Related Experiment Video

Updated: Aug 4, 2026

Chromosome Preparation From Cultured Cells
07:42

Chromosome Preparation From Cultured Cells

Published on: January 28, 2014

The syndrome of ring chromosome 12

N Scribanu, E B McCullars, R C Baumiller

    American Journal of Medical Genetics
    |January 1, 1980
    PubMed

    Insights

    A rare genetic condition, ring chromosome 12, was identified in a 13-month-old girl experiencing failure to thrive and developmental delay. This chromosomal abnormality (46,XX,r(12)(p13q24)) is linked to her significant growth and developmental issues.

    Area of Science:

    • Genetics
    • Pediatrics
    • Developmental Biology

    Background:

    • Failure to thrive (FTT) and global developmental delay are critical indicators of underlying genetic or metabolic disorders in infants.
    • Dysmorphic features can provide crucial clues for diagnosing rare genetic syndromes.

    Observation:

    • A 13-month-old female presented with severe FTT, delayed development, and distinctive physical characteristics.
    • Key dysmorphic features included epicanthal folds, low-set ears, a high-arched palate, short neck, clinodactyly, and a single palmar crease.

    Findings:

    • Karyotype analysis revealed a modal chromosome number of 46 with a ring chromosome 12 abnormality: 46,XX,r(12)(p13q24).
    • The patient's growth parameters were significantly below age norms, with weight-age at 1 month and length-age at 3 months.

    Implications:

    • Ring chromosome 12 is a rare chromosomal disorder associated with significant developmental and growth impairments.
    • Accurate genetic diagnosis, such as identifying r(12), is essential for appropriate clinical management and genetic counseling.

    More Related Videos

    Array Comparative Genomic Hybridization (Array CGH) for Detection of Genomic Copy Number Variants09:16

    Array Comparative Genomic Hybridization (Array CGH) for Detection of Genomic Copy Number Variants

    Published on: February 21, 2015

    Analysis of the Ambient Particulate Matter-induced Chromosomal Aberrations Using an In Vitro System08:48

    Analysis of the Ambient Particulate Matter-induced Chromosomal Aberrations Using an In Vitro System

    Published on: December 21, 2016

    Related Concept Videos

    Meiosis I01:49

    Meiosis I

    Meiosis is a carefully orchestrated set of cell divisions, the goal of which—in humans—is to produce haploid sperm or eggs, each containing half the number of chromosomes present in somatic cells elsewhere in the body. Meiosis I is the first such division, and involves several key steps, among them: condensation of replicated chromosomes in diploid cells; the pairing of homologous chromosomes and their exchange of information; and finally, the separation of homologous chromosomes by a...
    Karyotyping01:17

    Karyotyping

    Describing the number and physical features of chromosomes can reveal abnormalities that underlie genetic diseases. This description is facilitated by special staining techniques that produce a particular banding pattern on each chromosome. State-of-the-art techniques make this approach even more powerful, enabling the detection of individual genes that cause disease.A Simple Chromosome Staining Technique Provides Valuable Scientific InsightSome genetic diseases can be detected by looking at...
    Nondisjunction01:29

    Nondisjunction

    During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.
    Genomic Imprinting and Inheritance02:30

    Genomic Imprinting and Inheritance

    Diploid organisms inherit genetic material through chromosomes from both parents. Copies of the same gene are known as alleles. In most cases, both alleles are simultaneously expressed and allow various cellular processes to function optimally. If one of the alleles is missing or mutated, the expression of the other allele can compensate; however, this is not true for all genes.
    The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
    Meiosis I03:09

    Meiosis I

    Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of meiosis, where the genetic recombination of homologous chromosomes and the reduction of the ploidy level by half occurs.
    Prophase I is the most extended and complex step of meiosis I characterized by synapsis, chromosome pairing, and recombination of the homologous chromosomes. This process is facilitated by a proteinaceous structure called the...
    Nondisjunction01:21

    Nondisjunction

    Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers.  Nondisjunction is common during anaphase I or anaphase II of meiosis.  Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold sister...