Development

Child development is often divided into different areas (gross and fine motor skills, language and cognition, as well as social-emotional development). 

Studies have established average ages at which specific developmental milestones will be reached. However, every child develops at their own pace. Slight deviations in one direction or the other are therefore completely normal. During check-ups with the pediatrician, the child’s development is monitored to determine whether it is within the normal range or whether individual areas require special support.

Both motor and cognitive development in children with PCH2 is severely impaired. Certain milestones, such as walking unaided or speaking in complete, grammatically correct sentences, are never achieved by children with PCH2. Nevertheless, children with PCH2 progress through developmental stages, albeit at very different rates from child to child, and the age at which they reach a developmental milestone is usually not comparable to that of healthy children.

Motor Development

Children’s motor development is divided into gross motor skills and fine motor skills. The following table provides an overview of important milestones in motor development in healthy children.

Motor Development Milestones in Healthy Children

Age	Fine Motor Skills Milestones	Gross Motor Skills Milestones
0 Months	Mmooth pursuit eye movement (SPEM)
1 Month		Lifts head in prone position
3 Months		Full head control in prone position; brings hands to mouth; props on forearms in prone position
5-6 Months	Palmar grasp	Sits with pelvic support; full head control when changing position
9 Months	Inferior pincer grasp	Sits steadily without support
10 Months		Creeps well in prone position; stands with hands held; pulls to stand
12 Months		Cruises around furniture; stands independently
14 Months	Superior pincer grasp
16 Months		Walks well and freely
2 Years		Walks up and down stairs, holding rail/without holding rail; runs well

Motor Development in Children With PCH2

Some children with PCH2 achieve the motor development milestones mentioned above (except for running), though usually with significant delays and limitations.

For example, the milestone of head control is achieved by more than half of the children, but not in the same way as in healthy children, where it remains reproducible and constant through changes in position. In many children with PCH2, however, brief periods of intentional head movement in a certain direction are clearly observed.

The milestone of rolling is also achieved by a large number of children with PCH2, and many children also showed attempts to grasp for objects offered to them. 

However, more complex skills are only achieved by very few children with PCH2. For example, sitting freely, creeping in prone position or purposeful grasping are only possible for a small number of children with PCH2. For example, purposeful grasping requires considerable effort, is often ataxic, and can only be sustained for a short period of time. Complex motor tasks, such as brushing one’s teeth, are generally not achievable.

Cognitive Development

Cognitive development encompasses the development of language and social behavior. However, skills such as SPEM can also be included in this category.

Cognitive Development Milestones in Healthy Children

Age	Language	Social Behavior/ Playing
1 Month	Throaty noises	Gazes at and follows objects
3 Months	Spontaneously vocalizes	Social smile
9 Months	Non-reduplicated babbling (different consonants, e.g. “ba-da-ga”)	Inspects objects visually and with hands/mouth
12 Months	Says first deliberate word; imitates language
18 Months	“Mom” and “dad” or analogous; uses 10-25 words	Hides and searches for toys; places toys in box
2 Years	Two-word sentences (noun + verb)	Imitates adult activities; simple roleplay
3 Years	Four-word sentences; uses pronouns correctly; uses plurals	Engages in roleplay and imaginative play; traces a circle
4 Years	Uses accurate grammar	Can name colors; can draw tadpole persons
5 Years	Accurate pronunciation	Plays games with rules and honors them

Cognitive Development in Children With PCH2

Similar to motor development, there are also significant differences in children with PCH2 when it comes to cognitive development.

While many PCH2 children respond to caregivers with recognition, show a social smile, fixate on and track high-contrast objects with their eyes, react to sounds, and communicate with vocalizations, only few reach the milestone of uttering specific words.

Developmental Constraints in PCH2 Children

In summary, what applies to the development of PCH2 children is the same as what applies to healthy children: every child is different, and it’s impossible to make an exact prediction. 

To use a metaphor: every child has a framework within which they can grow and develop. It may be slightly smaller for children with PCH. However, the extent to which a child with PCH will make use of this framework cannot be accurately predicted in advance. 

This depends on many factors: the severity of the symptoms, medication, stimulation and communication, and much more. 

Ultimately, however, it depends on that little person who, despite all the adversities that come with their condition, tries to make the best of it by developing, learning, experiencing, understanding, and communicating.

Scientific Background

Data From Literature

• Barth et al. described the severe impairment of motor and cognitive development in children with PCH2 as early as 1995. One of 16 children in his study reached the milestone of sitting freely, while 10 children were able to sit with trunk support. Six children did not reach the milestone of head control.
• Namavar et al. (2011) pointed out the severe impairment of voluntary motor skills in children with PCH2. One of 49 children in this study was able to sit independently, while 18 required support. Twenty-eight children did not achieve head control. Deliberate hand movements were observed in 10 of 55 children.
• In the study conducted by Steinlin et al. (2007), none of the 21 children examined were able to sit independently. One of the 21 children was able to vocalize words, and 8 of 21 children showed at least brief eye fixation and smooth pursuit eye movements.

Natural History Study from 2014

Skill	Number of Times Achieved	Median Age of Skill Acquisition in Months
Gross Motor Skills
Head control	23/33	12
Creeping in prone position	3/33	24
Rolling over	18/33	12
All-fours position	2/32	78
Sitting	3/33	48
Fine Motor Skills
Attempted grasping	25/33	12
Purposeful grasping	8/33	42
Language
Deliberate vocalizations	19/33	24
Uttering specific words	4/33	49,5
Adequate reaction to praise and rebuke	26/33	22
Social smile	24/33	11
Cognition/Communication
Recognition of caregivers	32/33	8
Reaction to familiar objects	29/33	22
Fixation on objects and SPEM	26/33	14,5
Reaction to sounds	28/32	18

Natural History Study from 2023

Skill	Number of Times Achieved (% and Absolute Amount)	Median Age of Skill Acquisition in Months
Gross Motor Skills
Head control	65 % (42/65)	9,5
Creeping in prone position	14 % (9/65)	18
Rolling over	48 % (31/65)	12
All-fours position	11 % (7/65)	19,5
Sitting	6 % (4/65)	32
Fine Motor Skills
Attempted grasping	69 % (45/65)	12
Purposeful grasping	35 % (23/65)	16,5
Language
Using specific sounds	48 % (31/65)	18
Uttering specific words	12 % (8/65)	30
Reaction to praise and rebuke	69 % (45/65)	19
Cognition/Communication
Social smile	85 % (55/65)	8
Recognition of caregivers	94 % (61/65)	6
Reaction to familiar objects	88 % (57/65)	12
Fixating	86 % (56/65)	10,5
SPEM	80 % (52/65)	12
Reaction to sounds	77 % (50/65)	12
Reaction to visual stimuli	94 % (49/52)	4,5

This entry was written to the best of our knowledge based on the reported experiences of parents of affected children. In addition, currently available data from the 2014 and 2023 Natural History Studies of PCH2 and from general medical literature has been included. It is not a substitute for consulting a medical professional. PCH2cure assumes no liability in this respect.