Tay Sachs Disease

Tay Sachs disease is a type of degenerating neurological disease caused by a deficiency of the enzyme protein hexosaminidase A. Because the enzyme is deficient, a lipid molecule called GM2 ganglioside builds up inside the lysosomes of cells. It's for this reason that doctors categorize it as a type of lysosomal storage disease.

The disease occurs when parents that are BOTH carriers of the genetic mutation have a baby. The most common carriers are Ashkenazi Jews, French Canadians and Louisiana Cajuns (1 in every 27), though carrier frequencies are also high in Irish Americans (1 in 50) and the general population (1 in 250). 

The disease typically occurs acutely in infancy, but there are three documented presentations: acute, subacute and late onset. 

The classic presentation, the acute (infantile) form, involves progressive motor weakness with loss of milestones and myoclonic jerking beginning at 3 months of age. 98% of patients develop seizures, and death typically occurs within the first few years of life. The severity is due a complete absence of the hexosaminidase A enzyme.

The subacute (juvenile) form will present as late as 9 years old, and is characterized by seizures, choreiform movements, speech problems and incontinence.  These children will typically develop dementia and won't live past the teenage years. 

Late onset Tay Sachs (LOTS, adult) cases have been reported in older patients, and usually involve subtle disturbances in speech, mood and psychological state. 

Pediatricians should suspect Tay Sachs Disease in any Jewish patient or patient of Jewish descent with delayed milestones and myoclonic jerks before the age of 1. Close inspection of the eye will typically reveal a cherry-red colored spot on the macula of the retina, which is only present in a few childhood diseases (Krabbe, Canavan, Alexander, and Gaucher diseases). A blood test will officially confirm the diagnosis. 

The differential diagnosis of neurologic progression in pediatric patients involves neurodegenerative disorders (spinal muscular atrophy/SMA, amyotrophic lateral sclerosis/ALS, Friedreich ataxia/FA and leukodystrophy)

Management of the disease involves maintaining nutrition, respiratory function and motor function while minimizing infectious diseases and seizures. Later forms benefit from both speech and physical therapies. All patients and their families should be referred to a certified genetic counselor for counseling. 

The prognosis for Tay Sachs disease is very poor. One retrospective study followed 97 infants diagnosed with Tay Sachs disease and noted that death occurs before the age of 5 in nearly all patients. Milestones such as head control, transferring objects from hand to hand and sitting without suport were acheived by the babies in over half the cases, but all lost their abilities by 1 year of age. The median lifespan of the infants was only 47 months.

Reference

Tay Sachs Disease. Dynamed Database. Updated May 12 2014. Accessed July 10, 2014. 

Your Child's Development: Pediatric Milestones

"Is my child developing normally?" 

This question is almost guaranteed during nearly all well child encounters in the pediatric office setting. Parents, rightfully so, are commonly concerned about their child's development and need a small amount of  reassurance from their professional caregiver. What are the guidelines that all pediatricians follow? 

The pediatrician references a set list of known guidelines when evaluating the development of a child. He or she often does this in three ways: using an Ages and Stages Questionnaire (sensitivity 75%, specificity 81%) filled out by the parent, asking the parent specific questions about the child and physically examining or interviewing the child. 

Below is the list of developmental milestones. It's important to remember two things:

1) The milestones are simply a guide: physicians use it to help determine if a child has fallen below normal when compared to other age-matched children. It is the job of the pediatrician to recognize a child that has fallen behind in one area and to offer support or resources to help him or her catch up (i.e, the Early Steps program).

2) All children develop differently. One child may meet all milestones on time while another may be persistently behind in one area. It's important to always be patient with (and supportive of) your child.

Pediatric milestones by age:

1 month

Vision: regards face, fixes transiently

Social: smiles spontaneously

6 weeks

Vision: follows to midline

Language: vocalizes (other than crying)

2 months

Hearing: alert to sound- localize by turning head and eyes

Social: cuddle when held, smiles responsively

10 weeks

Gross motor skills: lifts head prone 45-90 degrees

3 months

Language: coos (ooh, ah), laughs

Gross motor skills: head control when pulled to sitting position 

Fine motor skills: hands together

4 months

Vision: follows 180 degrees (visual tracking)

Language: squeals, makes raspberry sound, babbles d,t,z then b,m,p

Gross motor skills: may sit with support, raise head when lying prone

Fine motor skills: grasps rattle

5 months

Gross motor skills: rolls over (prone to supine)

6 months

Gross motor skills: pulls to sit without head lag, reach for toy, rolls both ways, sits with support and alone

Social: stretches arms to be picked up, shows likes

Warning sign: significant head lag, persistent fisting, persistent squint, persistent asymmetric tonic neck reflex, inability to roll over

8 months

Hearing: turns to voice

Gross motor skills: sits without support

Fine motor skills: transfers objects hand to hand, feeds self cracker

9 months

Hearing: turns directly to sound

Gross motor skills: crawls

Social: plays games, finger feeds, holds own bottle, object permanence

10 months

Gross motor skills: pulls to stand

Language: mama, dada, nonspecific, imitate speech sounds, repetitive consonants

1 year

Language: mama, dada specific one word other than mama and dada

Gross motor skills: pivots while sitting

Fine motor skills: bangs objects with hands, thumb/finger grasp, grasps by radial raking, "pincers" grasp, drops and throws toys

Social: indicates wants other than crying, comes when called

Warning sign: failure to sit without support, persistent squint

13 months

Gross motor skills: stands momentarily, cruises (stands and moves between large objects in room by hanging on)

14 months

Gross motor skills: walks well 

15 months

Language: immature jargonizing, understands "no", one-step commands, can point to body parts

Gross motor skills: climbs

18 months

Gross motor skills: kicks or throws ball

Fine motor skills: turns pages, feeds self with spoon

Social: follow simple commands, cuddles toys, enjoy imitative play, copies household tasks, plays some with others, symbolic play (thought)

Warning sign: inability to stand, no pincer grasp, no spontaneous vocalizations, abnormal hand posture

20 months

Language: 3 words other than mama/dada

2 years

Language: 50 words in vocabulary, "NO", can follow 2-part commands, points to named part of body, combines 2 words

Gross motor skills: run, walks up and down stairs with help, climb stairs alternating steps

Fine motor skills: spills little, uses cup, washes/dries hands, may help with dressing, eats by self, scribble spontaneously builds 6-cube tower, uses spoon, removes garment

Social: asks to go to toilet, plays with others (imitation), solitary parallel play (play side-by-side)

Warning sign: absence of recognizable words, lack of walking, tremor or ataxia

3 years

Language: gives first and last name, age, address, name parts of body, speech understandable to family, 3-4 word sentence, 250 word vocabulary, uses plurals, prepositions, pronouns

Gross motor skills: jumps in place, stand on 1 foot, kick ball, rides tricycle

Social: mostly toilet trained, participates in family life, plays interactive games (for example, tag)

Warning sign: speech not understood 75% of time

4 years

Gross motor skills: can heel walk, hops on 2 feet, climb ladder, tiptoe, hop, jump, balances on 1 foot for 5 seconds

Fine motor skills: dresses without supervision, copies, buttons clothes, uses pencil, glue, scissors, copies line and circle

Social: brush teeth, wash hands, toilet, separates easily from mother, enjoys jokes with parents, games with rules

5 years

Vision: recognizes 3 of 4 colors 

Language: counts 10 objects, names 4 colors; can define spoon and cat, can narrate story

Gross motor skills: skips

Fine motor skills: draws 6-part man (head, body, arms, legs), dresses/undresses without supervision, copy triangle, cut and paste

Social: understand good/bad, right/wrong

6 years 

Language: copies sound, composition of door/shoe/spoon

Gross motor skills: hop on 1 foot, walks backward heel-toe

• If you have any questions regarding your child's development, it's important to ask your pediatrician

• Research suggests that faster attainment of developmental milestones in first year of life associated with better educational outcomes at ages 16 and 31 years

• Studies have shown that bed-wetting at age 53 months is associated with a delay in developmental milestones 

• Speech should be intelligible by 3 years of age. If it isn't, the pediatrician will order a hearing evaluation

Reference

Developmental Milestones. Dynamed Database. Updated March 27, 2014. Accessed July 7, 2014.