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BY Annie

13 chromosomal disorders you may not have heard of

You’ve heard of Downs syndrome and Fragile X syndrome, but what about Jacobsen syndrome? Or 22q11.2 deletion syndrome?

In this post we bring attention to some lesser known chromosomal disorders.

If your child has one of these conditions please share your experiences with us in the comments below.

1. Wolf-Hirschhorn syndrome

Description: Wolf-Hirschhorn syndrome is caused by the deletion of the distal short arm of chromosome 4. The disorder’s major features include a characteristic facial appearance, delayed growth and development, intellectual disability, and seizures.
Organizations promoting awareness: The Real Story About Wolf-Hirschhorn Syndrome
In the news: Living With Wolf-Hirschhorn Syndrome

2. Jacobsen Syndrome

Description: Jacobsen syndrome, also known as 11q deletion disorder, results from a loss of genetic material from the end of the long arm of chromosome 11. Signs and symptoms of this condition vary, but most individuals experience delayed development in motor skills and speech, cognitive impairments, learning difficulties, and some behavioral problems.
Organizations promoting awareness: 11q Research & Resource Group
In the news: Thousands raised for Jacobsen Syndrome

3. Angelman syndrome

Description: Angelman syndrome (AS) is an example of genomic imprinting, where the deletion or inactivitation of genes on the maternally inherited chromosome 15 causes the paternal copy, which may be of normal sequence, to be imprinted and silenced. AS is characterized by intellectual and developmental delays, sleep disturbances, seizures, and jerky movements, but also frequent laughter or smiling and usually have a happy demeanor.
Organizations promoting awareness: F.A.S.T &  Angelman Foundation, Inc.
In the news: In Depth: Angelman Syndrome

4. Turner syndrome

Description: Turner syndrome (TS) occurs when one of the two X chromosomes in females is either missing or incomplete. The most common symptoms are short stature and gonadal dysgenesis, which can cause incomplete sexual development and ovarian failure and infertility. As of right now, there is no known cause of TS.
Organizations promoting awareness: Turner Syndrome Society of the US
In the news: Family spreads awareness of Turner syndrome

5. 22q11.2 deletion syndrome

Description: 22q11.2 deletion syndrome is caused by the deletion of a small piece of chromosome 22 near the middle of the chromosome. Because signs and symptoms of 22q11.2 deletion syndrome are varied, different groupings of symptoms were once described as completely separate conditions, named DiGeorge syndrome, velocardiofacial syndrome, and conotruncal anomaly face syndrome.
Organizations promoting awareness: The International 22q11.2 Deletion Syndrome Foundation, Inc.
In the news: 22q11.2 deletion syndrome conference to bring together researchers, educators, families

6. Triple X Syndrome

Description: Triple X Syndrome is characterized by an extra X chromosome in each of a female’s cells. It does not cause any unusual physical features but is associated with the increased risk of learning disabilities and delayed development of speech and language skills.
Organizations promoting awareness: Triple X Syndrome
In the news: What Is Triple X Syndrome? What Causes Triple X Syndrome?

7. Williams Syndrome

Description: Williams syndrome is caused by a deletion of genetic material from portions of the long arm of chromosome 7, a region that consists of more than 25 genes. Researchers have identified a few of the specific genes related to Williams syndrome, but the relationship between most of the genes in the deleted region and the symptoms of Williams syndrome is still unknown.
Organizations promoting awareness: Williams Syndrome Association
In the news: Williams syndrome shows gene-behavior links: Key to autism?

8. Cri du Chat Syndrome

Description: Cri du Chat syndrome results from missing a piece of chromosome 5. Symptoms include a high-pitched cry that sounds like a cat, downward slant of the eyes, partial webbing or fusing of fingers or toes, and slow or incomplete development of motor skills.
Organizations promoting awareness: Five P Minus Society
In the news: ‘Cat Cry’ Syndrome Often Undiagnosed

9. Trisomy 13/Patau syndrome

Description: Trisomy 13, also called Patau syndrome, is a disorder in which an individual has three copies of genetic material from chromosome 13, rather than two. It can occur in three forms: Trisomy 13, which has a third chromosome 13 in all cells; Trisomy 13 mosaicism, which has a third chromosome 13 in some cells; and partial Trisomy, which has the presence of part of an extra chromosome 13 in the cells.
Organizations promoting awareness: Living With Trisomy 13
In the news: Sequenom Validates MaterniT21 for Trisomy 18 and 13 Detection

10. Trisomy 18/Edwards syndrome

Description: Trisomy 18, or Edwards syndrome, occurs when a person has a third copy of material from chromosome 18 instead of the usual two copies. Some symptoms include clenched hands, feet with a rounded bottom, mental deficiency, underdeveloped fingernails, and an unusual shaped chest.
Organizations promoting awareness: Trisomy 18 Foundation
In the news: Baby Jalyssa’s Story: Fighting The Odds, Living With Edward’s Syndrome

11. Cat eye syndrome

Description: For individuals with cat eye syndrome, the short arm (known as 22p) and a small region of the long arm (22q) of chromosome 22 are present three or four times, rather than twice. Characteristic features of the  disorder include mild growth delays before birth, mild mental deficiency, and malformations of the skill and facial region, the heart, the kidneys, and/or the anal region.
Organizations promoting awareness: Support for Disorders of Chromosome 22
In the news: Blog: “Our Journey with Cat Eye Syndrome

12. Trisomy 16

Description: Full Trisomy 16 occurs when an individual has three copies of chromosome 16 instead of the usual two and is the most common chromosomal cause of miscarriage during the pregnancy’s first trimester. Mosaic Trisomy 16 is a rare disorder in which an extra chromosome 16 is present in some cells, but not all. Some common symptoms include intrauterine growth retardation (IUGR) and congenital heart defects.
Organizations promoting awareness: Disorders of Chromosome 16
In the news: Trisomy 16: the Leading Cause of Miscarriage

13. Charcot-Marie-Tooth disease

Description: Charcot-Marie-Tooth (CMT) disease is the most common inherited neurological disorder and is caused by genetic mutations. CMT1A results from a duplication of the gene on chromosome 17 that carries instructions for producing the peripheral myelin protenin-22.
Organizations promoting awareness: Charcot-Marie-Tooth Association
In the news: Disease Cause Is Pinpointed With Genome

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13 chromosomal disorders you may not have heard of


Written on May 22, 2012 by:

Annie is currently a junior journalism major at Michigan State University. She is an associate editor for ing Magazine, a student-run magazine on campus, and manages ing's Twitter, Facebook and Tumblr accounts. Annie has spent her last three summers at camp working with children who have special needs. When she is not on Twitter or blogging, she likes to dance, swim, and read as many books as humanly possible.
  • Usagi_21

    Actually trisomy 18 is on the rise. In fact 1 in every 3,000 live births will be a trisomy 18 or 13 child. There is no known reason behind it, it’s a medical fluke. Being a mother of a Child that had trisomy 18 as diagnose there have been over 100+ persons that I have met on fb or at children’s hospital here in washington that have children diagnosed with a Trisomy condition. Trisomy doesn’t discriminate it can happen to anyone, any age, race or background.

    • Thewritingowl

      The trouble here in Ireland is that you cannot even get the Health Services to just refer your child for a proper Fragile X test never mind something as specific as these other conditions. After almost a year of constant bombardment I still don’t even know if my four year old son who has already been diagnosed with Autism and Developmental delay has these conditions because he is carrying the FXS gene. I really suspect he is as I myself have Aspergers Syndrome also. Also I have an older daughter. We really are still living in the dark ages here in Ireland. If anyone out there can help me get my son tested or just advise me then that would be great.

  • My daughter has a chromosome 14 deletion. There is very little written about it. I would love to have any information anyone may have on it.

    • Samantha Lindsay

       Since I do not have specifics of the location of the deletion the best I can do for you is give you the list of registered abnormalities with Unique… they are in numerical order so please scroll down to Chromosome 14 and hopefully you’ll find something there useful for yourself!

  • Jena

    My advice to parents of children diagnosed with these chromosomal abnormalities is to go beyond all the doom and gloom written about these children through medical websites.  Instead, reach out for support from people in similar situations.  My niece is full Trisomy 18, diagnosed at birth.  We were told she would never make it home from the hospital.  Then she was sent home with hospice care to keep her comfortable for whatever limited life she may have.  Then we celebrated her first birthday…and 11 others since then.  She will be 13 years old in November, that is 4,745 days longer than all the experts said she’d live, and she’s still going strong.  There is hope for these children and support for these families, especially through SOFT- Support Organization For Trisomy 18 and Related Disorders,

  • Michelle Galloway

    Here’s one you missed:  A lot of people don’t know about 22q11.2 deletion, true, but the awareness is on the rise.  Even less people know about the 22q11.2 duplication syndrome.  My son, my sister & myself all have it.  It’s similar to the deletion, but in most cases it’s inherited as opposed to de novo & causes a lot of the same issues as does the deletion but has a few features of it’s own as well.

  • Hopeforvanessaandjacob

    Both of my children have duplication chr 14q32.33 we are told the are the first known case of it so no one knows anything about it.

    • Netbuddy Tips

      Have you contacted Unique? –  They have a leaflet on distal 14q duplications.  My daughter has a larger terminal duplication from 14q31.  Also has cri du chat syndrome.  Would love to hear more about your children.  Emma Joy – Netbuddy

  • Trisomy 8 Mosaic syndrome, Warkany syndrome.  My granddaughter has it.  She was the first baby they had at the Medical College of Georgia to be diagnosed with it.  I have found ONE doctor in the US that has seen 2 cases.

  • Mommypilot

    Alfi’s Syndrome Chromosome 9p minus 

  • BlueJeansandLace

    My son is a “one of a kind” with three abnormalities, none of which are known (one has a little literature but no clear path) The hardest part is that we don’t know what to expect. Funny because when they thought they knew what it was, we thought that was the hardest part. Their doom and gloom vrs our having no idea. Rough either way. So we just do the best we can.

    7q11.22 Dup
    12q24.32 Dup
    16p13.11 (Del)

    • Tlj913

      My son has a rare chromosome disorder too. His is a chromosome 1 microduplication.. the hardest part for me too is the uncertainty and not knowing what to expect as far as health and development are concerned. I get a lot of anxiety over it, but like you, I can only do the best I can and see what happens next. Good luck to you and your family..I know how it is.

    • Samantha Lindsay

      (7q Dups)

      (12q Dups)


      • BlueJeansandLace

        Thank You. The only one that really covered any of it was for the 16p. And not even that totally fits. *shrug* Now if only they could find the answers for someone with the mix!

  • BlueJeansandLace

    My son is a “one of a kind” with three abnormalities, none of which are known (one has a little literature but no clear path) The hardest part is that we don’t know what to expect. Funny because when they thought they knew what it was, we thought that was the hardest part. Their doom and gloom vrs our having no idea. Rough either way. So we just do the best we can.

    7q11.22 Dup
    12q24.32 Dup
    16p13.11 (Del)

  • Alicia noe

    My daughter Madelyn has single copy loss of 10 oligonucleotide probes from long arm of chromosome 13 and a single copy gain of  X chromosome. We were told that she is one of only 5 in the world that they know of. She is a very happy girl but we do deal with a lot of medical problums. Having her in our life shows us how much there is to be happy about I look at my little girl and say if she can go through all this in her life then I can get through anything in mine. I have high hope’s that maddy will be what ever she wants to be when she gets older nothing can stop her!

  • guest

    My son was diagnosed with XY/XO mosaicism by amniocentesis, early in my 2nd trimester of pregnancy. When he was 4-5 years old, we had him re-tested (military “lost” the medical records). No sign of mosaicsm. He has other issues related to Rh incompatability (the original concern for which we had the amnio), but not this. Sometimes an amnio will catch the discarded cells. My son is still “special needs”. My advice to someone who has just received an abnormal amnio or ultrasound, though, is to never trust a single test to determine your course of action. I hope all the best for those of you living with these conditions! 

  • Pingback: 8th Biennial International 22q11.two Deletion Syndrome Meeting « Easy Dental Health & Tooth Whitening()

  • M_kolis

    Have a student with 2q37 deletion syndrome… almost nothing printed about this as well…

    • Samantha Lindsay

  • Tammiejo

    Check out WAGR/ 11p Deletion Syndrome !

  • Klga052601

    It’s great your article includes CMT 1A. Thank you

  • Acfshenk

    Thank you for spreading awareness about these rare conditions! Our son has Prader-Willi syndrome, which involves the 15th chromosome. It is likely more common than a lot of the conditions listed above, but most people we run across have not heard of it. If you would like to read more about PWS, check out

    • Tzvi

      Your very welcome! Thanks for sharing about Prader-Willi Syndrome.

  • Guest

    I have Mosiac Turners Syndrome. I have 1 and a half X chromosomes.I am short(4’11 adult height) but have none of the phsyical signs such as a webbed neck or learning delay.So far I am devolping normally for a 14 year old.Infertility may be in my future but i will see what that holds.An important thing to note is people with any chromosmal abnormality especially Turner’s,Down Syndrome and William’s Syndrome are at an increased risk for Celiac Diesese.I have Celiac.

  • My Brothers Keeper

    My younger brother has 21 DEL He is 5 years old. He is short for his age and recives OT,PT and speech therapies.

  • Chriszeiner1998

    Our little 3 year old girl has 3 abnormalities, all duplications.
    12q24.11, 12, and 13
    17q25.1, 2 and 3

    I completely agree about not knowing what the future holds, keep working and hope for the best. I will say our little girl is about as happy and full of life as you can get. Just delayed in nearly everything, she is growing on her own curve.

  • Samantha Lindsay

    One of my twins was diagnosed with 16p11.2 Microdeletion Syndrome when she was 9 months old. You can read about it on Disorders of Chromosome 16’s website…. The discovery of it was published in 2008 so there is still a lot of learning to be done. Some of the “most common” effects of this is Macrocephaly (large head), Obesity (often times beginning in early childhood), Developmental Delay, Autism Spectrum Disorders (1 in 100 with this microdeletion are believed to also be on Autism Spectrum), Language Delays (articulation being the biggest area of delay), and Seizures. The Simons VIP Foundation is actively researching the deletion and duplication of the 16p, they are a wonderful foundation! 

  • Mel

    My Sister has XXXY chromozones, I don’t know if there is a proper name for it at all. So little is known about her condition that when she was little the doctors said that she wouldn’t make it to 20… she is now 37 years old and is healthy and happy. She does have severe mental disabilities and can never function in an unsupervised environment.

  • Marie McLaughlin

    I have a son who was diagnosed in 2007 with Chromosome 1: q24-25 deletion disorder. I am told that he is extremely rare as, at that time, only 8 persons with this disorder were located in the world. My sone is now 40 years old.
    He seems to be a smattering of characteristics from various disorders. He has chronic on-going ear and sinus infection. Had multiple blood coagulation problems which have now been addressed with medication. He has a variety of characteristics/ behaviors that are on the Autism spectrum. I am most concerned with his unpredictable episodes of physically and verbally aggressive behavior. We have had little-to-no success in finding a medication which can help him in this area. I really would like to hear from anyone having a child with this diagnosis and would especially like to know if anyone is having any success in dealing with the behavior issues.

  • stacy madden

    My son has Fragile X syndrome. The number one leading cause of autism.

  • Bethany Burton

    My son is 6 year old and has a missing 5 chromosome deletion has trouble gaining weight and learning disabilities.does anybody have the same thing

  • Priscilla

    Hello! We have fertlity issues.Lately,we have done ivf with pgd screening cycle.It seems that the chromosome 20 has mosaic duplication 20 p ” mosaic aneuploid”
    Can you give us plz an explanation ? Is this embryo transferable or not??


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