Preoperative joint line convergence angle correction is a key factor in optimising accuracy in varus knee correction osteotomy.

PURPOSE: This study aimed to identify and prevent preoperative factors that can be influenced in preoperative planning to reduce postoperative malcorrections. METHODS: The method used in this study was a retrospective two-centre analysis of 78 pre and postoperative fully weight-bearing radiographs of patients who underwent valgus osteotomy correction due to symptomatic medial compartment osteoarthritis. A computer software (TraumaCad®) was used to aim for an intersection point of the mechanical tibiofemoral axis (mTFA) with the tibia plateau at 55-60% (medial = 0%, lateral = 100%). Postoperative divergence ± 5% of this point was defined as over- and undercorrection. Preoperative joint geometry factors were correlated with postoperative malcorrection. Planning was conducted using the established method described by Miniaci (Group A) and with additional correction of the joint line convergence angle (JLCA) using the formula JLCA-2/2 (Group B). Additionally, in a small clinical case series, planning was conducted with JLCA correction. Statistical analysis was performed using (multiple) linear regression analysis and analysis of variance (ANOVA) with p < 0.05 considered significant. RESULTS: In 78 analysed cases, postoperative malcorrection was detected in 37.2% (5.1% undercorrection, 32.1% overcorrection). Linear regression analysis revealed preoperative body mass index (BMI, p = 0.04), JLCA (p = 0.0001), and osteotomy level divergence (p = 0.0005) as factors correlated with overcorrection. In a multiple regression analysis, JLCA and osteotomy level divergence remained significant factors. Preoperative JLCA correction reduced the planned osteotomy gap (A 9.7 ± 2.8 mm vs B 8.3 ± 2.4 mm; p > 0.05) and postoperative medial proximal tibial angle (MPTA: A 94.3 ± 2.1° vs B 92.3 ± 1.5°; p < .05) in patients with preoperative JLCA ≥ 4°. The results were validated using a virtual postoperative correction of cases with overcorrection. A case series (n = 8) with a preoperative JLCA > 4 revealed a postoperative accuracy using the JLCA correction of 3.4 ± 1.9%. CONCLUSION: Preoperative JLCA ≥ 4° and tibial osteotomy level divergence were identified as risk factors for postoperative overcorrection. Preoperative JLCA correction using the formula JLCA-2/2 is proposed to better control ideal postoperative correction and reduce MPTA. The intraoperatively realised osteotomy level should be precisely in accordance with preoperative planning. LEVEL OF EVIDENCE: III, cross-sectional study.

Branchio-otic syndrome caused by a genomic rearrangement: clinical findings and molecular cytogenetic studies in a patient with a pericentric inversion of chromosome 8.

Branchio-oto-renal (BOR) syndrome is an autosomal dominantly inherited developmental disorder, which is characterized by anomalies of the ears, the branchial arches and the kidneys. It is caused by mutations in the genes EYA1,SIX1 and SIX5. Genomic rearrangements of chromosome 8 affecting the EYA1 gene have also been described. Owing to this fact, methods for the identification of abnormal copy numbers such as multiplex ligation-dependent probe amplification (MLPA) have been introduced as routine laboratory techniques for molecular diagnostics of BOR syndrome. The advantages of these techniques are clear compared to standard cytogenetic and array approaches as well as Southern blot. MLPA detects deletions or duplications of a part or the entire gene of interest, but not balanced structural aberrations such as inversions and translocations. Consequently, disruption of a gene by a genomic rearrangement may escape detection by a molecular genetic analysis, although this gene interruption results in haploinsufficiency and, therefore, causes the disease. In a patient with clinical features of BOR syndrome, such as hearing loss, preauricular fistulas and facial dysmorphisms, but no renal anomalies, neither sequencing of the 3 genes linked to BOR syndrome nor array comparative genomic hybridization and MLPA were able to uncover a causative mutation. By routine cytogenetic analysis, we finally identified a pericentric inversion of chromosome 8 in the affected female. High-resolution multicolor banding confirmed the chromosome 8 inversion and narrowed down the karyotype to 46,XX,inv(8)(p22q13). By applying fluorescence in situ hybridization, we narrowed down both breakpoints on chromosome 8 and found the EYA1 gene in q13.3 to be directly disrupted. We conclude that standard karyotyping should not be neglected in the genetic diagnostics of BOR syndrome or other Mendelian disorders, particularly when molecular testing failed to detect any causative alteration in patients with a convincing phenotype.

Array CGH in patients with developmental delay or intellectual disability: are there phenotypic clues to pathogenic copy number variants?

Array comparative genomic hybridization (array CGH) is now widely adopted as a first-tier clinical diagnostic test in individuals with unexplained developmental delay/intellectual disability (DD/ID) and congenital anomalies. Our study aimed at enlarging the phenotypic spectrum associated with clinically relevant copy number variants (CNVs) as well as delineating clinical criteria, which may help separating patients with pathogenic CNVs from those without pathogenic CNVs. We performed a retrospective review of clinical and array CGH data of 342 children with unexplained DD/ID. The phenotypic features of patients with clinically significant CNV were compared with those without pathogenic CNVs. Array CGH detected pathogenic CNVs in 13.2% of the patients. Congenital anomalies, especially heart defects, as well as primary microcephaly, short stature and failure to thrive were clearly more frequent in children with pathogenic CNVs compared with children with normal array CGH results. Thus, we assume that in patients with unexplained DD/ID, array CGH will more probably detect a significant CNV if any of these features is part of the patient's phenotype.

A family with an inverted tandem duplication 5q22.1q23.2.

Here, we report a 3-year-old boy with short stature, developmental delay and mild facial dysmorphic signs. Karyotype analysis and array-CGH revealed a pure duplication 5q22.1q23.2 with a length of 14.25 Mb. As demonstrated by multicolor-fluorescence in situ hybridization, the duplicated segment was orientated in an inverted tandem manner. One of the 2 older half-brothers of the index patient was intellectually disabled and showed short stature as well. The mother of the siblings was only 149 cm in height. The affected half-brother as well as the mother of the siblings were tested positive for the same duplication. Duplications of the long arm of chromosome 5 are rare. There are 16 reported cases of different 5q segments with a pure duplication and no additional chromosomal imbalance. In order to refine the 5q-duplication phenotype, reported cases were recently classified in 3 groups on the basis of clinical findings and the involved chromosome segments. However, our case does not fit in any of these groups but is placed in the interjacent chromosomal area between 2 of these groups. Overall, this is the second reported family with a duplication of 5q22.1q23.2 and both families share phenotypic features like short stature, facial dysmorphic signs and speech delay. The reported family provides further information for delineating phenotype-genotype correlations of pure duplications of the 5q region.

Ring chromosome 22 and neurofibromatosis type II: proof of two-hit model for the loss of the NF2 gene in the development of meningioma.

Carriers of a ring chromosome 22 are mentally retarded and show variable facial dysmorphism. They may also present with features of neurofibromatosis type II (NF2) such as vestibular schwannomas and multiple meningiomas. In these cases, tumourigenesis has been suspected to be caused by the loss of both alleles of the NF2 gene, a tumour suppressor localized in 22q12.2. Here, we describe an 18-year-old patient with constitutional ring chromosome 22 and mental retardation who developed rapid-onset spastic paraparesis at the age of 15 years. The causative spinal meningioma at the level of T3, which compressed the spinal cord, was surgically removed, and the patient regained ambulation. Array comparative genomic hybridization (array CGH) and multiplex ligation-dependent probe amplification (MLPA) analyses in blood revealed a terminal deletion in 22q13.32, not comprising the NF2 gene. In tumour tissue, loss of the whole ring chromosome 22 including one NF2 gene due to mitotic instability constituted the likely first hit, while a point mutation in the other allele of the NF2 gene (c.784C>T, p.R262X) was shown as second hit. We review all cases from the literature and suggest clinical guidelines for surveillance of patients with ring chromosome 22.

Is there a yet unreported unbalanced chromosomal abnormality without phenotypic consequences in proximal 4p?

Unbalanced chromosomal abnormalities (UBCA) are reported for >50 euchromatic regions of almost all human autosomes. UBCA are comprised of a few megabases of DNA, and carriers are in many cases clinically healthy. Here we report on a partial trisomy of chromosome 4 of the centromere-near region of the short arm of chromosome 4 present as a small supernumerary marker chromosome (sSMC). The sSMC was present in >70% of amnion cells and in 60% of placenta. Further delineation of the size of the duplicated region was done by molecular cytogenetics and array comparative genomic hybridization. Even though the sSMC lead to a partial trisomy of ~9 megabase pairs, a healthy child was born, developing normally at 1 year of age. No comparable cases are available in the literature. Thus, we discuss here the possibility of having found a yet unrecognized chromosomal region subject to UBCA.

Forty-eight new cases with infertility due to balanced chromosomal rearrangements: detailed molecular cytogenetic analysis of the 90 involved breakpoints.

A molecular cytogenetic study was performed on 48 infertile patients who were identified as carriers of balanced translocations (40 cases), inversions (6 cases) or insertions (2 cases) by means of banding cytogenetics. Cases with a Robertsonian translocation or pericentric inversion 2 or 9 were not included. In summary, 100 break-events occurred in these patients, and 90 different chromosomal regions were involved. Thus, this study confirmed the presence of abnormal karyotypes in a subgroup of patients seeking infertility treatment. Breaks were demonstrated to appear preferentially in GTG-light bands in these patients. Furthermore, the observed breakpoints were associated with genomic regions prone to instability due to the presence of segmental duplications. Nonetheless, further detailed molecular analysis will be necessary in the future to characterize the mechanisms and genetic basis for this phenomenon.

Small supernumerary marker chromosomes (sSMC) in patients with a 45,X/46,X,+mar karyotype - 17 new cases and a review of the literature.

Small supernumerary marker chromosomes (sSMC) can appear in a numerically normal 'basic karyotype', but also in a numerically abnormal one like a Turner syndrome karyotype (= sSMC(T)). Here we present 17 new cases with such a mos 45,X/46,X,+mar karyotype. Moreover we reviewed all 512 cytogenetically similar cases available from the literature and supply for the first time data on occurrence, shapes and subgroups of this rare cytogenetic entity. sSMC(T) are very rare in the common population (1:100,000) - however, they can be observed with a 45- and even 60-times higher frequency in infertile and (develop)mentally retarded patients, respectively. Even though sSMC(T) derive from one of the gonosomes in >99% of the cases, there are also exceptional reports on sSMC(T) derived from one of the autosomes. The majority of sSMC(T)(X) form ring chromosomes, while most sSMC(T)(Y) are inverted duplicated/isodicentric chromosomes. Although >500 sSMC(T) are reported, a detailed characterization of the chromosomal breakpoints is only given for a minority. Thus, more cases with detailed (molecular) cytogenetic marker chromosome characterization are needed to provide information on formation and effects of an sSMC(T).

Prenatal diagnosis of a large de novo terminal deletion of chromosome 11q.

OBJECTIVE: To describe the prenatal phenotype of the 11q deletion syndrome (Jacobsen syndrome) and present the molecular characterization of the deletion in the case presented. CASE: Ultrasound at 18 and 20 weeks of gestation, on a 34-year-old woman who presented for amniocentesis, revealed slow movements, oligohydramnios and dilatation of the cerebral ventricles in the fetus. Maternal and paternal ages were 34 and 38 years, respectively. RESULTS: Prenatal karyotyping of cultured amniotic fluid cells revealed an 11q terminal deletion, 46,XX,del(11)(q23) (Jacobsen syndrome). Real-time quantitative PCR analysis was used to identify and map the breakpoint physically to a 45-kb region located 14.5 Mb from the 11q telomere. Polymorphic DNA marker analysis showed that DNA sequences on the paternally derived chromosome are deleted. At autopsy, facial dysmorphism without major malformations was recorded. Examination of the internal organs disclosed the following abnormalities: a Meckels' diverticulum of 4-mm length, adhesion between the gall bladder and the transverse colon, and bilaterally bilobed lungs without further situs anomalies. CONCLUSION: Our case demonstrates significant phenotypic variability of Jacobsen syndrome at midtrimester pregnancy; the syndrome may be manifested at this stage only by mild to moderate ventriculomegaly of the brain.

Association of Jacobsen syndrome and bipolar affective disorder in a patient with a de novo 11q terminal deletion.

We report on a young woman with Jacobsen syndrome (JBS) who was admitted to our psychiatric department because of a bipolar affective disorder (BPAD). Chromosome analysis was performed due to the fact that she had mental retardation, short stature, and subtle facial anomalies. A deletion of the distal long arm of chromosome 11 was found. A detailed mapping of the deletion breakpoint by quantitative real time PCR revealed a true terminal 11q deletion of approximately 8 Mb corresponding to the karyotype 46,XX,del(11)(q24.2). Polymorphic DNA marker analysis showed that the deletion is located on the paternal chromosome. Additionally, laboratory investigations revealed a low platelet count and magnetic resonance imaging of the brain showed white matter T2 hyperintensities in frontotemporal regions, which are unlikely to result from a demyelinating process as indicated by localized proton magnetic resonance spectroscopy. To our knowledge, this is the first report describing a BPAD in a case with JBS.

Molecular cytogenetic characterization of a de novo supernumerary ring chromosome 7 resulting in partial trisomy, tetrasomy, and hexasomy in a child with dysmorphic signs, congenital heart defect, and developmental delay.

We report on a girl with mosaicism (65%) of a de novo supernumerary ring chromosome 7. The main clinical features were delayed psychomotor development, congenital heart defect, facial dysmorphisms, and long hands, fingers, feet and toes. Molecular cytogenetic analysis revealed that the ring chromosome was duplicated in 20% of the analyzed metaphases with marker chromosome and quadruplicated in 5% thereof. Uniparental disomy (UPD) of the two normal sister chromosomes 7 was excluded. This is, to our knowledge, the first report of a partial tetrasomy to hexasomy due to a ring chromosome 7. Additionally, the ring evolution could be reconstructed according to the FISH-results.

Fetal alcohol syndrome in association with Rett syndrome.

Fetal alcohol syndrome in association with RETT syndrome: We report on a girl with neonatal dystrophy, microcephaly, heart defect, and the characteristic features of alcohol embryopathy. Later, she developed distinctive features of RETT syndrome including loss of early acquired developmental skills and presented typical symptoms of RETT syndrome as reduction of communication skills, reduction of hand function, hyperventilation, and grinding of teeth. Molecular analysis of the MECP2 gene revealed the c.808T>C (R270X) mutation located in the nuclear localisation signal sequence of the gene. Our report highlights the importance of considering the diagnosis of RETT syndrome even in patients who are already suffering from a defined disease.

First non-mosaic case of isopseudodicentric chromosome 18 (psu idic(18)(pter --> q22.1::q22.1 --> pter) is associated with multiple congenital anomalies reminiscent of trisomy 18 and 18q- syndrome.

Isopseudodicentric chromosome 18 is very rare and results in a combination of partial trisomy and partial monosomy of chromosome 18. We report here a hypotrophic newborn with a lateral cleft lip and palate and multiple craniofacial dysmorphisms, a combined heart defect, unilateral hypoplasia of the kidney, bilateral aplasia of thumbs, and generalized contractures. Cytogenetic analysis revealed an isopseudodicentric chromosome 18 with breakpoint in 18q (46,XX,psu idic(18)(pter --> q22.1::q22.1 --> pter)). The isopseudodicentric chromosome 18 was observed in 100% of blood lymphocytes and umbilical cord fibroblasts, thus indicating a non-mosaic finding of the isopseudodicentric chromosome in the child. An elongated derivative chromosome 18 had also been found prenatally in amniotic cells. In contrast, a terminal deletion (18q-) was detected in placental cell cultures. The breakpoint was mapped to a 0.9 Mb region on 18q22.1 (located 64.8-65.7 Mb from the telomere of the p-arm) by a novel quantitative PCR approach with SYBR green detection. The results indicate an identical breakpoint of the isopseudodicentric chromosome 18 in the child and the 18q- chromosome in the placenta. To our knowledge this is the first report that a fetus carrying an isopseudodicentric chromosome 18 with breakpoint in 18q (46,XX,psu idic(18)(pter --> q22.1::q22.1 --> pter)) in non-mosaic form can be viable, but is associated with severe congenital malformations of the child.

Supernumerary small marker chromosome (SMC) and uniparental disomy 22 in a child with confined placental mosaicism of trisomy 22: trisomy rescue due to marker chromosome formation.

Trisomy rescue is one of various proposed mechanisms in formation of supernumerary small marker chromosomes (SMC) and uniparental disomy (UPD). In the present report a small de novo marker chromosome derived from chromosome 14 or 22 was diagnosed at prenatal diagnosis due to maternal age. Follow up investigations at birth revealed mosaicism 47,XX,+mar/46,XX. Using FISH, the marker was positive for the probe D14/22Z1, but negative for the probes midi 54 and D22Z4. Using three informative markers both chromosomes 22 were shown to be inherited from the mother (UPDmat). The results are consistent with nondisjunction at maternal meiosis I. The girl is 18 months old now and phenotypically normal. Cardiac and abdominal malformations were excluded by sonographic examinations. Motor and mental development is according to or ahead of developmental milestones (free walking with 10 months, first words at 12 months). The case confirms that maternal UPD 22 most likely is not associated with clinical abnormalities. According to FISH results, UPD 22, and 47,XX,+22 in the placenta, we conclude that the SMC was derived from alpha satellite sequences of chromosome 22. This case for the first time gives evidence that early postzygotic reduction of a chromosome to a small marker chromosome is a real existing mechanism to rescue a conceptus with trisomy.

A phenotypically normal liveborn male after prenatal diagnosis of trisomy 20 mosaicism.

We report on a case of prenatally diagnosed true trisomy 20 mosaicism in amniocytes. Cytogenetic analysis was performed postnatally on lymphocytes and extra-embryonic tissues. For analysing uroepithelial cells we established a new cell nuclei preparation protocol for FISH (Fluorescence In Situ Hybridization). Trisomy 20 cells could not be confirmed after birth. The origin or trisomy 20 cells in amniotic fluid remains unclear. The phenotypically normal male baby is developing normal.

A novel family-specific translocation t(2;20)(p24.1;q13.1) associated with recurrent abortions: molecular characterization and segregation analysis in male meiosis.

In the present study, we present a novel reciprocal translocation t(2;20)(p24.1;q13.1) and its segregation in a three generation family. The rate of miscarriages (50%) in pregnancies from male translocation carriers could be explained by unbalanced translocation-bearing spermatozoa found with a frequency of approximately 55% in the entire sperm population of a t(2;20)(p24.1;q13.1) carrier. These imbalanced spermatozoa mainly present as 2, der(20) and der(2), 20 missegregated (approximately 46%) while adjacent 2 and 3:1 segregation patterns account for approximately 5% and 4% of imbalances, respectively. While the translocation is associated clearly with an increased risk of early abortions (7/12) in both male and female carriers, no malformed livebirths were observed. Our results suggest complete embryonic lethality of imbalanced offspring. With respect to a high rate of segregation to 2, der(20) and to der(2), 20 imbalanced spermatozoa in male translocation carriers and with respect to known cases of partial trisomy 2p and 20q we consider that their corresponding monosomies result in fetal loss. This is the first study reporting multiple abortions associated with partial monosomy 20q13.1-->qter and 2pter-->p24.1 and the first report on the frequency of chromosomal imbalances in gametes of a male t(2;20)(p24.1;q13.1) heterozygote.

Additional dark G-band in the p-arm of chromosome 19 due to a paracentric inversion with a breakpoint in the pericentromeric heterochromatin.

Paracentric inversions in chromosome 19 have rarely been described. Here we present an inv(19)(p11p13.1) with a breakpoint in the pericentromeric heterochromatin which leads to an additional dark G-band in the p-arm of chromosome 19. The rearranged chromosome segregated in two generations of a family without any phenotypic effects. A detailed characterization of the inv(19) by molecular cytogenetic techniques is presented.

Short stature in a mother and daughter caused by familial der(X)t(X;X)(p22.1-3;q26).

Deletions of the terminal Xp regions, including the short-stature homeobox (SHOX) gene, were described in families with hereditary Turner syndrome and Léri-Weill syndrome. We report on a 10-2/12-year-old girl and her 37-year-old mother with short stature and no other phenotypic symptoms. In the daugther, additional chromosome material was detected in the pseudoautosomal region of one X chromosome (46,X,add(Xp.22.3)) by chromosome banding analysis. The elongation of the X chromosome consisted of Giemsa dark and bright bands with a length one-fifth of the size of Xp. The karyotype of the mother demonstrated chromosome mosaicism with three cell lines (46,X,add(X)(p22.3) [89]; 45,X [8]; and 47,X,add(X)(p22.3), add(X)(p22.3) [2]). In both daughter and mother, fluorescence in situ hybridization (FISH), together with data from G banding, identified the breakpoints in Xp22.1-3 and Xq26, resulting in a partial trisomy of the terminal region of Xq (Xq26-qter) and a monosomy of the pseudoautosomal region (Xp22.3) with the SHOX gene and the proximal region Xp22.1-3, including the steroidsulfatase gene (STS) and the Kallmann syndrome region. The derivative X chromosome was defined as ish.der(X)t(X;X)(p22.1-3;q26)(yWXD2540-, F20cos-, STS-, 60C10-, 959D10-, 2771+, cos9++). In daughter and mother, the monosomy of region Xp22.1-3 is compatible with fertility and does not cause any other somatic stigmata of the Turner syndrome or Léri-Weill syndrome, except for short stature due to monosomy of the SHOX gene.