Trisomy Disorders

Archive for September 2009

Abnormal growth in noonan syndrome: the challenge of optimal therapy. 

Savage MO, Padidela R, Kirk JM, Malaquias AC, Jorge AA.

Department of Endocrinology, Barts and the London School of Medicine and Dentistry, London, UK. m.o.savage@qmul.ac.uk

Noonan syndrome (NS) is a phenotypically heterogeneous condition frequently associated with short stature. Genetic investigations have identified mutations in several genes, e.g.PTPN11, KRAS, RAF and SOS1 in patients with the NS phenotype and related disorders such as LEOPARD, Costello and Cardiofacio- cutaneous syndromes. In NS, PTPN11 mutations are present in 29-60% of cases. The degree of short stature does not associate closely with the presence of a mutation; however, some PTPN11-positive patients have decreased growth hormone (GH)-dependent growth factors consistent with mild GH insensitivity. GH therapy induces short-term increases in height velocity over 1-3 years, and is likely to improve adult height.

PMID: 19550387 [PubMed – indexed for MEDLINE]

Successful fertility treatment for Klinefelter’s syndrome.


J Urol. 2009 Sep


Ramasamy R, Ricci JA, Palermo GD, Gosden LV, Rosenwaks Z, Schlegel PN.
Center for Reproductive Medicine and Infertility, New York-Presbyterian Hospital, Weill Cornell Medical College, New York, New York.


PURPOSE: We examined preoperative factors that could predict successful microdissection testicular sperm extraction in men with azoospermia and nonmosaic Klinefelter’s syndrome. We also analyzed the influence of preoperative hormonal therapy on the sperm retrieval rate.


MATERIALS AND METHODS: A total of 91 microdissection testicular sperm extraction attempts were done in 68 men with nonmosaic Klinefelter’s syndrome. Men with serum testosterone less than 300 ng/dl received medical therapy with aromatase inhibitors, clomiphene or human chorionic gonadotropin before microdissection testicular sperm extraction. Preoperative factors of patient age and endocrinological data were compared in those in whom the procedure was and was not successful. The sperm retrieval rate was the main outcome. Clinical pregnancy (pregnancy with heartbeat) and the live birth rate were also calculated.


RESULTS: Testicular spermatozoa were successfully retrieved in 45 men (66%), representing 62 (68%) attempts. Increasing male age was associated with a trend toward a lower sperm retrieval rate (p = 0.05). The various types of preoperative hormonal therapies did not have different sperm retrieval rates but men with normal baseline testosterone had the best sperm retrieval rate of 86%. Patients who required medical therapy and responded to that treatment with a resultant testosterone of 250 ng/dl or higher had a higher sperm retrieval rate than men in whom posttreatment testosterone was less than 250 ng/dl (77% vs 55%). For in vitro fertilization attempts in which sperm were retrieved the clinical pregnancy and live birth rates were 57% and 45%, respectively.


CONCLUSIONS: Microdissection testicular sperm extraction is an effective sperm retrieval technique in men with Klinefelter’s syndrome. Men with hypogonadism who respond to medical therapy may have a better chance of sperm retrieval.

ScienceDirect

Herron: Down syndrome an oft misunderstood disorder
By Mason Herron / Columnist
published: Tue, 15 Sep, 2009

When we reflect upon the progress humanity has made, we often reach two conclusions: praise for the progress and the heroes that brought it and the realization of how much more progress must be made. Historically speaking, there are a plethora of examples to this law: colonialism, religious tolerance, civil rights, gender equality, etc.

You get the idea. Perhaps, then, we might consider these reflections and apply them to an issue of today that might not be as eminent but is nonetheless in dire need of grave reflection and consideration, and that is the way we perceive the nature of Down syndrome.

Down syndrome — also referred to as trisomy 21 — is a disorder brought on by the presence of an additional chromosome in an individual’s genes. People who have the disorder are typically developmentally disabled and display below-average cognitive ability. Physical characteristics include low muscle tone, almond-shaped eyes, a flat nasal bridge, a protruding tongue and a number of other features. Each individual might experience these characteristics with different intensities and variability.Down syndrome occurs in one of every 800 births, and the risk of conceiving a child with Down syndrome increases as women grow older, with women older than 35 having 80 percent of Down syndrome births.
 Our understanding of Down syndrome — and the way it was portrayed — was, until recently, simple at best and cruel at worst. The disorder was popularly referred to as “mongolism” (in reference to a Mongoloid race), and the term still creeps its way into modern medical texts. Worse, however, was the implementation of a policy in the early 20th century by 33 of 48 states that mandated that individuals with Down syndrome be forced to undergo involuntary sterilization, and many were murdered by Nazi Germany’s “Action T4” euthanasia program.

This history reveals not only a lack of ethics in regard to the mentally disabled, but also a severe underestimation of the capabilities of those who are born with Down syndrome. A generation after many of those with Down syndrome would have been institutionalized, many are able to happily live and work independently. Many are also perfectly literate, and I hope I need not point out the remarkable athletic talent and leadership displayed at Special Olympics events across the country.

But then one reads this: “It is crucial to reaffirm the morality of aborting a fetus diagnosed with Down syndrome … Because a person afflicted with Down syndrome is only capable of being marginally productive (if at all),” Nicholas Provenzo, founder of the Center for the Advancement of Capitalism, said.

Perhaps no one has said it better than online blogger, Diana Hsieh. “[Christians] would regard abortion as a moral way to prevent the infliction of a miserable, degraded life on the person that will emerge from the womb. Instead, they want to create more mentally defective and perpetually dependent children by outlawing abortion.”

A 2002 study revealed that 91 to 93 percent of Down syndrome pregnancies were intentionally terminated. Many potential parents are unwilling to take on the burdens and uncertainties of raising a disabled child. However, these fears are often exacerbated by a misunderstanding of Down syndrome. According to a congressional testimony by Dr. Brian Skotko, mothers included in his study that had been diagnosed as having a Down syndrome pregnancy “reported that doctors did not tell them about the positive potential of people with Down syndrome, nor did they feel like they received enough up-to-date information or contact information for parent support groups.”

Efforts have been made to rectify this concern. The bi-partisan Prenatally and Postnatally Diagnosed Conditions Awareness Act, signed by President Bush in October 2008, is a bill that seeks to inform and educate the public about Down syndrome and other prenatally or postnatally diagnosed disorders. Fortunately, government has not been the only instrument used toward the proliferation of information regarding Down syndrome. Many organizations, including the National Association for Down Syndrome, the National Down Syndrome Society and the Down Syndrome Association of Pittsburgh, have done work to educate others about this condition, as well.

It seems our immediate impressions of people often get the best of us. In the eyes of some, those with Down syndrome live an incomplete life, an unfair life. Yet we must realize this is not always the case and that those with Down syndrome shouldn’t be defined by their disorder. By willfully changing our perceptions on this particular issue, we take a step toward contributing to the progress of humanity as a whole.

E-mail Mason at mph20@pitt.edu.

PittNews


Molecular genetic analysis of Down syndrome.

Hum Genet. 2009 Jul

Patterson D.
Eleanor Roosevelt Institute, University of Denver, 2101 E. Wesley Avenue, Denver, CO 80208-6600, USA. dpatter2@du.edu

Down syndrome (DS) is caused by trisomy of all or part of human chromosome 21 (HSA21) and is the most common genetic cause of significant intellectual disability. In addition to intellectual disability, many other health problems, such as congenital heart disease, Alzheimer’s disease, leukemia, hypotonia, motor disorders, and various physical anomalies occur at an elevated frequency in people with DS. On the other hand, people with DS seem to be at a decreased risk of certain cancers and perhaps of atherosclerosis. There is wide variability in the phenotypes associated with DS. Although ultimately the phenotypes of DS must be due to trisomy of HSA21, the genetic mechanisms by which the phenotypes arise are not understood. The recent recognition that there are many genetically active elements that do not encode proteins makes the situation more complex.

Additional complexity may exist due to possible epigenetic changes that may act differently in DS. Numerous mouse models with features reminiscent of those seen in individuals with DS have been produced and studied in some depth, and these have added considerable insight into possible genetic mechanisms behind some of the phenotypes. These mouse models allow experimental approaches, including attempts at therapy, that are not possible in humans. Progress in understanding the genetic mechanisms by which trisomy of HSA21 leads to DS is the subject of this review.

SpringerLink


Triple-marker prenatal screening program for chromosomal defects.

Obstet Gynecol. 2009 Jul

Kazerouni NN, Currier B, Malm L, Riggle S, Hodgkinson C, Smith S, Tempelis C, Lorey F, Davis A, Jelliffe-Pawlowski L, Walton-Haynes L, Roberson M.
Genetic Disease Screening Program, California Department of Public Health, Richmond, California, USA. neely.kazerouni@cdph.ca.gov

OBJECTIVE: To examine screening performance of California’s triple-marker screening program, using data from a statewide registry for chromosomal defects.

METHODS: This study included 752,686 women who received a screening risk and had an expected date of delivery between July 2005 and the end of June 2007. Follow-up diagnostic services for screen-positive women were performed at state-approved centers. Data on diagnostic outcomes from these visits were entered into the California Chromosomal Defect Registry (CCDR). Other CCDR sources include mandatory reporting by all cytogenetic laboratories and hospitals and outcome data forms submitted by prenatal care providers. RESULTS: The observed detection rate for Down syndrome (N=1,217) was 77.4%. It varied significantly by gestational dating method and maternal age. The rates for women aged younger than 35 years and 35 years and older were 62.4% and 94.0%, respectively. The detection rates were 81.3% for ultrasound-dated pregnancies and 67.5% for last menstrual period-dated pregnancies. For Turner syndrome, trisomy 18, triploidy, and trisomy 13, the detection rates were 79.4%, 82.5%, 98.1%, and 36.0%, respectively. The positive rate for Down syndrome was 5.4%. Of women with a Down syndrome fetus who were screen positive, only 49.5% opted for amniocentesis. Of women who obtained results from amniocentesis indicating a Down syndrome fetus, 61.4% had an elective termination, 26.2% had a live birth, 4.5% had a death or miscarriage, and 7.9% had an unknown outcome.

CONCLUSION: The observed performance of this large triple-marker screening program exceeds generally predicted detection rates for Down syndrome. This study methodology will be used to measure the performance of subsequent screening enhancements.

Lippincott, Wilkins & Williams

Language development impairment and trisomy 8 mosaicism
 

Klinik und Poliklinik für Phoniatrie und Pädaudiologie, Medizinische Hochschule Hannover, Hannover, Germany. Ptok.Martin@mh-hannover.de

Constitutional trisomy 8 mosaicism (46,XX/47,XX,+8 or 46,XY/47,XY,+8) is characterized by trisomic distribution of chromosomes in some but not all cells of the body. The full condition presents with physical stigmata, skeletal abnormalities and a mild to moderate cognitive impairment.Here we present a boy aged 3 years 10 months with partial trisomy 8 who was referred because of a language impairment. Because of known anomalies (corpus callous agenesis, deformities of the spine) a chromosomal analysis was initiated.This case highlights the necessity for an interdisciplinary diagnostic approach in children with language impairment and other constitutional disorders

Springer Link


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