genomic hybridization (aCGH) and identified familial and de novo recurrent Xp11.22-p11.23 duplications in males and females with MR, speech delay, and a peculiar electroencephalographic (EEG) pattern in childhood. The size of the duplications ranges from 0.8-9.2 Mb. Most affected females show preferential activation of the duplicated X chromosome. Carriers of the smallest duplication show X-linked recessive inheritance. All other affected individuals present dominant expression and comparable clinical phenotypes irrespective of sex, duplication size, and X-inactivation pattern. The majority of the rearrangements are mediated by recombination between flanking complex segmental duplications. The identification of common clinical features, including the typical EEG pattern, predisposing genomic structure, and peculiar X-inactivation pattern, suggests that duplication of Xp11.22-p11.23 constitutes a previously undescribed syndrome.

A missense mutation in the coiled-coil domain of the KIF5A gene and late-onset hereditary spastic paraplegia.

BACKGROUND: To our knowledge, up to now, only 2 mutations in the KIF5A gene, a member of the kinesin superfamily, have been identified as the molecular cause of early-onset autosomal dominant hereditary spastic paraparesis (ADHSP). OBJECTIVE: To assess the genetic defect in a family with late-onset ADHSP. PATIENTS AND METHODS: Only the proband agreed to undergo complete neurological testing and mutational analysis. The proband was screened for mutations in the spastin, atlastin, NIPA1, and KIF5A genes, either by denaturing high-performance liquid chromatography or sequence analysis. RESULTS: The history of the family was consistent with ADHSP characterized by late onset of the disease. Mutational analysis results were negative for the spastin, atlastin, and NIPA1 genes but identified a missense mutation (c.1082C>T) in the coiled-coil coding region of the KIF5A gene. CONCLUSIONS: This finding enlarges the phenotypic spectrum of ADHSP linked to KIF5A and enhances the role of that gene in the epidemiology of this disease. We propose that the KIF5A gene should be routinely analyzed in patients with hereditary spastic paraplegia negative for spastin and atlastin mutations.

Quantitative evaluation of partial deletions of the DAZ gene cluster.

Partial deletions of the DAZ gene cluster are thought to cause spermatogenesis impairment. The presence of homologous copies of this gene in the Y chromosome does not allow PCR to be used for the identification of this abnormality. Hence, sequence family variants (SFV), following amplification of sY581, sY587 and sY586 and subsequent enzymatic digestion with Sau3A, DraI and TaqI, respectively, and the dual fiber fluorescence in situ hybridization (FISH) have been used to this aim. However, SFV is not always able to identify single DAZ gene copy deletions. We report a quantitative real-time PCR application to evaluate partial deletions of the DAZ gene cluster. To accomplish this, we designed a probe on exon 6 of the DAZ gene which is repeated 3 times in DAZ1, once in DAZ2 and DAZ3 and twice in DAZ4. Five normozoospermic healthy men (C1-C5) having 4 DAZ gene copies by SFV were selected. Fiber-FISH confirmed this outcome in C1-C4, but not in C5 who had an incomplete DAZ gene cluster. The men underwent then quantitative real-time PCR and C1 was arbitrarily selected as calibrator for the calculation of the DAZ gene signals because of the lowest variation in the threshold cycles. Real-time PCR identified 7.2+/-0.05 signals in C2-C4 and 5.4+/-0.05 signals in C5. The overall coefficient of variation was 1.4+/-0.2%. The loss of two signals in this subject may relate to a deletion of both DAZ2 and DAZ3 or of DAZ4 gene. Since SFV showed clearly the presence of DAZ2, it may be hypothesized that C5 lacks DAZ4. In conclusion, these data suggested that quantitative real-time PCR seems to be an effective and reproducible technique that can be used to study the DAZ gene cluster. In addition, the probe chosen for this approach may give indication on the DAZ gene copy deleted.

Increased FGF3 and FGF4 gene dosage is a risk factor for craniosynostosis.

Interstitial duplications involving chromosome 11q have rarely been reported in the literature and mainly represent large, cytogenetically detectable rearrangements associated with a wide and variable spectrum of neurodevelopmental disorders. We report on a patient affected by intellectual disability, craniosynostosis, and microcephaly. Array-CGH analysis identified a de novo 290 kb interstitial duplication of chromosome 11q13.3 including the FGF3 and FGF4 genes. Clinical comparison of our patient with those previously reported with overlapping 11q duplications allows us to define the minimal duplicated region associated with craniosynostosis and strongly supports the hypothesis that the constitutional increased dosage of the FGF3 and FGF4 genes is a risk factor for craniosynostosis in humans.

6p22.3 deletion: report of a patient with autism, severe intellectual disability and electroencephalographic anomalies.

BACKGROUND: The interstitial 6p deletions, involving the 6p22-p24 chromosomal region, are rare events characterized by variable phenotypes and no clear genotype-phenotype correlation has been established so far. RESULTS: High resolution array-CGH identified 1 Mb de novo interstitial deletion in 6p22.3 chromosomal region in a patient affected by severe Intellectual Disability (ID), Autism Spectrum Disorders (ASDs), and electroencephalographic anomalies. This deletion includes ATXN1, DTNBP1, JARID2 and MYLIP genes, known to play an important role in the brain, and the GMPR gene whose function in the nervous system is unknown. CONCLUSIONS: We support the suggestion that ATXN1, DTNBP1, JARID2 and MYLIP are candidate genes for the pathophysiology of ASDs and ID, and we propose that deletion of DTNBP1 and/or JARID2 contributes to the hypotonia phenotype.

Expression of SPANX proteins in human-ejaculated spermatozoa and sperm precursors.

The sperm protein associated with nucleus in the X chromosome (SPANX) gene family is constituted by only a few members, clustered at Xq27, encoding small proteins which range from 15 to 20 kDa. These proteins have been shown to be present both in mature spermatozoa and in tumours, such as melanoma and some leukaemias. We developed polyclonal sera in order to study the distribution of the protein in human-ejaculated spermatozoa and their precursors. A synthetic peptide was designed from a domain common to the SPANX protein family and polyclonal sera were raised in mice. Seven healthy volunteer men with normal sperm parameters were recruited and the expression of SPANX proteins was evaluated in spermatozoa and ejaculated sperm precursors by immunocytochemistry and immunofluorescence analyses. SPANX proteins, present in a large fraction (96%) of mature spermatozoa, were localized in the sperm head (39.2%), midpiece (22.8%) or in both sites (34.4%). Spermatids also showed the presence of SPANX proteins in their cytoplasm, although a significantly higher number of spermatids were SPANX-negative compared with spermatozoa. In conclusion, SPANX proteins are expressed in an elevated percentage of spermatids and mature spermatozoa. In the latter, they are preferentially located in the sperm head. The greater number of SPANX-negative spermatids observed could relate to their easier exfoliation from the seminiferous tubules.

Morphologically normal spermatozoa of patients with secretory oligo-astheno-teratozoospermia have an increased aneuploidy rate.

BACKGROUND: Normal morphology is a major criterion for selecting spermatozoa to be injected. Given that teratozoospermia is one of the most critical parameters associated with sperm aneuploidy, the purpose of this study was to evaluate the aneuploidy rate of morphologically normal spermatozoa of patients with oligo-astheno-teratozoospermia (OAT). METHODS: Ten patients with secretory OAT and six age-matched normozoospermic men with a normal karyotype were enrolled. After assignment to normal or abnormal category, the location of each spermatozoon was recorded using an electronic microstage locator. Slides were then subjected to triple-colour fluorescence in situ hybridization for chromosomes X, Y and 12. RESULTS: OAT patients had a lower number of morphologically normal and abnormal spermatozoa carrying the X chromosome, compared with normozoospermic men. They also exhibited increased XY and XX disomy rates. Morphologically abnormal spermatozoa from normozoospermic men also had an increased XX disomy rate compared with normally shaped spermatozoa obtained from the same men. The total sperm aneuploidy rate of morphologically abnormal spermatozoa of normozoospermic men was 4.4-fold higher than that of spermatozoa with normal morphology. The total aneuploidy rates of spermatozoa with normal or abnormal head shape from OAT patients were similar to each other and to that of abnormally shaped spermatozoa from normozoospermic men, but they were higher than the rate found in normally shaped spermatozoa of normal men. CONCLUSIONS: Normally shaped spermatozoa of OAT patients have an increased aneuploidy rate.