ChromosOmics - Database
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                        TL/sSMC-book.jpg tl_files/tiny_templates/Bilder
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                                                                           - START -                                                                         
>6.670 cases included
last update: 01.01.2020 

How to cite this database:
Liehr T. 20
XXSmall supernumerary marker chromosomes.
http://cs-tl.de/DB/CA/sSMC/0-Start.html [accessed XX/XX/XXXX]
[VG-Wort (bc0e9794c01a456786cbeefcd0a83fc1)]
COUNTER

in 2019: 3280
 in 2018: 3900
 in 2017: 3230
 ~3000 visitors per anno
(since 2014)

Created by Dr. Thomas Liehr (PhD)
professional affiliation: Institute of Human Genetics, 07740 Jena, Germany;
e-mail: Thomas.Liehr@med.uni-jena.de or: LiehrT@web.de


origin calculator (sSMC-OC)
cases included there are marked with °°°;
sSMC-syndrome related symptoms were taken from literature


At present we are looking for patients / families with Cat-Eye-syndrome
who would be willing to support a project aiming to identify such patients
just by facial image - if you are willing to help please click here



AIM OF THIS PAGE PROBLEMS ACHIEVEMENTS ACKNOWLEDGMENTS
Patient and unser information
Information for families
(in 25 languages)
Patient organizations How to use this page
Abbriviations
BASIC INFORMATION ON sSMC
What are sSMC? What do sSMC do? First description of sSMC
eu- and heterochromatin mosaicism uniparental disomy
other names for sSMC frequency of sSMC formation of sSMC
sSMC BY CHROMOSOME
sSMC
1
sSMC
2
sSMC
3
sSMC
4
sSMC
5
sSMC
(1
)/5/19
sSMC
6
sSMC
7
sSMC
8
sSMC
9
sSMC
10
sSMC
11
sSMC
12
sSMC
13
sSMC
13/21
sSMC
14
sSMC
14/22

sSMC
16
sSMC
17
sSMC
18
sSMC
19
sSMC
20
sSMC
21
sSMC
22
sSMC
X
sSMC
Y
sSMC
acro
sSMC
non-acro
sSMC
multiple
sSMC
McCl
sSMC
Ps.McCl


sSMC +
autos.
sSMC +
gonos.
46/sSMC
X/Y/?
Else Kröner-Fresenius-cellbank for small supernumerary marker chromosomes
in short: Else Kröner-Fresenius-sSMC-cellbank

FOR CLINICIANS AND CYTOGENETICIST
Managing an 'sSMC-case'? FISH-probes for sSMC submit your case
DISCLAIMER

links helpful for diagnostics:


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References

Aim of this page

1. collect all available case reports on small supernumerary marker chromosomes (sSMC)

2. define critical regions for partial trisomies due to the presence of sSMC

3. provide information for patients and clinicians

4. offer possibility to characterize sSMC in detail

contact Dr. Thomas Liehr, Jena, Germany: Thomas.Liehr@med.uni-jena.de

Problems when an sSMC is detected

According to {70} there are several reasons for the difficulty
to relate clinical syndromes to the occurrence of sSMC:

1. sSMC chromosomes can be derived from each of the 24 human chromosomes.

2.
Even if two sSMC originate from the same chromosome, they still often differ in size and in the
content of euchromatic material from either or both arms of a chromosome.

3.
Structural variants of sSMC, e.g., ring formation, have been described.

4. Some patients have multiple sSMC of same or different origin.

5. Single or multiple sSMC often occur in a mosaic form.

6. Silent euchromatin duplication are described - what about silencing in sSMC? {111}

7.
4/10, 16/46 or even 38/45 sSMC could not be characterized by array-comparative genomic hybridization (aCGH)!! {176; 178; 187}
Rate is up to 90% in infertile  sSMC carriers {186}.

8. Also next generation sequencing is not really suited to characterice sSMC {178; 184}

Further information on centromeres see Refs: {154-155}

Please take care that the nomenclature here is not always done acc. to ISCN !!

Achievements

Here an up-to-date page is presented, which provides:

- a collection of all published sSMC by chromosome

- genotype-phenotype-correlation for centromere-near chromosomal imbalances

- a collection of all published cases with uniparental disomy (UPD), as UPD is also a problem relevant in sSMC

-
a collection of all heterochromatic variants

- sSMC basic data in 25 languages

- the possibility to submit an sSMC case to the collection

- a book on sSMC (available since November 2011)

- FDNA project - help geneticists identify patients with small supernumerary marker chromosomes earlier.
First paper on that see {185}.


Acknowledgments from patients and clinicians (anonymized)

From USA (2018)
Thank you so much for all your help you are giving me hope!

From Germany (2017 - translated)
Thank you for taking the time to gather information and explain it to me so well. That is not self-evident. You helped us a lot with this!

From Greece (2016)
Thank you so much for responding to my mails!!! You already made me feel better!!!!!


From USA (2015)
I thought you might like to see a picture of my gorgeous little girl born 3 years ago. Looking at her now I can’t believe the mental state I
was in during the pregnancy. You and your work made a big difference for her and our family.

From USA (2014)
It is not possible to stress how important your website/database was for me when I needed information. I think it is quite important that it is maintained.

From Spain (2014)
Thank you again for it.
We can only be grateful to you and your team for the rapidity with which it has sent the report.
Now we can not put into words the happiness we feel and how grateful we are to you. We are eternally grateful.
Our best wishes to you and good luck with your research and hard work.


From UK (2012):
We so appreciate your professional excellence and kind sensitivity in
supporting us so closely through this.

From Italy (2012):
Thanks a lot for your friendly support and qualified subject-specific guidance supporting us on our not that easy way to come to a decision concering our actual pregnancy.

From China (2010):
Thank you so much for the detailed answers, it gives us even more confidence on the upcoming baby!Many thanks again and wish you all the best as well.

From USA (2009):
Thanks a lot for your response. We will definitely consult you in the future if needed. Again, we deeply appreciated your help.
Wish you the best in your research,
which is certainly very important for parents like us.

From USA (2007):
My husband and I can't thank you enough for all the time you have spent on our case. We so appreciate all you have done to help us to get through this difficult and unsure time. We have looked at your website many times and are trying to figure out which markers are most similar to ours. …And again, I so appreciate all your efforts on our case - not just your testing, but your attention and advice.

From Germany (2007 - translated):
Thank you very much indeed for your quick response and support. It is good to known to have someone giving support in this situation. We hope that many expectant parents will profit in future from your work and dedication, as well.

From Germany (2006 - translated):
What started with a lot of doubts and worries in this spring now in autumn had a happy end. This week our daughter was born. She is healthy, wide-awake and certainly gorgeous. We are relieved and overjoyed.
We want to thank you again for your quick and straightforward help and assure that your mail-contacts were extremely helpful to deal with the uncertainty.

From UK (2006):
Thank you very much. I greatly appreciate your help with this case.

Patient and user information

Here some layman explanations on this page can be found:
We provide those explanations in 25 different languages.


The group of Dr. Liehr in Jena, Germany presently characterizes (on request) sSMC from all over the world (Thomas.Liehr@med.uni-jena.de).

We already characterized sSMC of carriers from
Europe: Armenia, Austria, Belarus, Belgium,  Croatia, Cyprus, Denmark, France, Greece, Great Britain, Hungary, Italy, Montenegro, Poland, Portugal, Romania, Russian Federation, Spain, Switzerland, Serbia, Slovakia, Slovenia, Turkey, Ukraine.

Africa: Egypt, Morocco, South-Africa, Taiwan, Tunisia, .

Asia: China, India, Israel, Jordan, Korea, Lebanon, Saudi Arabia, Sri Lanka, Taiwan.

America: Canada, Equador, Uruguay, USA.

Australia: Australia, New Zealand.

What do sSMC?

  In 74% of the cases a de novo sSMC has no phenotypic effects! {156}
 
In 1974 it was postulated "that a bisatellited chromosome by association with acrocentric chromosomes
may interfere with mitosis at a critical stage of fetal development" {22}
Of prenatally ascertained cases with sSMC the following percentage shows abnormal phenotypes: 18% of 33 cases {13}; 30% of 27 cases {42}; 13% of 123 cases {43}
The overall risk for abnormal phenotype is 10.9% for cases with satellited sSMC and 14.7% for cases with non-satellited sSMC {43}
The risk of an abnormal phenotype associated with a de novo sSMC (excluding those derived from chromosome 15) is 7% (if sSMC is from 13, 14, 21 or 22) and 28% (for non-acrocentric chromosomes) {44}
44% of prenatally ascertained cases with sSMC are familial cases {42}
First report on a 3 generation sSMC without clinical effect described in {71}
 "The phenotypes associated with the presence of a marker vary from normal to severely abnormal." {66}
It is discussed that sSMC may lead to reduced fertility in males without additional clinical symptoms in connection with the sSMC {57; 65; 69; 90}
Of 123 cases with sSMC detected prenatally between 1970 and 1989 in USA 37 were electively terminated, while only 4 of the remaining 86 pregnancies ended with a still birth or spontaneous abortion. 9 additional cases of the 86 cases were born with abnormalities (= 10.5%) {43}
 In {160} in 1/2 prenatally detected sSMC the MOM of ßC-hCG:Cr was reduced to 0.31 and in both cases the MOM of free ß-hCG:Cr was enhanced to ~1.5.
In one male with normal sperm (normozoospermia) sSMC present in 26% of sperm and 42% of fertilized embryos {168}
sSMC have a yet not in detail understood influence on spermatogenesis {179; 180}

For clinicians and cytogeneticists

In case you want to submit an already studied, unpublished sSMC case for the database  please use this form
The laboratory of Dr. Thomas Liehr is willing to help characterizing sSMC cases from all over the world.
After arrival in our lab a report will normally be issued for prenatal cases within 5 working days and for postnatal cases within 2-4 weeks.
Please feel free to contact us via Thomas.Liehr@med.uni-jena.de or efwkliehr@yahoo.com.


Also, the laboratory of Dr. Thomas Liehr provides different FISH-probes for characterization of sSMC to coworking laboratories.



Suggestions for a kind of ideal sSMC management
(adapted from {76})

1. an sSMC is detected
2. test parents for sSMC presence
3. check for sSMC's chromosomal origin by molecular cytogenetics
    (if appropriate also apply aCGH; i.e. only in case of no low mosaicism)
    also consider possibility of discontinous sSMCs
4. if appropriate and indicated check for UPD of the sister chromosomes of sSMC
5. especially in case of unusual sSMCs establish a cell line

 

Frequency of sSMC - according to their chromosomal origin
(based on this page)

N.B. 1: in case of cryptic mosaicism of the sSMC, the shape the most frequently occurring variant is included in the following table.
N.B. 2: discontinous sSMC and such with UPD not specifically listed in summary.

chr. centric minute rings inv dup / i / idic neocentric McCl/ markers

SUM

simple complex simple complex simple complex clinical tumor PsMcCl unspec
1 32 - 54 - 1 - 7
1 3 / 1 15 114
2
27 - 27 - 2 - 2 - 3 / 1 12 74
3
23 - 13 - 1 - 12 4 1 / - 4
58
4 19
2 14 - 1 - 1 - 5 / - 5
47
5 35
- 13 - 37 - 3 - 2 / -
11
101
6 13 - 7 - 1 - 3 - 4 / -
1
29
7 21 1 15 - 1 - 4
- 2 / -
7
51
8 55 3 49 - 23 - 15 - 1 / -
16 162
9 31 5 17 - 118 - 3 1 2 / 2
8 187
10 17 1 6
- 1
- 1 -
2 / -
4
32
11 16 1 9
1 - - - - 2 / 1
8 38
12 20 2 12
- 768 - 6 -
1 / -
4 813
13 10
13
4
- 4
- 21 -
3 / 2
3
60
14 32
19
8 - 120 - - - 1 /  1
22 203
15 66
17 32
- 1180 4 32 - 1 /  1
160 1493
16 42 - 24 - 3
- 2 - 1 /  1
23 96
17 30
1
10
- 2
- - - 1 / 2
3
49
18 28 6
17
- 355
- 2 - - / 2
20 430
19 38 1
33 - 2
- 1 - 1 / -
10
86
20 27
- 20
- 4 - 1 - - / 1
11 64
21 30 13 8
- 12 - - - - / -
7
69
22 38
430 11
- 415 4 - - 2 / -
18 918
X 18 - 19
- - - 2 - 2 / -
3
46
Y
6
- 5
- 8
- 3 - - / -
3
25
X
(in 46 chrs.)
50
- 146
- 1 - - - - / -
32 229
Y
(in 46 chrs.)
18
- 67
- 313 - - - - / -
45
443
no X/Y
(in 46 chrs.)
1
- - - - - - - - / -
3
4
13 or 21 17 8 4 - 101 3
- - 1 / -
31 165
14 or 22 14 1 - - 27 - - - - / -
41
83
(1)/5/19 7
- 2 - - - - -
- / -
3
12
acro - - - - 8 - 3 - - / -
121 133
non-acro - 3 - - - - - - - / -
32 35
aut-aneusomy
11 1
4
- 18
2
- - - / -
24
60
gon-aneusomy 8 - 2
- 5
- - - - / -
4
19
multiple 101
1 65
1 10 - 1 - - / -
75
254
SUMMARY 901 530
717
2
3542
13
125 6
41 / 15 789
6682
chr. simple complex simple complex simple complex clinical tumor McCl/ unspec.

SUM

centric minute rings inv dup / i / idic neocentric PsMcCl markers





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