Loss of heterozygosity on chromosome 22 in sporadic schwannoma and its relation to the proliferation of tumor cells

Background Schwannoma is the tumor arising mainly from the cranial and spinal nerves. Bilateral vestibular schwannoma is the hallmark of neurofibromatosis type 2 （NF2）. The NF2 gene has been cloned with comprehensive analysis of its mutations in schwannoma. However, most studies focused on vestibular schwannoma. There are differences in proliferation of tumor cell and uhrastructure between vestibular and spinal schwannomas. It is unknown whether genetic alterations in vestibular schwannoma are different from those in non-vestibular schwannoma. We analyzed the loss of heterozygosity （LOH） on chromosome 22 in patients with sporadic schwannoma including vestibular and spinal schwannomas and correlated this genetic alteration with tumor proliferation. Methods In 54 unrelated patients without clinical NF1 or NF2, 36 patients had sporadic vestibular schwannoma, and 18 dorsal spinal root schwannoma. Four highly polymorphic linkage to NF2 gene microsatellite DNA markers （D22S264, D22S268, D22S280, CRYB2） were used to analyze LOH. The proliferative index was evaluated by Ki-67 and proliferative cell nuclear antigen （PCNA） immunostaining. Student＇s t test was used to analyze the difference of the proliferative index between schwannoma with LOH and that without LOH. The difference of the frequency of LOH in vestibular and spinal schwannomas was investigated by the chi-square test. Results Twenty-three schwannomas （42. 6% , 23/54） showed allele loss. The frequency of LOH in vestibular schwannoma was significantly higher than that in spinal schwannoma （ X^2 = 5.14, P 〈 0.05 ）. The proliferative index of schwannoma with LOH was significantly higher than that without LOH （tki-67 = 2. 97, P= 0. 0045 ; tPCNA =2.93, P =0. 0051）. Conclusions LOH on chromosome 22 is a frequent there is a correlation between LOH on chromosome 22 event in the tumorigenesis of sporadic schwannoma. And, and proliferative activity in schwannoma. The frequency of LOH in vestibular schwannoma is significantly different from that in spinal schwannoma.

Detailed Deletion Mapping of Chromosome 9p21-22 in Nasopharyngeal Carcinoma

Objective: To further refine the extent of deletion on chromosome 9p21-22 in nasopharyngeal carcinoma (NPC) and provide evidence for discovering new tumor suppressor gene. Methods: Loss of heterozygosity (LOH) on chromosome 9p21-22 was analyzed in 25 paired blood and tumor samples by using 11 high-density microsatellite polymorphic markers. Results: 17 of 25 cases (68.0%) showed LOH at one or more loci. Higher frequencies of LOH were found at four loci: D9S161 (35.0%), D9S1678 (31.5%), D9S263 (33.3%) and D9S1853 (33.3%), where 6 cases had a contiguous stretch of allelic loss. Conclusion: The minimal common region of deletion might be defined between D9S161 and D9S1853 (estimated about 2.7 cM in extent) at 9p21.1, suggesting that inactivation of one or more tumor suppressor genes located in this region may be an important step in NPC.

Constructing Molecular Marker Linkage Maps of Chromosome 14Sh and 22Sh and QTL Mapping for Major Traits by Use of Substitution Lines of Gossypium hirsutum L.

CSB14Sh,which is isogenic for its recurrent parent TM-1 except for chromosome 14 short arm,was crossed with TM-1,and the F2 population was produced.A total of 3800 SSR primer pairs covering the whole genome were used to screen polymorphism among two parents,TM-1 and CSB14Sh,

Use of amniocytes for prenatal diagnosis of 22q11.2 microdeletion syndrome： a feasibility study

Background A study of prenatal genetic diagnosis for 22q11.2 microdeletion, which has a wide phenotypic spectrum that involves almost all organs, is rarely reported in China. This study aimed to explore the prevalence of 22q11.2 microdeletion in congenitally malformed fetuses via the fluorescent in situ hybridization （FISH） technique and to investigate the feasibility of use of amniocytes to diagnose 22q11 .2 microdeletion syndrome prenatally. Methods The study enrolled 23 cases of fetal cardiac malformation, as indicated by ultrasound in Beijing Anzhen Hospital and 14 cases of non-cardiac malformation, as determined by type-B ultrasound in Beijing Anzhen Hospital and other hospitals. Amniotic fluid was obtained by amniocentesis before odinopoeia, and the stillborn fetuses of the induced labor were preceded to autopsy. The amniotic fluid of 20 cesarean deliveries during the same period of time was used as a control. The TUPLE1 gene in the amniotic fluid of malformed and normal fetuses was assessed by the FISH method. Results The prevalence rates of the TUPLE1 gene deletion in the amniotic fluid cells from fetuses with cardiac deformations and fetuses without such malformations were 43.5% and 57.1%, respectively. The deletion of TUPLE1 was significantly associated with fetal malformation. Conclusion Chromosome 22q11.2 microdeletion is one of the major factors leading to fetal congenital malformations, and prenatal FISH screening for 22q11 .2 microdeletion syndrome is technically feasible using amniocytes.

A DiGeorge Syndrome Case Report—Challenges of Diagnosis and Management

Background: DiGeorge syndrome (also known as velo-cardio-facial syndrome) is a rare multisystem genetic disorder occurring in approximately 1 in 4000 to 1 in 6000 live births [1]. Although advances in genetic screening have improved diagnosis in developed countries, the condition remains underdiagnosed in developing nations such as the Republic of Moldova, where access to genetic testing and family planning services is limited. Routine prenatal screening usually includes regular ultrasounds, monitoring of blood pressure, complete blood counts, coagulation studies, glucose, urine protein, and urine culture. Current ultrasound techniques have limitations in detecting this syndrome due to variability in interpretation, and genetic testing is often performed based on clinical discretion. The ultrasound could potentially point towards a genetic problem, as in DiGeorge, if multiple cardiac malformations are spotted in utero, but most cases such as this one are diagnosed after birth while being described as totally normal on prenatal ultrasound. Purpose: This study aims to highlight the diagnostic challenges and the need for comprehensive evaluation in identifying DiGeorge syndrome, emphasizing the importance of considering the syndrome as a whole rather than focusing on isolated organ system issues. Method: We present a case report of a 6-month-old girl who, after an uneventful pregnancy and normal prenatal ultrasound, presented with cardiac insufficiency. Following extensive investigations and multiple surgical interventions, DiGeorge syndrome was diagnosed at 9 months of age. Results: The patient’s diagnosis was delayed due to the lack of prenatal markers and the reliance on separate investigations of affected organ systems. Despite several interventions aimed at managing her symptoms, the final diagnosis was made after observing the association of multiple clinical features and conducting comprehensive genetic testing. Conclusions: This case underscores the importance of a holistic approach to diagnosis, which involves a thorough patient history, integration of diverse diagnostic tests, and recognition of the syndrome’s multi-system nature. It highlights the necessity for improved diagnostic protocols and increased awareness in regions with limited access to advanced genetic testing to prevent delays in identifying DiGeorge syndrome and to facilitate timely and appropriate management.