How the diagnosis is made
A chromosomal microarray (or genome/exome with CNV calling) finds it. A standard karyotype can miss it. Prenatal detection is increasingly common. Parental testing comes next.
The test that finds it is a chromosomal microarray (CMA/array-CGH) - a blood test that measures how much DNA you have from each part of the genome. A missing 1.4 Mb piece shows up clearly.
- A standard karyotype (looking at chromosomes under a microscope) usually cannot see a deletion
this small. This is a common reason for delayed diagnosis.
- FISH or MLPA can look specifically at this region if the lab knows what to look for.
- Exome/genome sequencing with copy-number calling also detects it, and is increasingly how people
are found.
- Prenatally, it can be found on cells from CVS/amniocentesis, and is now occasionally flagged by
some expanded NIPT/screening panels - which is why some families get a result before birth.
After a result, two questions follow:
- Which genes are actually in the deleted piece? Reports vary; the exact coordinates matter, and
they explain why two "17q12 deletions" can behave differently.
- Does a parent carry it? Testing both parents changes recurrence counselling and may trigger
useful screening for a parent who did not know.
A result is a lab report, not a prediction. A genetic counsellor can translate the coordinates into what they mean for your family.
Freshest finding: Introduction In South Korea, low‐resolution chromosomal microarray analysis (LR‐CMA) is frequently used as a screening tool to identify chromosomal anomalies in asymptomatic newborns.
Lab detail
- Interval typically reported (GRCh37): ~chr17:20.1-21.6 Mb; GRCh37/GRCh38 coordinates differ, and
breakpoint definitions vary between labs - a real source of confusion when comparing papers.
- Size ~1.3-1.5 Mb in most recurrent cases; atypical deletions extend beyond BP4 or stop before BP3
and can change the phenotype.
- CMA resolution comfortably covers 1.4 Mb; typical arrays detect deletions well below 100 kb.
- Parental testing by the same platform (or targeted FISH/MLPA/qPCR) is the standard follow-up.
Differential diagnosis the corpus keeps returning
- HNF1B point-mutation disease (no deletion, same gene) - clinically overlapping.
- Other recurrent CNVs with renal or neurodevelopmental features (e.g. 17q12 proximal/distal
deletions, 22q11.2, 16p12.1).
- Autosomal dominant polycystic kidney disease and other cystic kidney disorders.
- Other MODY subtypes (HNF1A, GCK, HNF4A) when diabetes dominates.
Reporting language to watch for
Reports and papers use "17q12 microdeletion", "17q12 deletion syndrome", "17q12 recurrent deletion", "HNF1B deletion", "RCAD" and "MODY5" for overlapping groups of people. Any literature search that only uses one term will miss a large part of the literature - which is why this project queries with all of them.
Latest evidence in the collected corpus
Clinical and Genetic Significance of Chromosomal Microarray Screening of Asymptomatic Newborns
Introduction In South Korea, low‐resolution chromosomal microarray analysis (LR‐CMA) is frequently used as a screening tool to identify chromosomal anomalies in asymptomatic newborns.
“M., "Novel Microdeletion Syndromes Detected by Chromosome Microarrays," Human Genetics 124, no.”corroboration 1 · confidence 97% · updated 2026-11-14 · source
Genetic evaluation and pregnancy outcome of fetuses with digestive system malformations: an eight-year single-center retrospective study.
2296-2360 14 2026 Frontiers in pediatrics Front Pediatr Genetic evaluation and pregnancy outcome of fetuses with digestive system malformations: an eight-year single-center retrospective study.
“Additionally, CMA identified 6 cases of likely pathogenic/pathogenic CNVs (pCNVs/lpCNVs) that were missed by karyotype analysis, including 17q12 microdeletion/microduplication, 16p11.2 microduplication, 22q11.21q11.22 microdeletion, 2q13 microdeletion, and…”corroboration 1 · confidence 97% · updated 2026-11-14 · source
Additional file 1 of Transient neonatal diabetes mellitus as an early diagnostic clue to HNF1B-related disease – two case reports and a literature review
Additional file 1 of Transient neonatal diabetes mellitus as an early diagnostic clue to HNF1B-related disease - two case reports and a literature review Supplementary Material 1: Supplementary Figure 1.
“The left bottom image shows a closer view of the deleted region of chromosome 17, marked with a black arrow, while the right bottom image shows the maximum deletion size (1.52 Mb), including the gene content.”corroboration 1 · confidence 97% · updated 2026-11-13 · source
The Prenatal Phenotype: Illustrating the Complexities of Genetic Testing and Interpretation With the Goal of Understanding the Fetal Presentation of Genetic Disease
The Prenatal Phenotype: Illustrating the Complexities of Genetic Testing and Interpretation With the Goal of Understanding the Fetal Presentation of Genetic Disease Advanced prenatal imaging and chromosomal microarray have improved detection of fetal anomalies, yet many structurally abnormal fetuses remain without a unifying diagnosis.
“The Prenatal Phenotype: Illustrating the Complexities of Genetic Testing and Interpretation With the Goal of Understanding the Fetal Presentation of Genetic Disease Advanced prenatal imaging and chromosomal microarray have improved detection of fetal…”corroboration 1 · confidence 97% · updated 2026-11-13 · source
Prenatal Ultrasound Spectrum of Fetuses with Chromosomal Copy Number Variations and Their Pregnancy Outcomes – a case series
Objective: To evaluate the prenatal phenotypic spectrum in correlation with chromosomal copy number variations and their pregnancy outcomes.
“Mean maternal age was 27 ± 7 years; 45.5% were primigravidae, and 45.5% had consanguineous marriages.”corroboration 1 · confidence 97% · updated 2026-11-13 · source
17q12 Microduplication Syndrome: The Need for Clinical Vigilance in Fetuses with Double Bubble Sign in the Era of Noninvasive Prenatal Testing
17q12 Microduplication Syndrome: The Need for Clinical Vigilance in Fetuses with Double Bubble Sign in the Era of Noninvasive Prenatal Testing Dear Editor, A 26-year-old woman, G2P1A0, underwent a normal nuchal translucency scan and received normal results from noninvasive prenatal testing (NIPT) for aneuploidy screening.
“Approximately one-third of individuals diagnosed prenatally with DUO have Down syndrome, and overall, 3%-5% of those with trisomy 21 present with DUO.[1] The double bubble sign typically manifests in late pregnancy; however, current prenatal care practices…”corroboration 1 · confidence 97% · updated 2026-11-13 · source
Genetic evaluation and pregnancy outcome of fetuses with digestive system malformations: an eight-year single-center retrospective study
Genetic evaluation and pregnancy outcome of fetuses with digestive system malformations: an eight-year single-center retrospective study Background Limited reports have investigated the genetic etiology of fetuses with digestive system malformations (DSMs).
“Additionally, CMA identified 6 cases of likely pathogenic/pathogenic CNVs (pCNVs/lpCNVs) that were missed by karyotype analysis, including 17q12 microdeletion/microduplication, 16p11.2 microduplication, 22q11.21q11.22 microdeletion, 2q13 microdeletion, and…”corroboration 1 · confidence 97% · updated 2026-11-13 · source
Retraction notice to “Prenatal diagnosis and molecular cytogenetic analyses of a rare 17q12 microdeletion and 17q11.2 microduplication family with normal phenotype” [Eur. J. Obstet
Retraction notice to "Prenatal diagnosis and molecular cytogenetic analyses of a rare 17q12 microdeletion and 17q11.2 microduplication family with normal phenotype" [Eur.
“Retraction notice to "Prenatal diagnosis and molecular cytogenetic analyses of a rare 17q12 microdeletion and 17q11.2 microduplication family with normal phenotype" [Eur.”corroboration 1 · confidence 97% · updated 2026-11-13 · source
This entry is version 3. The analytical engine only appends the clearly-labelled “Latest evidence” section; the text above is curated and is not rewritten by the machine. Confidence 85% · last updated 2026-11-14 16:44