Laboratory investigations usually show elevated creatine kinase, myopathic/dystrophic muscle pathology and altered α-dystroglycan. Antenatal diagnosis is possible in families with known mutations. Prenatal ultrasound may be helpful for diagnosis in families where the molecular defect is unknown.

Bloom syndrome is diagnosed using any of three tests - the presence of quadriradial (Qr, a four-armed chromatid interchange) in cultured blood lymphocytes, and/or the elevated levels of Sister chromatid exchange in cells of any type, and/or the mutation in the BLM gene. The US Food and Drug Administration (FDA) announced on February 19, 2015 that they have authorized marketing of a direct-to-consumer genetic test from 23andMe. The test is designed to identify healthy individuals who carry a gene that could cause Bloom Syndrome in their offspring.

There is no permanent cure for this syndrome, although patients can be treated according to their specific symptoms. The prognosis for those with Cockayne syndrome is poor, as death typically occurs by the age of 12. Treatment usually involves physical therapy and minor surgeries to the affected organs, like cataract removal. Also wearing high-factor sunscreen and protective clothing is recommended as patients with Cockayne syndrome are very sensitive to UV radiation. Optimal nutrition can also help. Genetic counseling for the parents is recommended, as the disorder has a 25% chance of being passed to any future children, and prenatal testing is also a possibility. Another important aspect is prevention of recurrence of CS in other sibling. Identification of gene defects involved makes it possible to offer genetic counseling and antenatal

diagnostic testing to the parents who already have one affected child.

Imaging studies reveal widespread absence of the myelin sheaths of the neurons in the white matter of the brain, and general atrophy of the cortex. Calcifications have also been found in the putamen, an area of the forebrain that regulates movements and aids in some forms of learning, along with in the cortex. Additionally, atrophy of the central area of the cerebellum found in patients with Cockayne syndrome could also result in the lack of muscle control, particularly involuntary, and poor posture typically seen.

Bloom syndrome has no specific treatment; however, avoiding sun exposure and using sunscreens can help prevent some of the cutaneous changes associated with photo-sensitivity. Efforts to minimize exposure to other known environmental mutagens are also advisable.

No specific treatment is available. Management is only supportive and preventive.

Those who are diagnosed with the disease often die within the first few months of life. Almost all children with the disease die by the age of three.

The most obvious, and often important part of treatment, is avoiding exposure to sunlight. This includes wearing protective clothing and using sunscreen (physical and chemical). Keratosis can also be treated using cryotherapy or fluorouracil. Theoretically, the condition could be completely corrected if functionally intact (non-mutated) endonuclease genes could be inserted into every cell into the body, and the most promising method to do this would be crispr. However, every cell in the body would have to be penetrated for a total cure, because the skin does not protect against other forms of radiation, like x-rays, even at low quantities harmless for those without xeroderma pigmentosa.

UV-sensitive syndrome is a cutaneous condition inherited in an autosomal recessive fashion, characterized by photosensitivity and solar lentigines. Recent research identified that mutations of the KIAA1530 (UVSSA) gene as cause for the development of UV-sensitive syndrome. Furthermore, this protein was identified as a new player in the Transcription-coupled repair (TC-NER).

Fewer than 40% of individuals with the disease survive beyond the age of 20. Some XP victims with less severe cases do manage to live well into their 40s.

Features of TTD can include photosensitivity, icthyosis, brittle hair and nails, intellectual impairment, decreased fertility and short stature. The acronyms PIBIDS, IBIDS, BIDS and PBIDS give the initials of the words involved. BIDS syndrome, also called Amish brittle hair brain syndrome and hair-brain syndrome, is an autosomal recessive inherited disease. It is nonphotosensitive. BIDS is characterized by brittle hair, intellectual impairment, decreased fertility, and short stature. There is a photosensitive syndrome, PBIDS.

BIDS is associated with the gene MPLKIP (TTDN1).

IBIDS syndrome, following the acronym from ichthyosis, brittle hair and nails, intellectual impairment and short stature, is the Tay syndrome or sulfur-deficient brittle hair syndrome, first described by Tay in 1971. (Chong Hai Tay was the Singaporean doctor who was the first doctor in South East Asia to have a disease named after him). Tay syndrome should not be confused with the Tay-Sachs disease. It is an autosomal recessive congenital disease. In some cases, it can be diagnosed prenatally. IBIDS syndrome is nonphotosensitive.

The photosensitive form is referred to as PIBIDS, and is associated with ERCC2 and ERCC3.

Knobloch syndrome is a rare genetic disorder presenting severe eyesight problems and often a defect in the skull. It was named after W.H. Knobloch, who first described the syndrome in 1971. A usual occurrence is a degeneration of the vitreous humour and the retina, two components of the eye. This breakdown often results in the separation of the retina (the light-sensitive tissue at the back of the eye) from the eye, called retinal detachment, which can be recurrent. Extreme myopia (near-sightedness) is a common feature. The limited evidence available from electroretinography suggests a cone-rod pattern of dysfunction is also a feature.

Knobloch syndrome is caused by mutations in an autosomal recessive inherited gene. These mutations have been found in the COL18A1 gene that instructs for the formation of a protein that builds collagen XVIII. This type of collagen is found in the basement membranes of various body tissues. Its deficiency in the eye is thought to be responsible for affecting normal eye development. There are two types of Knobloch syndrome and the case has been made for a third.

When caused by mutations in the COL18A1 gene it is called Knobloch syndrome type 1. The genes causing types II and III have yet to be identified.

Knobloch syndrome is also characterised by cataracts, dislocated lens with skull defects such as occipital encephalocele and occipital aplasia. Encephalocele is a neural tube defect where the skull has not completely closed and sac-like protrusions of the brain can push through the skull; (it can also result from other causes).

In Knobloch’s syndrome this is usually seen in the occipital region, and aplasia is the underdevelopment of tissue again in this reference in the occipital area.

Trichothiodystrophy (TTD) is an autosomal recessive inherited disorder characterised by brittle hair and intellectual impairment. The word breaks down into "tricho" – "hair", "thio" – "sulphur", and "dystrophy" – "wasting away" or literally "bad nourishment". TTD is associated with a range of symptoms connected with organs of the ectoderm and neuroectoderm. TTD may be subclassified into four syndromes: Approximately half of all patients with trichothiodystrophy have photosensitivity, which divides the classification into syndromes with or without photosensitivity; BIDS and PBIDS, and IBIDS and PIBIDS. Modern covering usage is TTD-P (photosensitive), and TTD.

Treatment is usually supportive treatment, that is, treatment to reduce any symptoms rather than to cure the condition.

- Enucleation of the odontogenic cysts can help, but new lesions, infections and jaw deformity are usually a result.

- The severity of the basal-cell carcinoma determines the prognosis for most patients. BCCs rarely cause gross disfigurement, disability or death .

- Genetic counseling

alterations in lipid and

carbohydrate metabolism, a triplet-repeat disorder

(myotonic dystrophy) and an idiopathic disorder

NBCCS has an incidence of 1 in 50,000 to 150,000 with higher incidence in Australia. One aspect of NBCCS is that basal-cell carcinomas will occur on areas of the body which are not generally exposed to sunlight, such as the palms and soles of the feet and lesions may develop at the base of palmar and plantar pits.

One of the prime features of NBCCS is development of multiple BCCs at an early age, often in the teen years. Each person who has this syndrome is affected to a different degree, some having many more characteristics of the condition than others.

Patients with Marfan-progeroid-lipodystrophy syndrome typically exhibit congenital lipodystrophy and a neonatal progeroid appearance. Sometimes identified as having neonatal progeroid syndrome, the term is a misnomer since they do not exhibit accelerated aging. The condition is caused by mutations near the 3'-terminus of the "FBN1" gene.

Audiometry (measuring ability to hear sounds of a particular pitch) is usually abnormal, but the findings are not particularly specific and an audiogram is not sufficient to diagnose Pendred syndrome. A thyroid goitre may be present in the first decade and is usual towards the end of the second decade. MRI scanning of the inner ear usually shows widened or large vestibular aqueducts with enlarged endolymphatic sacs and may show abnormalities of the cochleae that is known as Mondini dysplasia. Genetic testing to identify the pendrin gene usually establishes the diagnosis. If the condition is suspected, a "perchlorate discharge test" is sometimes performed. This test is highly sensitive, but may also be abnormal in other thyroid conditions. If a goitre is present, thyroid function tests are performed to identify mild cases of thyroid dysfunction even if they are not yet causing symptoms.

Fragile sites are associated with numerous disorders and diseases, both heritable and not. The FRAXA site is perhaps most famous for its role in Fragile X syndrome, but fragile sites are clinically implicated in many other important diseases, such as cancer.

Recently, chromatin bridges have been implied as a diagnostic marker for cancer, while having been linked to tumorigenesis in humans. This premise is based on the fact that as the mitotic cell divides and the daughter cells move further apart, stress on the DNA bridge leads to breakages in the chromosome at random points. As previously stated, the disruptions in the chromosome may lead to single chromosome mutations, including deletion, duplication and inversion, among others. This instability, defined as frequent changes in chromosomal structure and number, may be the basis of the development of cancer. While the frequency of chromatin bridges may be greater in tumor cells relative to normal cells, it may not be practical to utilize this phenomenon as a diagnostic tool. The process of staining and mounting sample cells using indirect immunofluorescence is time consuming. Even though DAPI staining is quick, neither laboratory technique can guarantee the presence of the bridges under the fluorescence microscope. The rarity of chromatin bridges, even in cancerous cells, makes this phenomenon difficult to be widely accepted diagnostic marker for cancer.

No specific treatment exists for Pendred syndrome. Speech and language support and hearing aids are important. Cochlear implants may be needed if the hearing loss drops to severe to profound levels and can improve language skills. If thyroid hormone levels are decreased, thyroid hormone supplements may be required. Patients are advised to take precautions against head injury.

A chromosomal fragile site is a specific heritable point on a chromosome that tends to form a gap or constriction and may tend to break when the cell is exposed to partial replication stress. Based on their frequency, fragile sites are classified as "common" or "rare". To date, more than 120 fragile sites have been identified in the human genome.

Common fragile sites are considered part of normal chromosome structure and are present in all (or nearly all) individuals in a population. Under normal conditions, most common fragile sites are not prone to spontaneous breaks. Common fragile sites are of interest in cancer studies because they are frequently affected in cancer and they can be found in healthy individuals. Sites FRA3B (harboring the "FHIT" gene) and FRA16D (harboring the "WWOX" gene) are two well known examples and have been a major focus of research.

Rare fragile sites are found in less than 5% of the population, and are often composed of two- or three-nucleotide repeats. They are often susceptible to spontaneous breakage during replication, frequently affecting neighboring genes. Clinically, the most important rare fragile site is FRAXA, which is associated with the fragile X syndrome, the most common cause of hereditary mental retardation.

Fitzpatrick et al. (2007) identified 41 children with CVS. The mean age of the sample was 6 years at the onset of the syndrome, 8 years at first diagnosis, and 13 years at follow-up. As many as 39% of the children had resolution of symptoms immediately or within weeks of the diagnosis. Vomiting had resolved at the time of follow-up in 61% of the sample. Many children, including those in the remitted group, continued to have somatic symptoms such as headaches (in 42%) and abdominal pain (in 37%).

Most children who have this disorder miss on average 24 school days a year. The frequency of episodes is higher for some people during times of excitement. Charitable organizations to support sufferers and their families and to promote knowledge of CVS exist in several countries.

Pterygium (conjunctiva) can be diagnosed without need for a specific exam, however corneal topography is a practical test (technique) as the condition worsens.

A careful history is of utmost importance when the diagnosis of pseudoporphyria is being considered. A personal and family history of hepatitis, porphyria, or photosensitivity disorder must be sought.

Although a genetic factor has not been considered in pseudoporphyria, one case of monozygotic twins developing pseudoporphyria after excessive UV-A exposure from long-term tanning bed use has been documented.

The patient should be thoroughly questioned regarding any symptoms of connective tissue disorder, which may be the underlying pathology of the photosensitivity. Recent reports suggest that a connective tissue disorder may be a predisposing factor in patients using nonsteroidal anti-inflammatory drugs (NSAIDs) who develop pseudoporphyria.

There is little hard evidence of death as a result of the condition. However, in severe cases the fluid loss can lead to potentially life-threatening electrolyte imbalances. The patient can also become malnourished if the attacks last too long without adequate replenishment of nutrients. With adequate medical interventions, most patients can be properly supported during an episode.