Medical Genetics · Joubert syndrome

Chance of Having Another Child with Joubert Syndrome

At a Glance

If you have a child with Joubert syndrome, there is typically a 25% chance in each subsequent pregnancy that the next child will also have the condition due to autosomal recessive inheritance. Genetic testing and counseling can help families understand their specific risks and family planning options.

If you already have a child diagnosed with Joubert syndrome, the chance that your next child will also have the condition is typically 25% with each pregnancy ^[1]^[2]^[3]. This specific risk depends on the genetic inheritance pattern in your family.

Understanding the Genetics

Joubert syndrome is a genetic condition. In most families, it is passed down in an autosomal recessive pattern ^[1]^[2]^[3].

Autosomal Recessive Inheritance: We inherit two copies of most genes—one from each parent. In autosomal recessive inheritance, both parents are “carriers” of a genetic change (mutation) that causes Joubert syndrome. Carriers do not have symptoms because their other copy of the gene works normally. When two carriers have a child together, there is a 1 in 4 (25%) chance in every pregnancy that the child will inherit the mutated gene from both parents and have Joubert syndrome ^[1]^[2]^[3].
X-Linked Inheritance (Rare): In a very small number of cases, Joubert syndrome is caused by a change on the X chromosome, specifically involving the OFD1 gene ^[4]^[5]. Because males only have one X chromosome, they will have the condition if they inherit the mutated gene. If a mother carries an X-linked mutation, there is a 50% chance in each pregnancy that her son will have Joubert syndrome ^[4]^[5]. Daughters have a 50% chance of inheriting the mutation and becoming carriers themselves, though they are usually asymptomatic ^[4].

To know your exact chances, genetic testing is used to identify the specific genetic cause in your affected child ^[6]^[7]. However, in a small percentage of families, the exact gene mutation cannot be found despite comprehensive testing ^[8]^[9]. If the gene remains unidentified, doctors typically assume a 25% recurrence risk based on the high probability of autosomal recessive inheritance, though your family planning options will change ^[9]^[10].

Family Planning Options

Because every family’s genetic profile is unique, meeting with a genetic counselor or a maternal-fetal medicine specialist is an essential first step. They can help coordinate testing and explain which of the following options apply to your situation.

If the specific gene changes causing Joubert syndrome in your family have been identified, you have several options:

Preimplantation Genetic Testing (PGT-M): If you choose to undergo In Vitro Fertilization (IVF), you can use PGT-M to test embryos for the specific gene mutation before they are implanted into the uterus ^[11]^[12]. This option significantly lowers the chance of passing on the condition ^[13]^[14]. While effective, IVF combined with PGT-M is a significant physical, emotional, and financial undertaking ^[12]^[15].
Prenatal Genetic Testing: If you are already pregnant, or plan to conceive naturally, you can choose to have genetic testing during pregnancy. Procedures like Chorionic Villus Sampling (CVS) or amniocentesis test the baby’s DNA for the known gene mutation ^[16]^[9]. It is important to note that these are invasive procedures that carry a very small risk of miscarriage ^[16].

If the specific gene mutation cannot be identified in your affected child, targeted DNA tests like PGT-M or CVS cannot be used. Instead, monitoring will rely on:

Prenatal Imaging: Doctors can use advanced fetal ultrasound and fetal MRI to look for the “molar tooth sign”—a distinct brain structure difference that is a hallmark of Joubert syndrome ^[16]^[10]. These brain differences typically become visible on imaging around the mid-second trimester (18 to 22 weeks) ^[16]^[17]. While imaging is helpful, the molar tooth sign can sometimes be subtle or absent, making imaging less definitive than genetic testing ^[18]^[16].

Common questions in this guide

What are the chances of having a second child with Joubert syndrome?

If both parents are carriers of an autosomal recessive mutation, there is a 25% chance with each pregnancy that the child will have Joubert syndrome. In rare X-linked cases, mothers have a 50% chance of passing the condition to a son.

Can we test an embryo for Joubert syndrome before pregnancy?

Yes, if the specific gene mutation in your family is known, you can use preimplantation genetic testing (PGT-M) combined with IVF. This allows doctors to test embryos for the mutation before they are implanted in the uterus.

What are our options if the exact genetic cause of our child's Joubert syndrome is unknown?

If the specific gene mutation cannot be identified, targeted DNA tests like PGT-M or CVS cannot be used. Instead, your care team will rely on advanced prenatal imaging like fetal MRI in the second trimester to monitor the baby's brain development.

What is the molar tooth sign they look for during pregnancy?

The molar tooth sign is a specific, distinct brain structure difference that is a primary characteristic of Joubert syndrome. It can often be detected using fetal ultrasound or fetal MRI between 18 to 22 weeks of pregnancy.

Curated prompts to bring to your next appointment.

1.Has the specific gene mutation responsible for my child's Joubert syndrome been successfully identified?
2.Based on our child's test results, what is the exact inheritance pattern (autosomal recessive or X-linked) for our family?
3.What are the current wait times and processes for creating a custom PGT-M probe for our family's specific mutation?
4.If we conceive naturally, what are the safety risks versus benefits of a CVS procedure compared to amniocentesis for our specific situation?
5.Who in our hospital network should perform our fetal MRI to ensure they have the most expertise in detecting the molar tooth sign?

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References (18)

1
Whole exome sequencing reveals novel CEP104 mutations in a Chinese patient with Joubert syndrome.
Luo M, Cao L, Cao Z, et al.
Molecular genetics & genomic medicine 2019; (7(12)):e1004 doi:10.1002/mgg3.1004.
PMID: 31625690
2
Joubert Syndrome with Orofacial Digital Features.
Bhardwaj P, Sharma M, Ahluwalia K
Journal of neurosciences in rural practice 2018; (9(1)):152-154 doi:10.4103/jnrp.jnrp_338_17.
PMID: 29456362
3
Whole exome sequencing identified a novel missense alteration in CC2D2A causing Joubert syndrome 9 in a Pakhtun family.
Khan MI, Latif M, Saif M, et al.
The journal of gene medicine 2021; (23(1)):e3279 doi:10.1002/jgm.3279.
PMID: 32989887
4
Novel OFD1 frameshift mutation in a Chinese boy with Joubert syndrome: a case report and literature review.
Zhang K, Meng C, Ma J, et al.
Clinical dysmorphology 2017; (26(3)):135-141 doi:10.1097/MCD.0000000000000183.
PMID: 28505061
5
A novel pathogenic variant in OFD1 results in X-linked Joubert syndrome with orofaciodigital features and pituitary aplasia.
Aljeaid D, Lombardo RC, Witte DP, Hopkin RJ
American journal of medical genetics. Part A 2019; (179(6)):1010-1014 doi:10.1002/ajmg.a.61018.
PMID: 30895720
6
Clinical and genetic spectrum from a prototype of ciliopathy: Joubert syndrome.
Aksu Uzunhan T, Ertürk B, Aydın K, et al.
Clinical neurology and neurosurgery 2023; (224()):107560 doi:10.1016/j.clineuro.2022.107560.
PMID: 36580738
7
Joubert Syndrome in Children-A Comprehensive Analysis of Quality of Life, Functional Independence and Family Impact.
Elmaoğlu E, Coşkun AB, Usgu S, et al.
American journal of medical genetics. Part A 2025; (197(12)):e64213 doi:10.1002/ajmg.a.64213.
PMID: 40750754
8
Uncertain significance and molecular insights of CPLANE1 variants in prenatal diagnosis of Joubert syndrome: a case report.
Li SX, Chen L, Deng C, et al.
BMC pregnancy and childbirth 2024; (24(1)):865 doi:10.1186/s12884-024-07052-3.
PMID: 39725884
9
Optimal prenatal genetic diagnostic approach for posterior fossa malformation: karyotyping, copy number variant testing, or whole-exome sequencing?
Juan Z, Cuixia G, Yuanjie C, et al.
European journal of medical research 2024; (29(1)):397 doi:10.1186/s40001-024-01993-3.
PMID: 39085968
10
Prenatal Diagnosis of Poretti-Boltshauser Syndrome - a Case Report of a Molar Tooth Sign Mimic.
Pereira-Macedo M, Grangeia A, Braga AC, et al.
Cerebellum (London, England) 2024; (23(6)):2646-2649 doi:10.1007/s12311-024-01728-4.
PMID: 39133430
11
Preventing transmission of dyschromatosis universalis hereditaria through preimplantation genetic testing: A case report.
Wang XL, Zou T, Wu YC, et al.
World journal of clinical cases 2025; (13(31)):110620 doi:10.12998/wjcc.v13.i31.110620.
PMID: 41283180
12
Combined Preimplantation Genetic Testing for Genetic Kidney Disease: Genetic Risk Identification, Assisted Reproductive Cycle, and Pregnancy Outcome Analysis.
Xiao M, Shi H, Rao J, et al.
Frontiers in medicine 2022; (9()):936578 doi:10.3389/fmed.2022.936578.
PMID: 35783601
13
IVF success rates in individuals accessing preimplantation genetic testing for monogenic conditions (PGT-M): a single centre retrospective cohort study of 572 IVF cycles.
Poulton A, Menezes M, Hardy T, et al.
Journal of assisted reproduction and genetics 2025; (42(5)):1567-1576 doi:10.1007/s10815-025-03416-6.
PMID: 40067642
14
Utilization of preimplantation genetic testing for monogenic disorders.
Lee I, Alur-Gupta S, Gallop R, Dokras A
Fertility and sterility 2020; (114(4)):854-860 doi:10.1016/j.fertnstert.2020.05.045.
PMID: 33040985
15
The number and rate of euploid blastocysts in women undergoing IVF/ICSI cycles are strongly dependent on ovarian reserve and female age.
La Marca A, Capuzzo M, Longo M, et al.
Human reproduction (Oxford, England) 2022; (37(10)):2392-2401 doi:10.1093/humrep/deac191.
PMID: 36006017
16
Case report and a brief review: Analysis and challenges of prenatal imaging phenotypes and genotypes in Joubert syndrome.
Huang LX, Lu XG, Liu JX, et al.
Frontiers in genetics 2022; (13()):1038274 doi:10.3389/fgene.2022.1038274.
PMID: 36468023
17
Prenatal diagnosis of Joubert syndrome: A case report.
Yen VTH
Radiology case reports 2024; (19(10)):4369-4374 doi:10.1016/j.radcr.2024.07.009.
PMID: 39165313
18
Non-classic splicing mutation in the CPLANE1 (C5orf42) gene cause Joubert syndrome in a fetus with severe craniocerebral dysplasia.
Zhu H, Chen W, Ren H, et al.
European journal of medical genetics 2021; (64(6)):104212 doi:10.1016/j.ejmg.2021.104212.
PMID: 33794348

This page explains the genetic recurrence risks of Joubert syndrome for educational purposes. Always consult a genetic counselor or maternal-fetal medicine specialist to discuss your family's specific risks and family planning options.

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