Chromosomal disorders: what stands behind a genetic report

A chromosomal disorder is a change in the number or the structure of the chromosomes — the "volumes" in which genetic information is written. Some of these changes are well known and have names of their own; others are so rare that they have been described in a few dozen people worldwide. They have one thing in common: they explain the cause, but they do not describe the particular child.

What kinds there are

Type	What has happened	Examples
Trisomy	A chromosome is present in three copies instead of two.	Down syndrome (chromosome 21), Edwards syndrome (18), Patau syndrome (13).
Monosomy	One chromosome instead of a pair.	Turner syndrome in girls (a single X chromosome).
Sex chromosome abnormalities	An extra or missing X or Y.	Klinefelter syndrome in boys.
Deletion	A segment of a chromosome is lost.	Williams syndrome, cri-du-chat syndrome, 22q11 deletion.
Duplication	A segment is doubled.	Microduplication syndromes, some of them identified only recently.
Translocation	A segment has moved to another chromosome.	The translocation form of Down syndrome; a healthy parent may be the carrier.
Mosaicism	The change is present in only some of the body's cells.	Mosaic variants of the trisomies; the features are usually milder.

When it makes sense to see a geneticist

• developmental delay comes together with distinctive features of the face, hands or feet;
• there are malformations of internal organs, especially the heart and kidneys;
• height, weight or head circumference are noticeably outside the range for the age;
• the child has lost skills they had already acquired;
• there are seizures that cannot be explained by another cause;
• the family has already had children with developmental delay, repeated pregnancy losses, or a consanguineous marriage;
• a speech delay is combined with marked behavioural differences.

What it means for speech and development

In almost any chromosomal disorder speech turns out to be the vulnerable point, and usually for several reasons at once:

• reduced muscle tone — the tongue and lips work imprecisely, producing the picture of dysarthria;
• hearing problems — many syndromes come with anatomical features of the ear and frequent ear infections;
• weak auditory-verbal memory — long instructions are not retained;
• accompanying health problems — heart, endocrine system, vision; until these are under control, development is held back.

Hence the rule we start from: first remove what gets in the way physically, and only then increase the load in sessions. A child with undiagnosed hearing loss or untreated hypothyroidism will not show what they are capable of in any session.

How the work is built in our centers

1. The consultation. We assess speech understanding, oral praxis, attention and play — that is, the current state, not an entry in a summary.
2. Checking the obstacles. Hearing, neurological status, EEG where indicated, and the health checks specific to the main syndrome.
3. The program. Most often this is high-frequency therapy for the perception of speech, Z-Vibe for the articulatory muscles, micropolarization following an individual scheme, visual wave therapy where behaviour and sleep are disturbed, and SpeechLeader at the stage of working on pronunciation.
4. Review. The program is not written once and for all — it changes as the child changes.

What parents should keep in mind

• A diagnosis is a map, not a sentence. It says where difficulties are likely and what to check, but it does not set the limit of what the child can do.
• Descriptions on the internet are about the extreme cases. Scientific papers more often describe severe variants, because those are the ones that come to doctors' attention.
• The timing shifts, the order stays. A child goes through the same stages of development, only more slowly, and none of them can be skipped.
• Look for parent communities. With rare syndromes the experience of other families often turns out to be more practical than any set of recommendations.

Frequently asked questions

When does a child really need genetic testing?

When developmental delay comes together with at least one additional sign: distinctive facial or body features, malformations of organs, unusually short or tall stature, unusual behaviour, seizures, regression of skills — and also when the family has already had cases of developmental delay or pregnancy losses. An isolated speech delay in an otherwise healthy child usually does not require genetic testing.

Karyotype or microarray — which to choose?

A karyotype shows large rearrangements: an extra or missing chromosome, a translocation. A chromosomal microarray sees far smaller losses and duplications of segments that are invisible under a microscope, and so more often gives an answer in developmental delay without obvious outward features. Which test your child needs is decided by a geneticist after examining them.

The diagnosis has been made. What does that change?

Three things. First, it becomes clear what to monitor in terms of health: many syndromes have their own known set of risks — heart, hearing, vision, endocrine system. Second, a realistic planning horizon appears. Third, the family gets an answer about the likelihood of recurrence in a future pregnancy.

Does a genetic diagnosis affect the choice of sessions?

The choice, yes; whether there are sessions at all, no. We work not with the name of a syndrome but with what we can see in the child: whether they understand speech, what the tone of the articulatory muscles is like, how things stand with hearing and attention. The diagnosis suggests what to expect and what to check, but the program is determined by an in-person consultation.

Is the mosaic form easier?

As a rule yes: the smaller the proportion of altered cells, the milder the features. But the range is very wide, and it is impossible to predict from a percentage in a test how a particular child will develop.

See also

• Down syndrome: development and speech
• Child development milestones by age
• Early childhood autism: when a syndrome lies behind the behaviour
• Diagnosis G93.9: organic brain damage
• High-Frequency Therapy: how the course works

This material was prepared by the specialists of the Vlada Tarasenko Speech Restoration Centers. This material is for information only and does not replace an in-person consultation with a doctor or a speech pathologist. Only a doctor can make a diagnosis.