Chance of Having a Dwarf Child

What are my chances of having a baby with dwarfism?

We frequently see incoming search queries related to people asking questions such as What are the chances of having a dwarf baby? and Do dwarf parents always have dwarf children? Since there is a lot of interest in this topic, here is our attempt at making this understandable. (A quick reminder: dwarf or little person is the preferred term, not midget).

Autosomal Dominant Disorders

These types of dwarfism only require one parent to pass on the gene (or through a random mutation at conception). Some examples are achondroplasia, pseudoachondroplasia, hypochondroplasia, and SEDc.

Two Average Height Parents (no history of dwarfism)

  • Approximately 1 in 25,000 (0.004%) chance of a child with dominant dwarfism

Average Height parent and Parent with Achondroplasia

  • 50% chance of child without dwarfism
  • 50% chance of child born with Achondroplasia

Two parents with Achondroplasia

  • 25% chance of average height child
  • 50% chance of child born with Achondroplasia (heterozygous Achondroplasia)
  • 25% chance of homozygous Achondroplasia and is not compatible with life

1 Parent has Achondroplasia, 1 Parent has Pseudoachondroplasia

  • 25% chance of child without dwarfism
  • 25% chance of child with Achondroplasia
  • 25% chance of child with Pseudoachondroplasia
  • 25% chance of child with Achondroplasia AND Pseudoachondroplasia

Can two average height parents have two children with Achondroplasia?

Surprisingly, the answer is yes and it’s very rare. We’re not geneticists, but our high-level understanding is that while most mutations for dwarfism occur at conception, it’s possible that a parent can have a mutation in the precursor cells to the sperm and egg. Therefore, a parent can give multiple children a gene that already has the mutation even though the parent themselves does not have Achondroplasia (it’s called germline mosaicism).

Autosomal Recessive Disorders

These types of dwarfism require both parents to pass on the gene in order to be affected. If a person has only one copy of the gene, they are considered a carrier but not affected and can pass the gene onto their child. Some examples are Diastrophic Dysplasia and Cartilage-Hair Hypoplasia.

Two Average Height Parents (no history of dwarfism and not a carrier)

  • Approximately 0% chance of a child with recessive dwarfism

Two Average Height Parents (carriers for Diastrophic Dysplasia)

  • 25% chance of child without dwarfism
  • 50% chance of child is a carrier for Diastrophic Dysplasia
  • 25% chance of child with Diastrophic Dysplasia

Two parents with Diastrophic Dysplasia

  • 100% chance of child with Diastrophic Dysplasia

Average Height (non-carrier) Parent and Parent with Diastrophic Dysplasia

  • 100% chance of child without dwarfism and carrier for Diastrophic Dysplasia

Average Height (carrier) Parent and Parent with Diastrophic Dysplasia

  • 50% chance of child is a carrier for Diastrophic Dysplasia
  • 50% chance of child with Diastrophic Dysplasia

Dwarfism Book

If you would like to learn more about dwarfism, check out the Dwarfism Book by Betty Adelson.

Did we miss a possibility you’re interested in or get something wrong? Please let us know!

Comments 35

  1. We have an elder daughter 26. We have a son 24 with achondroplasia.. Both me Nad wife are normal no history in family. Daughter is normal… What is the prognosis fro daughters off springs if she marries a normal boy..

    1. In cases like yours where your son is the only one with Achondroplasia, he is the dominant carrier of the gene (FGFR3). Like most dominant types of dwarfism, Achondroplasia is a sporadic mutation. Your Average Height daughter’s chances of having a child with any type dwarfism is the same as any one else in the general population.

      As a point of clarification, the term is average height for a person without dwarfism, not “normal”.

  2. Two Average Height Parents (no history of dwarfism and not a carrier)
    Approximately 0% chance of a child with recessive dwarfism

  3. My parents and all extended family (that we know of) are average height. I am the second of 4 children, and I have SEDc. My sister (the 4th of 4) also has SEDc, but my brothers (1st and 3rd children) do not.

    Sounds to me that your statistic of “Two Average Height Parents (no history of dwarfism and not a carrier) Approximately 0% chance of a child with recessive dwarfism” may be wrong, as this is exactly my sister and my situation.

    1. “Can two average height parents have two children with Achondroplasia?
      Surprisingly, the answer is yes and it’s very rare. We’re not geneticists, but our high-level understanding is that while most mutations for dwarfism occur at conception, it’s possible that a parent can have a mutation in the precursor cells to the sperm and egg. Therefore, a parent can give multiple children a gene that already has the mutation even though the parent themselves does not have Achondroplasia (it’s called germline mosaicism).”

    2. Were your parents tested as carriers (possessing one affected gene but showing no phenotype)? If they were tested and were found not to be carriers then this is a really rare case! Definitely not a 0% chance of happening but certainly unlikely.

  4. Hi

    My boyfriend Is of normal height but Both his parents and his brother have achondroplasia. I am of normal height with no family history of achondroplasia.
    What are the chances of my partner and I having a child with dwarfism? Would he be a “carrier “? Even tho he is not affected by it?

    1. You have just as much chance as anyone else in the world to have a child with Achondroplasia as the gene is only carried within the person with that gene (FGFR3). His parents and brother have the dominant gene. They have a 50% chance of having a child with Achondroplasia and a 25% chance of having an Average Height child.

      If you have any further questions, you can discuss this with an experienced geneticist like the ones on the LPA Medical Advisory Board.

  5. My husband has two brothers who have achondroplasia…his parents, he himself and his other siblings are of normal stature…what is the prognosis for the achondroplasia brothers offsprings if they get married to their first cousins?

  6. Hi my mom is average height my dad has acon.I have a con and so does.my two brothers.My dad’s brothers all where normal height and his dad and mom where to.Does this mean that somewhere in are family tree that there could have been more and does this every skip a generation Thank you Mike

  7. My dad is the last and the tenth child in their family and the only dwarf to his parents who are both average heights.
    My mom is also average height and their marriage gave life to five children:
    1-boy (average height)
    2-girl (dwarf)
    3-boy ME(average height)
    4-boy (dwarf)
    5-boy (average height)

    my oldest brother (the first child-average height) married another woman with average height and has two daughters both with average height.

    my sister (the second child- dwarf) and my younger brother (the 4th child- Dwarf) both decided to not risk it and have any babies.

    I (the 3rd child-average height) is going to marry a girl with average height. what are the chances that my babies become dwarf? I am the only child that has inherited spots and benign moles from my father in exact forms and places that my dad has. does it mean that dwarfism gene is strong in me?

    1. I have a similar situation, I am of average height with no family history.

      My husband of average height was born from his father of average height, and his mother with achondroplasia. My husband has two other siblings, of the 3 only one was affected.
      I now am pregnant with my husband of average height and curious to hear what our percentage of chances could be?

      1. Not very high chances. Achondroplasia has full penetrance meaning that you can’t have the gene and not have dwarfism. If your husband does not have achondroplasia then he is not a carrier- if you had a child with achondroplasia it would be because of a new random mutation. The chances of that are pretty low and are associated with advanced paternal age (older fathers).

  8. My mother has achondroplasia. There was no history of it in the family before so i’m assuming there was a sporadic mutation. I’m her first child and i’m of average height. I have a baby on the way and the mother has no history of dwarfism in her family either. What are the chances of the child being affected with the condition?

  9. me and my wife are normal. We have a son with achondroplasia. Our 2nd pregnant is ectopic. Now my wife has 3rd pregnancy. What are the chances of having achondroplasia child?

    1. Mosaicism is rare, but it can happen. If the possibility of having another child with dwarfism affects your decision in having another child, we suggest talking to the two Geneticists on the LPA Medical Advisory Board (Dr. Hoover-Fong and Dr. Krakow).

  10. What are my chances to have a dwarf child if my mother was a dwarf, my father was not, I am not, and my partner is not?

  11. Hi my husband and I normal, we had a baby and he had, Thanatophoric dysplasia dwarfism . We dont have any family member who were dwarfs before, What was the cause of it? he sadly he passed on 3 weeks ago.

  12. She has just as much chance as anyone else to have a child with Achondroplasia as your son is the carrier of the gene (FGFR3) and not your daughter. FGFR3 is a dominant not recessive gene.

  13. Hello . My husbands brother has achondroplasia , what are the chances of our children having it . He is of average height . Would it be 25% or 50%?

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